Human+Embryology+and+Development

toc = = =__**Human Embryology and Development/Female Reproductive System**__=

=**Female Reproductive System**=

**Functions and Roles of the Female Reproductive System**
The Female Reproductive __#|system__ is designed to carry out several functions within the female body. It produces the female egg cells that are necessary for reproduction. It also produces __gametes__, which are sex cells. These eggs/gametes are called the __ova__ or __ovum__. This system is designed to transport the ovum to the site of fertilization. The fertilization of an egg by a sperm is called __conception__. After conception, the uterus offers a __#|safe__ environment for a baby to develop before it is time for it to make its way into the outside world. However, if fertilization of the egg does not take place, the system is designed to menstruate. The __endometrium__ is the membrane that lines the uterus in preparation for pregnancy. However, if pregnancy does not occur, it is shed during menstruation. __Menstruation__ is the monthly shedding of the uterine lining. During __menopause__ however, the female reproductive system gradually stops making the female sex hormones necessary for the cycle to __#|work__. The female reproductive system produces __estrogen__ and __progesterone__ female sex hormones in which regulate the function of the ovaries.

The female reproductive system includes internal and external structures. The function of the genital area of the female is to enable sperm to __#|enter__ the body and to protect the internal organs from infectious organisms. The main external structures of the female reproductive system are the Labia Majora, Labia Minora and the Clitoris. The __Labia Majora__ encloses and protects the other external organs. It contains sweat and oil-secreting glands. The __Labia Minora__ surrounds the opening to the vagina and urethra. The __Clitoris__ is where two Labia Minora meet. It is very small and sensitive that is compared to a penis in males. Like the penis, the clitoris is very sensitive and can become erect. The internal reproductive organs include the Vagina, Uterus, Ovaries, Cervix, and Fallopian tubes. The __vagina__ is a canal that joins the cervix to the outside of the body. The __uterus__ is a hollow organ that holds the fetus. The main body of the uterus is called the corpus. The corpus can easily expand to hold the developing baby. The __ovaries__ are small, oval-shaped glands on either side of the uterus. They produce the eggs as well as estrogen and progesterone. The __cervix__ is a narrow neck like passage that forms at the lower end of the uterus. The __fallopian tubes__ are attached to the upper part of the uterus and are tunnels for the eggs. After conception, the fertilized egg then moves to the uterus where it implants itself to the uterine wall. **Did you Know?**  Conception occurs in the fallopian tubes  The egg and sperm meet within the fallopian tubes

= =

= = =** Pregnancy and Embryo Development to Implantation and Birth **=

** Process of Fertilization **
Fertilization occurs during sexual intercourse when the sperm from a male, travels through a woman’s vagina, through the cervix and into the uterus where it meets the matured egg. Millions of sperm cells are deposited into the vagina during sexual intercourse. However, only one is able to reach the egg and fertilize it. Once the sperm is inside the fallopian tube, the sperm attracts the egg by releasing a chemical. The egg is surrounded by a protective covering called the zona pellucida which only allows one sperm cell to penetrate it. Once inside the egg, the head of the sperm releases its genetic contents which fuse with the nucleus of the egg. Fertilization is now complete.

** Did you Know? **   Sperm are able to survive for 2-3 days within the female’s reproductive tract  The length of time for fertilization ranges from 12-24 hours

** Development of the Fertilized Egg **
After the process of fertilization, the egg then undergoes several divisions to form a structure known as a zygote. A __Zygote__ is a fertilized egg that is just starting to develop and is not yet an embryo. It then moves into the uterus within a 5-7 day period as it is then termed as an embryo. In the uterus, the embryo implants itself and burrows itself into the endometrium. After implantation of the embryo occurs, it secretes a hormone called Gonadotropin hormone. The __Gonadotropin hormone__ is a group of hormones secreted by the pituitary gland. These hormones stimulate the pregnancy. ** Did you Know? **   The gonadotropin hormone is used to detect the pregnancy through the blood/urine

** Implantation **
The fertilized egg, now known as an embryo develops in the fallopian tube for the first three days, and then it travels down into the uterus. By the fifth day it will become a blastocyst. A __blastocyst__ is a hollow ball of cells surrounding a cyst-like cavity. The blastocyst then hatches and is ready to adhere to the surface of the endometrium. It begins to secrete gonadotropin and progesterone hormones. = =

= = =**How Hormones Regulate and Control the Female Reproductive System**= = = __Hormones__ are chemical messengers that __#|enter__ the blood directly upon their secretion from the endocrine glands. A single gland/cell may secrete multiple hormones and many glands may secrete the same, single hormone. Hormones can also control ones’ emotions. It is especially noticeable right before a woman gets her period.

**Where do Hormones Come From?**
These chemicals are produced in the pituitary gland which is located in the brain. After they are produced, they travel through the blood stream into the ovaries. At this point, the ovaries are then given the message to start producing sex hormones.

**What is Estrogen and Progesterone and How do they Work?**
After the ovaries start to produce hormones, they begin to produce estrogen and progesterone. __Estrogen__ tells the immature eggs when to mature and it also helps the ovaries and other reproductive organs to grow. __Progesterone__ however only steps in during the last 10-14 days before a girl gets her period. It is what signals the uterus to create the uterine lining for the egg. **Did you Know?**  PMS is also known as Premenstrual Syndrome  It is common for a woman to get tired and moody right before their period  Cramps are caused when the ovaries are getting __#|ready__ to release an egg = = = =

= = =**Puberty in Females**= Puberty is a process that varies between girls. There is a wide range of ‘normal’ starting times, and it all depends on certain ethnic groups. For example, it may occur between 8-14 year old Caucasian girls while some African American girls reach puberty at 7 years of age. media type="youtube" key="ptCW_W07pzk" height="315" width="420"

**Symptoms**
Puberty consists of two major changes: Rapid height and weight increases and the development of breasts, pubic hair and underarm hair. The average age and stage of puberty variations are listed below:

**Stage one:** Childhood
 Ages: lasts through 8 to 11 years of age  What is occurring: There are no visible signs of development on the outside. On the inside however, the ovaries are beginning to produce hormones that will lead to development and enlargement of ovaries.

**Stage two:** Beginning of Puberty
 Ages: 11 to 14 years of age  What is occurring: Breast buds begin to show up. This raises the nipples and makes the areola slightly darker. Growth spurts are also common at this stage. Pubic hair begins to grow on the outer lips of the vagina.

