Pregnancy Due Date
A typical pregnancy lasts, on average, 280 days or 40 weeks - starting with the first day of the last normal menstrual period (LMP) as Day 1. An estimated date of delivery (EDD) can be calculated as follows:
- determine the first day of your last menstrual period
- count backwards three calendar months from that date
- lastly, add one year and seven days to that date
- here’s an example: your last menstrual period began on July 19, 2003; three months prior to that month would be April 19, 2003. Adding one year and seven days will give you your pregnancy date: April 26, 2004.
- this number just gives you an approximation, since few women actually give birth on their calculated due dates. Anytime two weeks before or two weeks after the due date is considered a normal pregnancy.
Other ways to estimate your due date or how far along you are in your pregnancy include:
- the size of your uterus; the uterus size conforms to the stage of pregnancy you are in
- the first time the fetal heartbeat is heard with a Doppler device normally occurs at 10-12 weeks of pregnancy
- the top of the uterus, known as the fundus, will reach the bellybutton at about week 20
Calculate your conception date as well as your due date with our Pregnancy Calculator
Revision date: July 5, 2011
Last revised: by David A. Scott, M.D.