Track your pregnancy timeline and trimesters.
Estimated due date = LMP date + 280 days (40 weeks); trimesters are divided into roughly 13-week blocks.
A last menstrual period of January 1 gives an estimated due date around October 8.
It adds 280 days to the first day of your last menstrual period. Ultrasound dating in the first trimester is more precise.
The first trimester runs weeks 1–13, the second weeks 14–27, and the third weeks 28–40.
No. Due dates are estimates and only about 5% of babies arrive on the exact date. Consult your prenatal provider.
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