**Stage three**
 Ages: 12 to 15  What is occurring: Breast growth continues as they become more round and full. Pubic hair becomes darker and coarser. Vaginal discharge also begins. This is when the vagina secretes a watery or mucous like fluid. The vagina also starts to get bigger, which means that most girls start their period at this time.

**Stage four**
 Ages: 12 to 16  What is occurring: The areola becomes darker and more sensitive. Armpit hair starts to appear. The pubic hair starts to form a triangular shape as it grows more in the front and on the sides of the genital area. At this time, it is highly likely to start ovulating and have a period. However, menstruation will be irregular for the next couple of years.

**Stage five:** adult stage
 Ages: 15 years to 19 years of age  What is occurring: Breast development is complete. Pubic hair is filled out as well as it covers the whole genital area. Growth spurt is complete and the woman has reached her adult height. Regular periods are occurring or, the woman might just be beginning to regulate. **Did you Know?**  The __Areola__ is a ring of pigmented skin that surrounds the nipple  Vaginal Discharge is either white, or clear in colour

=**Menstrual Cycle**=

**What Happens During the Menstrual Cycle?**
Females within the reproductive age (anywhere from 11-16 years) will experience cycles of hormonal activity that repeat every month. With every cycle, a woman’s body prepares itself for a potential pregnancy whether or not that is the woman’s intention. The average menstrual cycle takes about 28 days and occurs in the following phases:

**Follicular Phase:** This phase starts on the first day of the woman’s period.
 Events that occur: The follicle stimulating hormone (FSH) and Luteinizing hormone (LH) are released from the brain and travel through the blood stream to the ovaries. The __follicle stimulating hormone__ is a hormone that is produced by the pituitary gland. Its job is to stimulate the growth of follicles in the ovary. The __luteinizing hormone__ is also produced by the pituitary gland and it stimulates ovulation. These hormones stimulate the growth of about 15-20 eggs in the ovaries in its’ own “shell,” called a follicle. A __follicle__ is one of the small ovarian sacs that contain an immature ovum. As the follicular phase progresses, one follicle in one ovary becomes dominant and continues to mature. The remaining follicles stop growing and die. However, the dominant follicle continues to produce estrogen.

====**Ovulatory Phase:** This phase begins about 14 days after the follicular phase started. This phase is the midpoint of the menstrual cycle.====  Events that occur: The rise in estrogen from the dominant follicle triggers the brain on how much luteinizing hormone must be released. This causes the dominant follicle to release the egg from the ovary. __Ovulation__ is when the egg is released and captured by the fimbriae at the end of the fallopian tubes. __Fimbriae__ are finger-like projections at the end of the fallopian tubes that sweep the egg into the tubes. Also during this phase, there is an increase in the amount and thickness of mucous that is produced by the cervix. If a woman was to have sex in this phase, the thick mucous captures the man’s sperm and helps to move it towards the egg for fertilization. media type="youtube" key="nLmg4wSHdxQ" height="314" width="560"

**Luteal Phase:** This phase begins right after ovulation
 Events that occur: Once the egg is released, the empty follicle develops into a new structure called the corpus luteum. The __corpus luteum__ is endocrine tissue that forms in a ruptured follicle. This structure secretes estrogen and progesterone. Progesterone prepares the uterus for a fertilized egg to implant. If intercourse has taken place and the egg has been fertilized, it will travel through the fallopian tubes to implant in the uterus. However, if the egg is not fertilized, it passes through the uterus. The lining of the uterus breaks down and sheds, thus starting the menstrual period.

**How Many Eggs Does a Woman Have?**
During fetal life, there are about 6 to 7 million eggs. From this time, no new eggs are produced. At birth however, there are approximately 1 million eggs and by the time of puberty, only about 300,000 remain. Of these, 300 to 400 will be ovulated during a woman’s reproductive lifetime. The eggs continue to degenerate during pregnancy, with the use of birth control pills, and the presence or absence of regular menstrual cycles. **Did you Know?**  A woman is considered pregnant when the embryo implants itself in the uterus  A woman doesn’t necessarily have to have her period with certain birth controls  The vast majority of eggs steadily die until they are depleted at menopause

= =

= = =**Birth Control and How it Works**= There are numerous types of birth control that a woman can use to prevent pregnancy. Listed below are the different types of birth control, as well as their side effects and how they work:

 How it works: The most common type of birth control is a combination pill. These pills contain progesterone and estrogen that work together to prevent pregnancy. They prevent ovulation which means that a woman cannot get pregnant since there is no egg to be fertilized. The pill also thickens the mucous around the cervix which makes it harder for the sperm to reach the uterus. Most combination pills come in a 21-day pack or a 28-day pack. If a woman is using a 21-day pack, she will take the pill for 3 weeks, and then take a week off. During this week, the woman will have her period. However, if the woman is using the 28-day pack, she will take the pill every day. The 4th week pills contain no hormones so a woman will get her period at this time.  Things to be aware of: If the pill is forgotten, the woman’s chance of getting pregnant increases. The pill also does not protect against sexually transmitted diseases (STD’s).  How well it works: How effective the pill is, depends on if the woman remembers the pill every day. It also depends on if it is mixed with other medications. On average, 8% of couples a year who use the birth control pill will have an accidental pregnancy.  Side effects: The pill has very few side effects. Some that may occur are nausea, spotting, headaches, breast tenderness, and mood changes. However, some side effects such as lighter periods, reduced cramps and a less chance of ovarian cancer make life easier for many women.
 * 1) ==**Birth Control Pill**==

[[image:http://www.youngwomenshealth.org/images2/contraception_images/female_body_and_the_patch.gif width="412" height="322" align="right"]]**Birth Control Patch**
 How it works: The patch is very similar to the pill. They work in the same way to prevent pregnancy, except the patch is a thin, beige patch that sticks to the skin. Progesterone and estrogen are released through the patch and into the skin where the hormones work to prevent pregnancy. The recommended areas for the patch to be worn are on the abdomen, buttocks, upper arm or on the upper torso. Every week for three weeks, the patch is to be replaced with another one. On the forth week, the woman has her menstrual cycle.  Things to be aware of: The old patch must be removed before applying a new one. It is also very important for a woman to change her patch on the same day each week. To avoid skin irritation, the patch must be placed in a different area than the previous week. Also, the patch must not be placed onto any makeup, lotions or creams as it could effect how well the patch works.  How well it works: The patch is just as effective as the pill. However, if a woman is over 198 pounds, the patch may be less effective in preventing pregnancy.  Side effects: The side effects of using the patch are very similar to the pill. In addition however, the skin may get irritated where the patch was applied.

