Biology » The Reproductive System » Human Pregnancy and Birth

Summarizing Human Pregnancy and Birth


Human pregnancy begins with fertilization of an egg and proceeds through the three trimesters of gestation. The labor process has three stages (contractions, delivery of the fetus, expulsion of the placenta), each propelled by hormones. The first trimester lays down the basic structures of the body, including the limb buds, heart, eyes, and the liver. The second trimester continues the development of all of the organs and systems. The third trimester exhibits the greatest growth of the fetus and culminates in labor and delivery. Prevention of a pregnancy can be accomplished through a variety of methods including barriers, hormones, or other means. Assisted reproductive technologies may help individuals who have infertility problems.



(also, birth control) various means used to prevent pregnancy


length of time for fetal development to birth

human beta chorionic gonadotropin (β-HCG)

hormone produced by the chorion of the zygote that helps to maintain the corpus luteum and elevated levels of progesterone


inability to conceive, carry, and deliver children

morning sickness

condition in the mother during the first trimester; includes feelings of nausea


organ that supports the diffusion of nutrients and waste between the mother’s and fetus’ blood

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