Pregnancy Due Date Calculator
Calculate your estimated due date based on the first day of your last menstrual period (LMP). Also shows trimester dates.
How Due Dates are Calculated
The estimated due date is calculated using Naegele rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle with ovulation on day 14.
Only about 5% of babies are born on their exact due date. Most healthy births occur between 37 and 42 weeks of pregnancy. Your healthcare provider may adjust the due date based on ultrasound measurements.
Pregnancy Timeline
- First trimester (weeks 1-12): Major organ development, morning sickness common
- Second trimester (weeks 13-26): Baby movements felt, anatomy scan around week 20
- Third trimester (weeks 27-40): Rapid growth, preparation for delivery
Regular prenatal care is essential throughout pregnancy. Consult your doctor for personalized medical advice.
Frequently Asked Questions
How accurate is the due date calculator?
It provides an estimate accurate to within about 2 weeks. Only 5% of babies arrive on the exact due date. An early ultrasound can refine the estimate.
What if my cycle is not 28 days?
If your cycle is longer or shorter than 28 days, the due date may shift accordingly. A cycle of 35 days would push the due date about a week later.
Can the due date change during pregnancy?
Yes, your doctor may adjust the due date based on ultrasound measurements, especially if there is a significant discrepancy with the LMP-based estimate.