**Birth Control Ring**
 How it works: The birth control ring is a soft, flexible ring about 2 inches in diameter. It is directly inserted into the vagina where it releases progesterone and estrogen. This is very similar to the pill and the patch. A woman will insert it on the first day of her menstrual cycle and wear it for 3 weeks. On the same day it was inserted 3 weeks later, it is removed and within a few days, the woman should get her period. A week after the ring has been removed, a new one will be inserted.  Things to be aware of: The hormones do not take effect immediately so a woman should use another form of contraception during the first seven days of using the ring to prevent pregnancy.  How well it works: The ring is just as effective as the pill and the patch. However, if the woman does not use the ring correctly, it increases her chances of becoming pregnant. Also, any medications or health conditions a woman may have also effect how well the ring works.  Side effects: The side effects are very similar to both the pill and the patch. However, a woman may experience irritations or infections in the vagina as well as vaginal discharge.

[[image:http://www.popculturereviewed.com/wp-content/uploads/2011/05/depoprovera.jpg width="219" height="290" align="right"]]**Birth Control Shot**
 How it works: The birth control shot is a long-acting form of progesterone which is injected once every three months. The progesterone prevents ovulation from occurring, so a woman is unable to become pregnant. The shot is injected either in the upper arm, or in the buttocks.  Things to be aware of: Recent studies have linked bone density loss to the birth control shot. Therefore, woman who use the shot need to make sure that they are getting plenty of calcium every day. Also, women may notice a decrease in fertility for up to a year after the shot has been stopped.  How well it works: Less than 3% of couples who use the birth control shot will have an accidental pregnancy per year. However, the chance of becoming pregnant increases if the woman waits longer than three months before receiving her next shot.  Side effects: Women may have irregular or no menstrual cycle. They might also have weight gain, headaches and experience depression.



**Condoms**
 How it works: Condoms are a thin layer of rubber/latex that is worn on the penis. It keeps semen from entering the vagina. It is placed on the penis once it is erect. It must be unrolled all the way, to the base of the penis while holding the tip to leave some extra room at the end. That space is where the semen will go after the male ejaculates. It also ensures that the condom will be less likely to break.  Things to be aware of: Condoms cannot be reused. Therefore, a new condom must be used every time a couple has sex. The use of oil based lubricants is prohibited as they can break down the latex. Keep condoms stored in a cool, dry place.  How well it works: Over the course of a year, 15% of couples who use condoms properly will have an accidental pregnancy.  Side effects: Most couples have no problems when using condoms. However, an allergy to latex may occur. **Did you Know?**  The birth control pill can protect against some forms of breast disease  The birth control patch is still effective in water but just cannot be removed  The size of the patch cannot be altered in any way or it will not be effective  A week after the ring has been removed, a new one must be inserted even if the woman is still on her period.  The male must pull out of the vagina while the penis is still erect to prevent the condom from slipping off and allowing semen to enter the vagina

=**Diseases That Affect the Reproductive System**= __#|Diseases__ that affect the reproductive system can be uncomfortable and stressful. Some can even have long-lasting effects if not treated properly. Sexually transmitted diseases (STD’s) are the diseases that typically affect the reproductive system. The reproductive system is a group of organs that together, function to produce offspring. The complexity of the reproductive system, along with intimate contact makes the system vulnerable to a variety of diseases.

**Sexually Transmitted Diseases**
Sexually transmitted diseases (STD) are passed from person to person through sexual contact. There are over 25 different kinds of STD’s. Chlamydia is the most common STD. This may be due to the fact that chlamydia often goes undetected due to a lack of symptoms. Gonorrhea and Syphilis are also very common STD’s. STD’s can affect sex partners, fetuses and new born infants, thus meaning that it is inherited. Sexually transmitted diseases can be grouped into three categories:

**Category one:**
Sexually transmitted diseases that produce inflammation of the urethra, epididymis, cervix or oviducts. Chlamydia and Gonorrhea are the most common STD’s in this category. Chlamydia and gonorrhea can be treated and cured with either antibiotics or a diagnosis.

**Category two:**
Sexually transmitted diseases that produce sores on the external genitals are the most common diseases in this class. Diseases include syphilis, and genital herpes. Symptoms of herpes can be treated by antiviral drugs but the infection itself cannot be cured. Syphilis however is a bacterially caused infection and can, if left untreated, cause serious symptoms and even death in some cases. The disease syphilis is curable with antibiotics.

**Category three:**
This class of STD’s includes viral diseases that affect the organ systems other than those of the reproductive system. These diseases include Acquired immunodeficiency syndrome (AIDS) which is caused by Human immunodeficiency virus (HIV) and Hepatitis. These can be spread through sexual contact or through blood. Although there is no treatment for these diseases, they can be controlled with antibiotics. **Did you Know?**  Not all sexually transmitted diseases have noticeable or obvious symptoms  Sexually transmitted diseases can also be spread through anal sex

**Cancer**
Cancer is the abnormal and uncontrolled growth of cells. Cancer can occur in any cell within the human body. There are several types of cancer that affect the female reproductive system. Cervical cancer originates in the cervix, which is the organ that connects the uterus to the vagina. This cancer can originate from sexual activity in young teens. Another common cancer that affects the reproductive system is breast cancer. Breast cancer is a tumor that grows over time. This type of cancer can be inherited through families. Other risks are late first childbirth, late menopause, or even a high fat diet. Ovarian cancer is relatively rare, but most common cases are in women over 50 years of age. This type of cancer is usually undetected until it spreads within or beyond the pelvis. Uterine cancer is most common in postmenopausal women between 50 and 60 years of age. The main symptom is uterine bleeding. All types of cancer can be cured, with either removing the tumor, or radiation therapy. However, not everyone will survive because it depends how long the cancer has been spreading.

**Endometriosis**
Endometriosis is a disease that affects 10% to 15% of all women in ages 15 to 45. Endometriosis affects the lining of the uterus known as the endometrial tissue. The __endometrium__ is the membrane that lines the uterus in preparation for pregnancy. The exact cause of this disease is unknown but the immune system may contribute to the disease. Endometriosis causes the uterine lining to bleed at incorrect times during the menstrual cycle. It also can cause abdominal pain. Over time, endometriosis causes scar tissue to build up which can lead to infertility. There is no exact treatment for endometriosis, but it can be managed with any pain medications. Also, the process of endometriosis can be slowed down by the use of birth control.

