Pregnancy Due Date Calculator

Pregnancy Due Date Calculator

This calculator uses Naegele's Rule, the standard clinical method for estimating the expected date of delivery (EDD).

The Medical Logic

A normal pregnancy lasts about 40 weeks (280 days) from the first day of your last menstrual period (LMP). Note that only about 4% of babies are born on their exact due date; the EDD serves as a crucial milestone for prenatal care milestones.

Understanding the Trimesters

1. First Trimester (Weeks 1-12): Rapid development; critical organogenesis.
2. Second Trimester (Weeks 13-26): 'The Golden Period' where energy often returns.
3. Third Trimester (Weeks 27-40): Final growth and preparation for birth.

Important Note on Accuracy

An ultrasound conducted in the first trimester is the most accurate way to date a pregnancy. If your doctor provides a date based on an ultrasound, that date should take precedence over calculations based on LMP, especially if your cycles are irregular.