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pregnancy stages

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Human Sexuality
Banafshe Sharifian
May 1, 2012
Pregnancy is part of the process by which all sexual reproducing creatures continue the existence of their species. Pregnancy, in humans, is typically defined as beginning with the implantation of a fertilized egg in the uterus of a woman. This is after sperm has met and penetrated an egg in the woman’s fallopian tube (“Stages of development,” 2010). From there pregnancy is defined as the gestation period leading up to birth. Since all humans are born as a result of pregnancy, one could say that is a health topic that affects, or is related to, each and every person on the planet. However, it can more narrowly be said to affect women who are currently pregnant, those planning to become pregnant, and any partners they may have who are the fathers of their children or are otherwise invested in the pregnant woman’s life. This topic is a great interest to me because of the complexity of human development. At any point during a pregnancy, it seems as if there are so may things that could go wrong, it is a wonder how any have a positive outcome. However, it seems that the vast majority of pregnancies in the United States do have positive outcomes and the result is the ever expanding human family.

Pregnancy in humans is typically expected to last about 40 weeks and is typically measured in three trimesters. The first trimester occurs from the time of fertilization until about twelve weeks. The second trimester lasts from week 13 until week 28. Finally, the third, and last, trimester lasts from week 29 until birth (“Pregnancy,” 2010). Each of these trimesters is marked by specific stages in fetal development and requires that attention be paid to different aspects of prenatal care.

During the first few weeks of the first trimester of pregnancy – also called the germinal stage, in reference to fetal development – the fertilized egg implants itself in the uterus. Cell division typically begins within 48 hours of...