U. S. Sen. Hillary Rodham Clinton, D-NY, and, former President Bill Clinton, blow out the candles on a cake at Hillary Rodham Clinton's 59th birthday party at Tavern on the Green in New York, Thursday, Oct. 26, 2006.
The unborn baby spends around 38 weeks in the uterus, but the average length of pregnancy, or gestation, is counted at 40 weeks. Pregnancy is counted from the first day of the womanâs last period, not the date of conception which generally occurs two weeks later.
But remember -- you want to be sure you deliver a full term baby if possible. Pregnancy lasts for about 280 days or 40 weeks. A preterm or premature baby is delivered before 37 weeks of your pregnancy. 1  Extremely preterm infants are born 23 through 28 weeks.  Moderately preterm infants are born between 29 and 33 weeks.