1. Trimester One Corbyn, Whitney, Ashley, Brittany

2. Week One & Two -not actually pregnant the first week or two - sperm and egg unite in one of your fallopian tubes to form a zygote -zygote has 46 chromosomes - 23 from oocyte and 23 from sperm -amnion sac is formed Week 3 -Nervous system begins to develop -heart beating starts -At this point the baby is smaller then a pen point

3. Week Two

4. Week Three  -Nervous system begins to develop -heart beating starts -At this point the baby is smaller then a pen point

5. Week Four  Although you are as yet unaware that you are pregnant, your baby is already undergoing great changes.  The fertilized egg is now a quickly growing ball of cells called a blastocyst.  It is embedded more deeply in the uterine wall and the amniotic cavity is being formed.  The group of cells that will make up the placenta is being organized and circulatory networks containing maternal blood are being formed. Three layers of cells are sorting themselves out within the blastocyst. The ectoderm will form the nervous system, hair and skin of your baby. The endoderm will become the lining of the gastrointestinal tract, and various organs like the thyroid, liver and pancreas. The mesoderm will develop into the skeleton, connective tissues, blood systems, urogenital system and most of the muscles

6. Week Five Your baby is now an embryo (so- called due to the little tail at the end of its developing spine) and is only barely visible to the naked eye. The spinal column, brain and heart have begun to develop. Baby is about 1/16th of an inch long

7. Week Six  The baby's heart has begun to beat! At about ½ inch long your little one is the size of your little fingernail.  He has begun to grow buds where his arms and legs will be and his head has the beginnings of eyes, ears and a mouth. Starting prenatal care now is essential. For the next four weeks your baby will be most vulnerable to factors that can interfere with proper development.  Now is the time, if you haven't already, to stop smoking, drinking or indulging in recreational drugs. Also, be particularly sensitive to environmental risks such as exposure to chemicals, tobacco smoke and animal diseases; some of which, toxoplasmosis for instance, can be contracted by humans

8. Week Seven  The baby's heart is now beating regularly at 150 beats per minute.  The arm buds have grown and now the hands are beginning to develop.  The whole baby is still only 1/3 of an inch long, but the brain, intestines, pituitary gland and pancreas are growing.  Though the genital tubercle is present, you can't tell by looking whether it is a girl or a boy, yet.  The baby's face is developing rapidly, the nasal pits have formed, the ears are developing and there are developing lenses on the eyes.

9. Week Eight  Your baby is now about 10,000 times bigger that it was at conception but is still only about an inch long.  This week the baby's gonads will either become testes or ovaries. The eyes are formed and covered by a fold of skin, though the eyelid will not open yet.  The arms and legs are growing longer and the arms are bent at the elbow, allowing the baby to hug herself. The tip of the nose is now visible and teeth are forming under the baby's gums.  Your little one is beginning to move around now and kick his legs, but he is still way too small for you to feel it.

10. Week Nine  The baby officially changes from being an embryo to a fetus this week. This is mostly due to the fact that his little embryonic tail has disappeared.  Bones and cartilage are beginning to form.  The umbilical cord and placenta are forming and growing.  If touched from the outside of the uterus, the baby will respond by moving. The fingers have formed but are webbed. Fact: at the end of this week the babies arms are the length of this printed 1

11. Week Ten Most of the baby's joints are formed now-shoulders, elbows, wrist, hands and fingers, knees, ankles, feet and toes. All of his organs are present and accounted for, but not fully formed or functional. Your little one is now about as long as a paper clip and weighs the same as four paperclips, in other words: 1 ¾ inch and ¼ oz.

12. Week Eleven  Your baby's little fingers are growing nails now. The baby probably will double his length this week. The irises of your baby's eyes are developing now.

13. Week Twelve  The baby's chest is rising and falling as it practices breathing movements..  With kidneys that are fully functioning the baby can swallow amniotic fluid and excrete it as urine.  The amniotic fluid is completely replaced every 3 hours, so the baby's environment stays fresh. Even though she is not eating yet, the baby's intestines are contracting in peristaltic movements as if she were digesting food

14. Teratogen ~Thalidomide - This drug was used to control nausea during pregnancy -Thalidomide was used in the late fifties and removed from the market in 1961 -Thalidomide causes deformities in the developing fetus.

15. - Deformities such as defective intestines, hearing defects or no ears at all, and impaired vision. -Many of the foetuses were born with undeveloped limbs or no limbs at all.

16. ~Radiation ~Radiation There are a number of ways to be exposed to radiation: having a medical X-ray, working at a nuclear power plant, working in any industrial setting where X-rays or with other radioactive substances. Countless other minor sources such as TVs, smoke detectors, and airplane trips. Radiation exposure at high enough levels can cause developmental risks to a developing fetus like a reduction in height, severe mental retardation, small head size, impaired brain development, childhood leukemia, and cancer in later life. There are a number of ways to be exposed to radiation: having a medical X-ray, working at a nuclear power plant, working in any industrial setting where X-rays or with other radioactive substances. Countless other minor sources such as TVs, smoke detectors, and airplane trips. Radiation exposure at high enough levels can cause developmental risks to a developing fetus like a reduction in height, severe mental retardation, small head size, impaired brain development, childhood leukemia, and cancer in later life.