**Pelvic Inflammatory Disease (PID)**
Pelvic inflammatory disease is an infection of the uterus, fallopian tubes and tissues in, and surrounding the ovaries. It is caused by sexual infections, such as gonorrhea. The infection occurs when bacteria travels from the cervix or uterus up through the reproductive organs. Symptoms many not appear at all, but when they do, they can include lower abdominal pain, pain during intercourse, irregular menstrual bleeding and pain during urination. Treatment consists of antibiotics, which cures the infection. However, if there was any damage to the reproductive system, there is no treatment for it.

**Trichomoniasis**
Trichomoniasis is a sexually transmitted infection that can affect both men and women. In women however, the symptoms may include a foul-smelling discharge, itching in the genitals and pain during urination. Treatment for Trichomoniasis consists of creams or gels inserted into the vagina or oral antibiotics.

=Vocabulary for Female Reproductive System=
 * Estrogen;** A hormone produced in a woman's ovaries that makes her develop typical female sexual structures and prepares her body for having a baby.
 * Progesterone;** A hormone produced to prepare the uterus for implantation of a fertilized egg, to maintain pregnancy and to develop the mammary glands.
 * Luteinizing Hormone (LH);** A hormone produced by the pituitary gland that stimulates ovulation.
 * Follicle Stimulating Hormone (FSH);** A hormone produced by the pituitary gland that stimulates the growth of follicles in the ovary.
 * Menopause;** When a woman's body no longer goes through the menstrual cycle so she is no longer capable of becoming pregnant.
 * Corpus Luteum;** Endocrine tissue that forms in a ruptured follicle following the release of an ovum.
 * Ovum;** An egg inside the female's body that is capable of being fertilized and becoming a baby.
 * Follicles;** One of the small ovarian sacs containing an immature ovum.
 * Menstruation;** The release of the uterine lining once a month when an ovum is not fertilized.
 * Endometrium;** The membrane that lines the uterus in preparation for pregnancy - if pregnancy does not occur, it is shed in menstruation.
 * Ovary;** One of the two organs in the female body that produce eggs and sex hormones (estrogen and progesterone).
 * Fallopian Tube;** The channel that connects the ovary to the uterus. The female body contains two, one for each ovary.
 * Uterus;** The organ in a woman's body where a baby develops.
 * Zygote;** A fertilized egg that is just starting to develop and is not yet an embryo.
 * Ovulation;** The release of an ovum from the ovary.
 * Vagina;** A woman's main sex organ, consisting of a tube that connects the outer sex organs to the womb.
 * Cervix;** The entrance to the womb.
 * Gametes:** sex cells
 * Conception**: Fertilization of the egg
 * Clitoris:** small sensitive area of the genitals
 * Labia Majora**: outer lips of the vagina
 * Labia Minora:** outer lips of the vagina
 * Hormones:** Chemical substances that carry messages through the blood stream
 * Gonadotropin Hormone**: hormone that is produced in the pituitary gland
 * Blastocyst:** hollow ball of cells in a cyst.

=Human Embryology and Development=

=Major Developmental Events from Implantation to Birth=

//Process of Fertilization//
Fertilization occurs during sexual intercourse when sperm travels through a woman's vagina, cervix and uterus to meet the mature egg in the fallopian tube. Although millions of sperm are released when a male ejaculates, it takes only a single sperm to penetrate the egg. Once fertilization takes place, the nuclei of the sperm and egg fuse to form a new cell called a __zygote__. The cell contains 46 chromosomes, 23 from each parent. As the zygote makes its way to the uterus, it divides - forming a __morula__ about 3 days after fertilization. The morula will soon develop a cavity and is now called a __blastula__. The cavity in this new cell formation will become the embryo. The blastula floats freely for about 2 days before attaching to the uterine wall and developing the placenta.

//Trimester One//
Early on before the woman realizes she is pregnant, her body is already working quickly to develop all of the embryo's main body systems - the circulatory system, neural tube, digestive tract and sensory organs are beginning to develop within the first four weeks (by week 10, all major organs will be fully functional). The embryo's head grows and develops quicker then the rest of the body early on in order to accommodate development of the brain. By week 6, the pituitary gland and muscle fibers are beginning to form and the embryo is capable of movement, although the mother can't feel them this early on in pregnancy. In week 8, the embryo resembles a human being - it now has eyelids, teeth (although not pushed through the gums), a rounded head and a nose. Already a week later the embryo has more distinct facial features. The placenta is being built up in the uterus to support the baby with plenty of essential nutrients needed for growth and development. The reproductive organs are also starting to develop by this week, although the sex of the fetus is still undetermined.

In the first four weeks of pregnancy, the woman may experience breast tenderness/fullness, bloating/cramping, beginning of food cravings and moodiness but no outward signs. She may still think of these symptoms as her normal menstrual cycle as many woman experience these similar feelings during that time. However, by week five the hCG hormones are high enough to be able to detect pregnancy through testing. Throughout early pregnancy, the expectant mother will experience a variety of symptoms. Some of these include extreme fatigue, a full bladder which happens because of increased blood flow to the pelvic area where the baby is located, and low blood sugar or blood pressure because of hormone surges. By week 10, hormones will work to slow down digestion so the body can obtain more nutrients for both the growing baby and mother. The mother may experience dizziness in the early weeks of pregnancy as well. This is due to progesterone increasing blood flow to the baby and decreasing blood flow to the mother's own body and brain.


 * //Interesting Facts://**
 * 80% of women will feel nauseous in the first trimester of pregnancy.
 * By week 7, the fetus is 10,000 times the size it was at conception.
 * Prenatal screenings are usually done between weeks 10 and 12.
 * By week 12, the risk of miscarriage drops dramatically.
 * The baby has a heartbeat of 150 bpm, which is twice as fast as an adult.

//Trimester Two//
By the beginning of the second trimester at week 13, the fetus is already 3 inches long! More sophisticated structures are forming, such as the vocal cords and the fetus may even have the coordination to suck it's thumb. It also has the coordination to swallow, wiggle it's tiny toes, squint and frown. As the fetus grows in length, the spine begins to straighten out more and not look as curved. The baby is covered in a downy coating called lanugo which will keep it warm until fat develops around week 17. By week 16, the baby can hear voices (which will be more sophisticated by week 23) and can perceive light. Nerves form connections to allow baby to differentiate senses at week 18. The urinary tract and circulatory system are functional and the baby's sex can be determined by week 20.

