Pregnancy Due Date Calculator
Estimate your baby's due date based on your last period.
How Due Dates Are Calculated
Most due dates are estimated using Naegele's Rule, which assumes a 28-day cycle. The calculation is: Start from the first day of your last menstrual period (LMP), add one year, subtract three months, and add seven days.
Pregnancy Trimesters Guide
- First Trimester (Weeks 1-12): Crucial development. The baby's heart begins to beat, and major organs start forming. Hormonal changes often cause nausea (morning sickness).
- Second Trimester (Weeks 13-27): Often called the "honeymoon phase." Nausea usually subsides, you often feel more energetic, and you may feel the baby move ("quickening").
- Third Trimester (Weeks 28-40): Final growth stretch. The baby gains significant weight. You may experience back pain, heartburn, and difficulty sleeping as your belly grows.
Is the Date Exact?
Only about 4% of babies are born on their exact estimated due date. Most are born within two weeks before or after. Your provider may adjust your due date based on an early ultrasound measurement.