Pregnancy typically lasts about 280 days, which is equivalent to 40 weeks, counted from the first day of the woman's last menstrual period (LMP)
. This period includes roughly two weeks before conception actually occurs, so the fetus spends about 38 weeks developing in the uterus
. A full-term pregnancy is considered to be between 37 and 42 weeks
. Babies born before 37 weeks are classified as preterm or premature
. The due date is an estimate, and only about 4% of babies are born exactly on their due date
. In summary:
- Pregnancy duration: about 280 days or 40 weeks from LMP
- Actual fetal development: about 38 weeks from conception
- Full term: 37 to 42 weeks
- Preterm: before 37 weeks
This counting method is standard for healthcare providers to estimate due dates and monitor pregnancy progress
