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.
Coding for Prematurity. For The Record. Vol. 20 No. 14 P. 28. A normal, full-term pregnancy typically lasts 40 weeks. A premature birth takes place more than three weeks before the 40th week. On the motherâs record, premature birth is classified to ICD-9-CM code 644.21.