Skip to Content

Committed to Safety: As we resume services, we are taking all necessary precautions to keep you safe while we care for you. Limited visitation is now in place. Review all our visitor policies and precautions. Get more information on COVID-19.

Due date

A due date is an estimate of when a pregnant woman will have her baby. It is calculated by taking the first day of her last menstrual period (LMP), adding 7 days, and then counting backward 3 months; or by adding 40 weeks from the first day of the last menstrual period (for women with regular 28-day cycles).

For example, using the first method, if a pregnant woman's last period started on March 20, add 7 days to get March 27 and then subtract 3 months to get a due date of December 27. Using the second method, 40 weeks counted from March 20 is December 25.

Ultrasound is often used to estimate a due date based on the size of the fetus.

The due date is only an estimate of when a woman will deliver. Most women do not give birth on their due date, but they do within 2 weeks before or after.

Wellness Matters

Subscribe to our Wellness Matters e-newsletter, a monthly snapshot of the some of great wellness content from Cone Health providers.

Subscribe Now

Health Library

  • Due date