Your estimated due date is
How is this calculated?
To calculate your due date, your health care provider will count ahead 40 weeks from the start of your last period. When your baby arrives, it will have been about 38 weeks since he or she was conceived- but your pregnancy will have "officially" lasted 40 weeks.
Estimating your due date is an important part of your prenatal care, but there are no guarantees. Only an estimated 5 percent of babies are born on their due dates. It's just as normal to deliver your baby a week or two before — or after — your due date.