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.
The average pregnancy is calculated at 40 weeks (or 280 days) from the start of your last menstrual period (LMP). Remember, babies rarely keep to an exact timetable, so a full-term pregnancy can be anywhere between 37 and 42 weeks.