At the beginning of trimester two, the mother finally looks pregnant to the world! The uterus has taken up all space in the pelvis and now expands upward into the abdomen. She has to be extremely careful during this time period, as she is more susceptible to infections. This is because her immune system is repressed to decrease the chances of her body rejecting the fetus. However, chances of miscarriage are unlikely at this stage because the placenta is fully developed. This now sustains the baby's health and provides nutrients as needed. Colostrum (which carries nutrients, proteins and immune boosting antibodies) develop in the mother's breasts in preparation for breast feeding once the baby is born. Back pain is common during this trimester, since the abdomen muscles loosen to accommodate the growing baby, so the mother's back muscles have to overcompensate for balance.


 * //Interesting Facts://**
 * The placenta weights 1-2 pounds by birth.
 * Gum disease is linked to the health of the baby.
 * Mother may experience Braxton Hicks closer to her due date which are false contractions. They help to prepare for real labor and delivery!

//Trimester Three//
The baby now weighs one and a half pounds! It is possible for the baby to be born during the beginning of trimester three and still survive with special medical care. However, it is best for baby to be born at week 34 or later. It is a tight fit in the uterus and since the baby has coordinated movements, the mother will be able to feel them quite frequently. The baby's retina is developing in preparation for seeing the real world. However, it can only see about 8-12 inches away. At week 29, the baby's nutritional needs peak to need much more of vitamin C, protein, folic acid, iron and calcium to finish developing! In week 32 the baby's head moves downward to prepare for birth. Once the baby is around 18 or 20 inches long, it will no longer grow longer, only heavier. All the bones are hardened, except for the skull which will fuse after birth. At week 36, baby is now considered carried to term.

The expectant mother experiences similar symptoms to early pregnancy now that she has entered the third trimester. Her hormones have affected her vision, causing a decrease in tear production and sensitivity to light. Since her uterus has pushed up into her rib cage, she may often experience shortness of breath. Her uterus expands up to 1000 times its normal size to accommodate her baby.

//**Interesting Facts:**//
 * Gingivitis can lead to periodontal disease, which is linked to premature birth.
 * 20/20 vision isn't retained until age 7-9.
 * Nurses perform an Apgar score at one minute which baby normally scores around 7 on, and again at 5 minutes which should be at 9 or 10. This test evaluates baby's breathing, heart rate, reflexes, muscle tone and color.
 * Only 5% of babies are born on their due date.

//**Tips For Mother Throughout Pregnancy**//
 * Eat what looks/smells appealing and smaller, frequent meals to battle nausea. Also, avoid having an empty stomach, get out of bed slowly, drink between meals, get plenty of fresh air and avoid smoke, strong odors and caffeine.
 * Being well hydrated ensures your ability to breastfeed and keeps energy levels up.
 * Swimming is a great exercise choice!
 * Avoid heartburn by not lying down right after eating, eating slowly, avoiding fried or greasy foods, eating small meals and snacks.
 * Most women breast feed. It provides all the nutrients needed for the first 6 months of baby's life. It's easy to digest, protects against infections and disease. It also nurtures a relationship between mother and baby.
 * If a woman is in her 41st week, a doctor may suggest induced labor.

=Relationship of Diet between Mother and Fetus=

//What Is Best For Baby?//

 * 1) Fruits and veggies are a must! Include dark greens and bright colors every day
 * 2) Little or no added fat/sugar/salt
 * 3) Grains low in fat or whole grains!
 * 4) Low fat milk products, or fortified soy beverages if lactose intolerant
 * 5) Lean meats and alternatives (this includes dried peas, beans, tofu and lentils)
 * 6) Plenty of water

//What Foods Should I Avoid?//

 * 1) Raw fish
 * 2) Undercooked meat
 * 3) Food made with raw or lightly cooked eggs
 * 4) Unpasteurized milk products
 * 5) Raw sprouts
 * 6) __All alcoholic beverages__

It is very important for expectant mothers to make sure they are getting enough food to sustain both themselves and their growing baby. Studies have been done that show that women who have poor diets or are malnourished often give birth to babies that have physical disorders or neurological handicaps. It is estimated that around 24% of babies are born with less then average weights due to the mother not eating properly or enough.

It is most crucial in the first few weeks of pregnancy to be sure that the baby is getting enough vitamins, such as folic acid to ensure that it develops properly. Folic acid helps the neural tube develop properly so the baby isn't born with a condition such as Spina Bifida. Also, a diet rich in iron ensures the baby has enough oxygen flowing to it so they don't go into distress. Prenatal vitamins are a great idea for all women, even those who have a balanced diet. They need plenty to sustain both themselves and the growing baby.

Another important thing to be getting plenty of is __water!__ This is because most of the mother's weight gain is due to an increase in the amount of water in her body. The placenta is 85% water and the uterus is 70-90% water! Therefore, the mother must be sure to be well hydrated to make sure her body is continuing to function normally and that the baby develops normally as well.


 * //Did You Know?//**
 * 1) If a woman is pregnant with 2/3 babies, she will need to gain more weight. This is dependent on her BMI (body mass index)
 * 2) Folic acid is essential for the development of baby's spine, brain and skull in the first four weeks
 * 3) Take vitamin supplements three months before pregnancy and at least three months into to ensure baby gets all nutrients needed

=Ultrasounds and Amniocentesis=

//What Are Ultrasounds Used For?//

 * 1) Gathers information about the fetus
 * 2) Can determine due date, placement of the placenta, sex of the baby, perform health assessments, the number of babies, how well baby's heart works, size of the baby and to s[[image:http://www.pregnancycheck.com/img/pregnancy-ultrasound-17-weeks.jpeg width="217" height="167" align="left"]]ee if mother's fallopian tubes, uterus and ovaries are okay


 * 18-22 weeks is the standard time for an ultrasound to be done. May have an ultrasound at other times to see the position of the baby, check the placenta, the amount of fluid around the baby, baby's growth and well-being and to check for possible genetic problems

//How Does An Ultrasound Work?//

 * Creates an image of the inside of your body
 * Produces high pitched sound waves that travel through the body
 * Transducer picks up sound waves when they bounce back from organs
 * Clear gel is used on abdomen to allow the transducer to move easily and transmit sound waves into body


 * Does not use radiation, so it is safe for both mother and baby


 * //Interesting Facts about Ultrasounds//**
 * 1) May be asked to arrive with a full bladder (it helps sound waves travel better through skin and tissue)
 * 2) It can find some abnormalities with a fetus, but not all
 * 3) Clarity of picture depends on equipment used and how well it can pass through abdomen (thick or scarred skin produces an unclear image)
 * 4) Has been used for 30+ years, so it is considered safe and used strictly for medical purposes

media type="youtube" key="BO47arbpJTM" height="315" width="420"

//Amniocentesis//
Amniocentesis is a test done on the fetus while it is still in utero. Doctors take a small sample of the amniotic fluid surrounding your baby which contains genetic information about your baby. Doctors will first find an area of amniotic fluid that is far away from the baby and the placenta to be less intrusive. A long, thin needle is inserted through the stomach and into the uterus, extracting about two tablespoons worth of amniotic fluid to be tested. The purpose of the test is to specifically check for any chromosomal abnormalities. This test can only identify some chromosomal abnormalities, such as Down Syndrome. It won't be able to tell about other defects, such as a cleft lip.

