Shephard, Bruce D. American College of Obstetricians and Gynecologists, Tampa Obstetrics and Gynecology Associates, Tampa, Florida.
Last reviewed:March 2020
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- Establishment of pregnancy
- Embryonic development
- Prenatal care
- Safety and postnatal care
- Termination of pregnancy
- Related Primary Literature
- Additional Reading
The period during which a developing fetus is carried within the uterus. In humans, pregnancy averages 266 days (38 weeks) from conception to childbirth. Traditionally, pregnancy duration is counted from the woman's last menstrual period, which adds roughly 2 weeks to the gestational age. This is how physicians arrive at a pregnancy length of 40 weeks (280 days). The 9 months of human pregnancy are typically divided into three periods (trimesters) of 3 months each (Fig. 1). See also: Animal reproduction; Gestation period; Uterus
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