Our pregnancy calculator is a simple tool which helps you work out your approximate due date before you get a more definite answer at your dating scan, which happens when you are around 12 weeks pregnant. How does the pregnancy due date calculator work? Working out how many weeks pregnant you are can be a little confusing. Until your dating scan your pregnancy will be counted from the first day of your LMP last menstrual period , although ovulation will generally occur two weeks after your LMP, which is when you technically become pregnant. In simple terms, your due day is the first day of your last period, plus 40 weeks. Is the pregnancy calculator accurate?
Pregnancy Due Date Calculator | Pregnancy Calculator | Mother&Baby
Dating your Pregnancy The 40 week countdown You can calculate your due date by subtracting three months from the first day of your last menstrual period LMP and then add a week. Use our pregnancy calculator. A pregnancy is based on being days long, which is 40 weeks more like 10 months not 9! When we give you a due date we consider 37 to 42 weeks to be full-term, so even if your baby is born two weeks before your due date it is not considered premature. Because few women know the exact day they ovulated or conceived, an ultrasound done in the first trimester of pregnancy has been shown to the be the most accurate way to date a pregnancy.
The tendency for multiple gestations to be delivered earlier than singleton pregnancies should not be interpreted that multiples should be assigned an earlier estimated due date. Review by Mark Curran, M. How accurate is fetal biometry in the assessment of fetal age?. Am J Obstet Gynecol ; Estimating the date of confinement:
Pettker, MD; James D. Goldberg, MD; and Yasser Y. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change.