Most women who will be offered having an amniocentesis done are women who had previous screening tests done that suggest their baby may have chromosome abnormalities, women with one or more relatives with a genetic disorder, or a previous pregnancy that had chromosomal abnormalities.

If you are considering having an amniocentesis done, it is best to talk to your doctor about it first as it does carry a risk of miscarriage (100 out of 600 women often have a miscarriage due to this test). This test is an intrusive one. It also carries the risk of your baby contracting hepatitis B or C, or even HIV if you have it. The test is usually not performed until the second trimester. This is because more amniotic fluid is surrounding the baby at this time, so the risk of miscarriage isn't as high even though it's still present.

=Labor and Delivery=

//Signs of Labor//
There are various things that your body does in order to prepare for the birth of a baby. Some of these include:
 * the baby dropping lower into your pelvis which is called __lightening__. This may occur as early as two to four weeks before actual delivery in first time mothers, or not until labor begins if a woman has previously experienced childbirth.
 * more easily able to breathe due to the baby dropping lower. This takes some of the pressure of your ribs and abdomen, including relief from heartburn, but may increase back pain.
 * increased vaginal discharge to prepare for the baby moving through the birth canal.
 * increased Braxton-Hicks, which are false contractions. These help prepare the uterus when the time comes to deliver the baby.
 * having a break in the amniotic sac.

//Chemicals Involved//
Oxytocin is the hormone that is released that begins contractions during labor and delivery. It also thins and dilates the cervix, moves the baby into the birth canal, releases the placenta (after-birth) and tells the body to release milk for breastfeeding. If a woman experiences low levels of oxytocin during labor and delivery, it can slow down or stop contractions (extending the length of labor) and cause excessive bleeding at the placenta site after birth.

Endorphins are released in a woman's body during labor and delivery in order to deal with pain. High endorphin levels may put a woman almost in another state to help her deal with the process of contractions and the pain of giving birth. This hormone gives you a sense of alertness after birth, allowing a woman to connect with her newborn.
 * Low drop of endorphin levels right after birth may contribute to the "baby blues" that some women feel early on after pregnancy.

Adrenaline is also involved in the process of labor and delivery. It is the "fight or flight" hormone that all humans experience. If a woman feels threatened during labor, she may produce high levels of adrenaline. However, too much adrenaline can cause in labor and delivery by: causing distress to the unborn baby, causing contractions to stop or slow down and creating a sense of panic (therefore increasing the amount of pain a woman feels).

//Pre-mature Labor//
Pre-mature labor is labor that occurs before the 37th week of pregnancy. A woman may be having pre-mature labor if she experiences the following symptoms:
 * a contraction every 10 minutes or more than five within one hour
 * menstrual-like cramps
 * low, dull backache
 * pelvic pressure that may feel like the baby is pushing down

Also, there are some possible risk factors that are associated with a higher chance of having pre-mature labor. However, if a woman experiences any of these, it does not necessarily mean she will have pre-mature labor:
 * pre-mature labor or delivery during a previous pregnancy
 * misshapen uterus
 * abdominal surgery during pregnancy
 * carrying more than one baby (twins or triplets are often known to be born early)
 * excessive amount of amniotic fluid
 * using recreational drugs
 * extreme emotional or physical stress

//Labor Contractions//
When a baby is ready to be born, the body will release a hormone called oxytocin that begins the uterine tightening. The upper portion of the uterus will tighten while the lower portion will relax to allow the baby to move from the uterus into the birth canal. These are contractions and occur regularly. In early labor, some women describe them as similar to menstrual cramps. They have a wave-like sensation to them, starting in your back and working around to the front. They start off lower in intensity, build up to the peak and gradually subside. Once your body is close to actually delivering the baby, the peak of each contraction will last longer and the contractions will be closer together.

//Pushing During Labor//
Once the cervix is fully dilated and a smooth passageway is made, you will be able to begin pushing. This period of delivery varies in length but can usually last up to one or two hours for first time mothers. During this stage, contractions occur about every five minutes and can last anywhere from 45 to 90 seconds. Along with these contractions may be an urge to push. You are now working with your contractions to push your baby out into the world. However, if a woman has received an epidural, she may be numbed and not able to fully feel the urge to push along with the contractions so this process may be more difficult.

//Induced Labor//
A doctor or midwife may suggest a woman have induced labor if a woman is more than one week overdue or if she has a medical condition such as diabetes or high blood pressure. Labor can be induced by a physician breaking a woman's bag of water or by intravenous administration of __pitocin__. Pitocin is a synthetic form of oxytocin which is the the natural hormone that stimulates labor. When a woman is administered this drug, the baby needs to be carefully monitored. Pitocin is increased in dosage slowly so no harm is done to either mother or baby and to also mimic spontaneous labor. However, contractions may feel more intense, peak sooner and cause labor to be shorter.

//Post Delivery//
Once a baby is delivered, it is important that they are dried off and kept warm as they are unable to regulate their own temperature. This is best accomplished through wrapping them in a blanket or skin to skin contact with the mother. The umbilical cord will be clamped and cut either immediately after birth or a few minutes afterward. Blood is collected from the umbilical cord to test the baby's blood type and perform other tests that may be necessary. When a baby is born, they will have fluid in their mouth and nose which needs to be suctioned out so they are able to breathe properly. This is usually done once the baby's shoulders are delivered or shortly after the baby is fully delivered. Once the baby is settled, an Apgar assessment will be done. This assessment evaluates the baby's heart rate, breathing, muscle tone, reflex response and color. Within five minutes after birth, a baby should typically score about a 7. Ten minutes after birth, most babies will score either a 9 or 10.

