When is your baby due? Enter your last menstrual period and find out instantly.
Frequently Asked Questions
Due date calculators using Naegele's rule are accurate to within about 2 weeks for women with regular 28-day cycles. Only about 5% of babies are born on their exact due date. Your healthcare provider may adjust your date based on ultrasound measurements.
Naegele's rule is the standard method for estimating pregnancy due dates. It was developed by German obstetrician Franz Naegele in the early 1800s. The formula adds 280 days (40 weeks) to the first day of your last menstrual period. It assumes a 28-day cycle with ovulation on day 14.
If you don't remember your LMP, your healthcare provider can estimate your due date using an ultrasound measurement. First-trimester ultrasounds (before 13 weeks) are the most accurate for dating, typically within 5-7 days.
Yes. Your due date may be adjusted after an ultrasound if the baby's measurements differ significantly from what's expected based on your LMP. This is especially common with irregular cycles. Trust the date your provider gives you.
Full term is 39 weeks 0 days through 40 weeks 6 days. Early term is 37-38 weeks, late term is 41 weeks, and post-term is 42+ weeks. Babies born within the full term window generally have the best health outcomes.
Pregnancy is actually counted from the first day of your last period, not from conception. So during the first two weeks of pregnancy, you aren't actually pregnant yet.