PSYB32H3 Chapter Notes - Chapter 3: Parasitic Disease, Infant Mortality, Syphilis
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Conception takes place during a woman"s ovulation or within a few days of it; the ovum, or egg, once released from the mother"s ovaries, lives only about three to five days. Prenatal development then encompasses the 38 weeks or approximately 9 months, between conception and birth. Traditionally, pregnancy has been described as occurring in three trimesters, three periods of three months each. When this occurs, about one week after conception, the zygote is very small. During this period the embryo becomes recognizable as a tiny human. During this period the infant increases 2 million percent in size. During this fetal period the development of bodily structures and systems becomes complete. At the end of the third month the fetus has all of its body parts, by the end of the fourth month mothers usually report movement of the fetus. At around five months, reflexes such as sucking, swallowing and hiccupping, usually appear.