An ID bracelet will be put on the baby, the mother and the partner before the baby is removed from the room for any reason. Once the baby's temperature is stable, the nurse will give them a sponge bath and have a pediatric exam performed on them. Many of these procedures are done in the nursery but can be done in the mother's room if they prefer it. Also, if a mother is breastfeeding, it makes more sense to have the baby stay in the room with the mother. Pre-natal screening tests should be performed on all newborns within the first few days and no later than a week old. Some diseases may not come up on tests until a few days after birth and it's important to be aware of your baby's health conditions.

=Birthing Options= There are numerous options when it comes to childbirth. Each woman may have different wishes when it comes to delivering her own baby and with updated technology, there are a variety of choices she can pick from. Some of these include:
 * Delivering her baby at home vs. delivering at the hospital
 * Having a vaginal birth
 * Having a water birth
 * Having a cesarean section (also known as a C-section)

//Vaginal Birth//
This option is the most common method of childbirth. Women who give birth this way are able to go home earlier and avoid risks involved with major surgery, such as having a C-section. There are a variety of medications available to take for pain, such as epidurals, but it is not required to use when delivering in this way.

//Water Birth//
This option is not as common as vaginal birth, however it does provide more comfort for the mother and an easier birth. Once a woman is in labor, she will be entered into a tub of water and the baby's condition will be monitored using a special Doppler device. The water allows the mother to move freely and helps reduce the amount of pain she may experience. It also relaxes her muscles and helps to reduce any anxiety she feels. Once it is time to deliver, the woman can choose to either deliver inside the tub or above the surface.

//Cesarean Section//
This option is used if an emergency occurs while a mother is delivering or if a woman has risks of complications, birth defects or is having multiple babies. The doctor will make an incision in the abdomen and uterus to remove the baby. This option has a longer recovery period then other childbirth methods.

//Hospital Birth//
Delivering in a hospital is the best method if you want the most up-to-date medical technology. There is easy access to well trained staff and machines that can be used in case of an emergency. If something goes wrong, everything you need to ensure your baby is delivered safe and healthy is on hand so a woman can breathe easily knowing she is in good hands.

//Home Birth//
If a woman decides to deliver her baby at home, it is recommended that her pregnancy has been trouble free and she is not expected to have any complications with delivery so the birth is safe for both herself and her baby. Having a birth at home offers the comfort of being in a familiar atmosphere. The woman is more involved with the decisions that take place during labor and delivery as well. However, if she chooses this option, she must plan in advance. She will need to speak to her doctor to make sure facilities will be provided. Also, if an emergency arises and the woman is unable to have a vaginal birth, she will need to be transferred to the closest hospital to have better medical attention so the baby is delivered safely.

=Distress in Mother or Baby During Delivery=

//Distress in Baby During Pregnancy//
There are a few warning signs an expectant mother should be aware of, especially if she carries a risk of her baby being in distress. One of these signs is leaking of amniotic fluid. If a woman feels she has peed her pants or that she can't stop urinating, there may be a leak in the amniotic sac. This is important to determine if it's actually happening as it can lead to pre-term labor. The amniotic fluid is what surrounds the fetus while it is developing and protects it from harm that may arise. If a woman suspects an amniotic leak, she needs to go see her doctor as soon as possible to be tested to see if that is the problem. Another important sign to pay attention to is any vaginal bleeding. This may signal oncoming labor or a tear in the placenta, both which need to be dealt with immediately. However, if the bleeding is light pink and just spotting, it may be due to intercourse or over activity, both which is normal. Finally, any signs of pre-mature labor should be dealt with immediately as well.

There are some signs that the baby itself is in distress. This usually means that the baby's oxygen supply is being depleted in some way or another. This could be due to maternal illness, placental abruption, umbilical cord compression, fetal infection or because the mother is in a position that puts pressure on major blood vessels, cutting off the oxygen flow to the fetus. The risk of this is higher in women who have a multiple pregnancy (twins or triplets). An expectant mother can try to determine if her baby is in distress if the baby's heartbeat is lower than normal, they change the pattern of their movements (or stop moving entirely at times) or pass their first stool while in utero (called meconium). If a woman suspects her baby is in distress, she should call her doctor and get checked out right away. It's better to confirm that things are okay then to push aside worries or concerns she may have.

//Distress in Baby During Delivery//
When distress happens during labor and delivery, different actions will be taken depending on how far along the mother is and what risks are involved. For example, if a baby's oxygen supply becomes compromised during labor, a doctor may quickly decide if an emergency C-section is what's best for mother and baby. Usually a C-section is a common way to respond to fetal distress, but it is not always the best option. Each situation is unique and will be handled differently depending on what the doctor and mother decide is the best route to take.

=Chromosome Abnormalities, Miscarriages and More=

//Fetal// //Alcohol Spectrum Disorder (FASD)//
There is no safe time or amount to drink alcohol during pregnancy! If a woman drinks while pregnant, this could lead to a baby born with FASD. __This disease is not curable__. Children with this disability have problems with learning and behavior, thinking things through, and tend to be socially awkward. Alcohol rapidly reaches the baby through the mother's bloodstream.

//Smokin////g and Pregnancy//
If a woman is pregnant, it is best for both her health and especially the health of the baby to __not__ smoke while pregnant. Smoking increases the chance of having a miscarriage, having complications in labor and delivery, along with lowering the baby's birth weight. The baby will get the same chemicals as the mother, many of which are extremely toxic and related to cancer. Smoking while pregnant decreases the amount of oxygen and nutrients the baby receives. It also can cause problems later in life for the baby, including an increased chance of having asthma and a weakened immune system.

//Miscarriages//
Miscarriages occur more often then people may realize. 1 in 5 pregnancies usually end in a miscarriage. Miscarriages can be a sign that something is wrong with the fetus, such as a chromosomal condition like Down Syndrome or Turner's Syndrome. 60% of miscarriages that occur are usually because of the chromosomes of the egg and sperm not combining properly at conception. They can also occur due to to abnormalities with a woman's reproductive organs, infections she may contract or other environmental influences. If there is possibility that a miscarriage happened due to infection or abnormalities, testing can be done to try to pinpoint the cause and try to decrease the risk of miscarriage happening in future pregnancies.


 * To try to reduce the risk of having a miscarriage, a woman should have immunizations updated, dental work done and any medical problems looked after. She should also be eating healthy and taking in folic acid to help the baby's development of it's neural tube. In addition, she should reduce how much alcohol she drinks and quit smoking. She could look into her family background of any genetic defects as well.

