Date of conception

Online calculator of the date of conception

• 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 woman’s last period, not the date of conception which generally occurs two weeks later.
• Since some women are unsure of the date of their last menstruation (perhaps due to period irregularities), a baby is considered full term if its birth falls between 37 to 42 weeks of its estimated due date.