Pregnancy Calculator

No, only about 4% of babies are born on the exact due date. Most are born within two weeks before or after that date.

This calculator uses Naegele's Rule: add 7 days to the first day of the last menstrual period, then subtract 3 months.

A pregnancy is considered "full term" between 39 weeks and 40 weeks and 6 days. Before 37 weeks is considered preterm.

Pregnancy Stages

Pregnancy is divided into three trimesters, each with specific developmental milestones:

1st Trimester (Weeks 1-12): Early development of vital organs and body structure of the baby.
2nd Trimester (Weeks 13-26): Rapid growth phase, baby movements start to be felt, and generally the most comfortable stage for the mother.
3rd Trimester (Week 27 to birth): The baby gains weight and prepares for birth.

Last Menstrual Period (LMP): January 1st

Naegele's Rule:

1. Add 7 days: 1 + 7 = January 8th

2. Subtract 3 months: January 8th - 3 months = October 8th

3. Add 1 year (if necessary)

Estimated Due Date: October 8th

Is the due date exact?

How is the date calculated?

What is a full-term baby?