//Down Syndrome//
Down syndrome is a condition in which a person has an extra copy of Chromosome 21. This usually takes place during the formation of reproductive cells. An error in cell division called nondisjunction causes one of the reproductive cells to have an abnormal number of chromosomes. If that particular cell contributes to the genetic makeup of a child, that child will have Down Syndrome. This extra chromosome affects a person's brain development and in the development of the rest of their body.

Some physical signs of Down Syndrome include:
 * A flat face with an upward slant to their eyes
 * Poor muscle tone
 * Small hands and feet
 * White spots in the iris of the eye

People born with Down Syndrome are more likely to have certain health conditions. Some of these include:
 * Heart disease
 * Hearing problems
 * Celiac disease
 * Skeletal problems
 * Dementia

Down Syndrome is not a disease that can be cured. However, it is possible for people born with this disease to live full functional lives. Many people with Down Syndrome benefit from having speech therapy, occupational therapy and exercises to help improve motor skills.

The risk of having a baby born with Down Syndrome increases with a woman's age. Women aged 25 have a 1 in 1,250 chance of having a baby born with Down Syndrome while women aged 40 and older have a 1 in 100 chance.

//Turner's Syndrome//
Turner's Syndrome is a chromosomal condition that affects development in females, since it is related to the X chromosomes and females have XX chromosomes. A normal woman will have two X chromosomes in each cell, but women with Turner's Syndrome only have one or may have the second one structurally altered. Many women who have this condition experience an early loss of ovarian functions and many of their eggs die prematurely, causing them to be unable to conceive. Affected women will not undergo puberty unless they receive hormone therapy. Some other signs of the condition include a webbed neck, puffiness or swelling of the hands or feet, skeletal abnormalities and kidney problems. Many people born with this also have heart defects, such as a narrowing of the large artery (coarctation of the aorta) which can be fatal. Most people that have this disease usually never actually are carried to term, since most cases happen with miscarriages or stillbirths.

//Spina Bifida//
Spina Bifida is a condition in which a baby is born with an opening in the spine. Most spines are completely closed to protect the spinal cord which is a group of nerves that send messages from your brain to the rest of your body. However, babies born with this condition did not develop properly in the mother's womb. An opening is left in the spine and it may protrude from the rest of the body. Since the spine is open, some nerves may be damaged. The brain might not be able to properly send messages to the rest of the body and the person may experience some paralysis. The amount of paralysis depends on where the opening is in a person's spine. If it is lower down, it may be minimal compared to if it was higher up. People with this condition may use the help of crutches, leg braces or wheel chairs in order to get around.

Doctors aren't 100% sure why this condition happens, but they think it is related to the amount of folic acid in a pregnant woman's diet. Folic acid is found in foods such as broccoli, spinach, egg yolks and oranges. If a woman doesn't have enough folic acid in her diet, she has an increased chance of having a baby born with Spina Bifida. However, women are able to take supplements of folic acid throughout pregnancy to ensure that their baby has enough to develop normally.

//Depression//
About 1/10 women experience depression during pregnancy. Signs of depression can include: inability to concentrate, anxiety, extreme irritability, frequent mood swings, sleep problems, extreme fatigue, persistent sadness and a dramatic change in appetite, either increased or decreased. However, by sleeping lots, eating regularly, exercising and avoiding stress will help a woman keep her moods and other symptoms in check!

//Cat Litter//
If a woman is expecting, she should leave litter duty to her husband. This is because she could contract oxaplasmosis which is a rare infection from a parasite in cat feces or raw meet. The effects are serious for the unborn baby, including birth defects such as seizures, liver problems and blindness.

=Vocabulary 2=

**Morula;** The mass of cells resulting from the cleavage of the ovum before the formation of a blastula. **Blastula;** The early developmental stage of an embryo, following the morula stage and consisting of a single, spherical layer of cells enclosing a hollow, central cavity. **Gastrula;** A metazoan embryo in an early stage of germ layer formation following the blastula stage, consisting of a cup like body of two layers of cells, the ectoderm and endoderm, enclosing a central cavity, or archenteron, that opens to the outside by the blastopore: in most animals progressing to the formation of a third cell layer, the mesoderm. **Neurula;** An embryo in the stage of development in which part of the ectoderm is differentiated into neural tissue and in which the neural tube, which develops into the brain and spinal cord, is formed. **Chorion;** the outermost of the extra embryonic membrane so land vertebrates, contributing to the formation of the placenta in the placental mammals **Amniotic Sac;** A two-layered membrane that surrounds the embryo or fetus in the uterus. The sac is filled with fluid in which the embryo or fetus is suspended. **Umbilical Cord;** a  cord or funicle connecting the embryo or fetus with the placenta of the mother and transporting nourishment from the mother and wastes from the fetus.
 * Fetus;** A developing baby before it is born.
 * Placenta;** The organ in which a baby is connected to it's mother's blood supply in her womb before birth.
 * Colostrum;** carries nutrients, proteins and immune boosting antibodies. Develops in the mother's breasts.
 * Oxytocin;** Hormone secreted by the pituitary gland that stimulates contractions and the ejection of milk.
 * Caesarean Section;** The delivery of a fetus through a surgical incision through the abdominal wall and uterus.
 * Fertilization:** process in sexual reproduction whereby the egg and sperm unite
 * Invitro Fertilization:** eggs are fertilized in petri dish, then implanted in the uterus
 * Trisomy:** presence of three homologous chromosomes in every cell (*Homologous - having the same genes or alleles in the same order of arrangement).
 * Monosomy:** presence of one chromosome in place of a homologous pair
 * Down Syndrome:** trisomic disorder which zygote receives three chromosomes for #21
 * Turner's Syndrome:** produces a female with one one X chromosome. //In egg cell, both X chromosomes move to same pole during meiosis I. Once egg is fertilized, a zygote with 45 chromosomes is produced. They usually don't develop sexually. Most fetuses with this mutation are miscarried before the 20th week.//

//References//
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www.youtube.com

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[|http://www.livestrong.com/article/12459-puberty-stages-development-females/#ixzz1r8X5A8AN]

http://kidshealth.org/teen/sexual_health/contraception/contraception.html

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[|http://www.canadianparents.com/article/weekbyweek-pregnancy-guide-weeks-14]

[|http://www.canadianparents.com/pregnancy/week-by-week-guide?gclid=CLnbmoacnK4CFaYAQAodACIibw]

[|http://pregnancy.about.com/od/fetus/a/uswbw.htm]

[|http://www.sogc.org/health/pregnancy-ultrasound_e.asp]

[|http://www.phac-aspc.gc.ca/hp-gs/pdf/hpguide-eng.pdf]

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