how many weeks are you pregnant for

Pregnancy is typically counted as lasting about 40 weeks, starting from the first day of the last menstrual period (LMP), not the day of conception. This method includes approximately two weeks before actual conception occurs. The range for a normal pregnancy duration is usually between 37 and 42 weeks. Pregnancy weeks start counting from week 0 on the first day of the last period, and the due date is generally estimated as 280 days (40 weeks) from this day. This calculation can be refined with ultrasound scans for a more accurate estimate. Births often occur anywhere from 37 to 42 weeks, and few happen exactly on the due date. In summary, pregnancy is considered to last around 40 weeks from the last menstrual period but can vary from 37 to 42 weeks for a full-term pregnancy.