1. Development of Babies in the Womb

2. There are steps in development A baby’s development begins in the womb. There are three trimesters, during which development occurs. There is the first trimester, the second trimester, and the third trimester. Each trimester is around three months. During the set of weeks and even individual weeks within the trimesters development occurs.

3. The development of a baby

4. First Trimester The first trimester is an important trimester. The baby begins its growth and develops.

5. Weeks 1-4 The first trimester begins with fertilization, the pre-embryonic stage, and formation of the embryo. Fertilization will occur within the second week and by the third week the egg is fertilized and completely fused to the uterus wall. Between weeks three and four, cells in the embryo multiply and form three separate layers each with their own purpose.

6. The Endoderm Layer The first layer is the endoderm and it will consist of the baby’s gastrointestinal tract and endocrine glands.

7. The Ectoderm Layer The second layer is the ectoderm. The ectoderm will become the skin as well as the nervous system.

8. The Mesoderm Layer The third and final layer is the mesoderm. This layer will develop into the connective tissues, circulatory system, skeleton, and muscles.

9. End of the First Month

10. Weeks 5 - 8 During week five specialized cells develop that will become the vital organs such as the heart, brain, liver, spinal cord, and kidneys. Facial features begin to appear and indicate the start of ears, eyes, and a nose. Week six comes and organs still continue to develop. The formation of a rudimentary mouth initiates. In the conclusion of the sixth week the embryo has a heartbeat. Refinement of nervous system occurs during week seven. The brain attains ten nerve pairs and five areas of specialized cells. Nerves are in the process of fashioning in the newly forming muscles. Facial features deepen and limb buds exhibit. Paddle shaped appendages known as embryonic hands and feet become evident.

11. Fetus at week 6

12. Week 9 – 14 The anatomy becomes more recognizable between weeks nine and ten as the features become more distinct. Reproductive and urinary organs form. From weeks eleven to fourteen the fetus has a profile. Eyelids are fused shut and the jaw can move.

13. The Second Trimester The second trimester is one of refinement. The organs and everything else refine.

14. Weeks 15 - 18 The second trimester begins with weeks fifteen to eighteen. The fetus looks human and all major organs are functioning. The fetus can stretch, move, and the gender can be identified. Hair known as lanugo grows on the head. The first feces accumulate in the bowl.

15. Weeks 19 - 22 As weeks nineteen to twenty-two pass the fetus will grow bigger. Muscles will get stronger and dentine forms on the teeth. The immune system begins developing and antibodies can be detected. A sleep-wake cycle is established. Eyelashes, nipples, and eyebrows appear. Vernix, a natural lotion, begins to coat the skin.

16. Second trimester

17. Weeks 23 - 27 From weeks twenty-three to twenty-seven the body becomes proportional. Feet and fingerprints form and the hands can make grasping motions. The fetus is more active and can sense sound and some light.

18. Third trimester The third trimester is one of rapid growth. The baby will grow tremendously in preparation for being born.

19. Weeks 28 - 30 By week twenty-eight and till week thirty, the third trimester begins. The fetus will fill out and its weight can increase up to five-fold. Nostrils open and respiration becomes more rhythmic and coordinated. Alveoli form inside the lungs and make it possible for the fetus to correctly breathe. The fetus breathes amniotic fluid and expels it to stimulate development. The fetus will react to outside sounds and the eyes will open and close.

20. Week 28

21. Weeks 31 - 40 Weeks thirty-one to forty bring the final developments and refinement of everything and the body temperature regulates. When week forty comes the baby should be born, if it is not already, and begin its development outside of the womb and in the world.

23. Baby at birth

24. Citation Preston, Penny. What Every Mother Needs to Know about Her Baby's First Year. Portland, ME: Ronnie Sellers Productions, 2006. Print. Truman, Lucy. The Birthing Cycle: What a Woman Needs to Know about Her Pregnancy. Portland, Me.: Ronnie Sellers Productions, 2004. Print. "Fetal Development Week by Week." BabyCenter. BabyCenter LLC, n.d. Web. 06 Nov. 2013..