Pregnancy is an exciting time! Beginning on Week 1, your body and your baby will undergo an incredible transformation. Even early in your pregnancy, long before you’re showing or experiencing any of the symptoms associated with pregnancy, there’s a rush of activity going on that affects virtually every part of your body.
By understanding these changes and knowing what you can do to help support yourself and your baby, you’ll be able to better handle the uncomfortable parts of pregnancy as well as give your baby the best chance for a healthy start in life. Research has shown that decisions you make even before pregnancy can have a lasting effect on your baby.
When does pregnancy begin?
Pregnancy technically begins at implantation—when your fertilized egg implants into the wall of your uterus—which is usually about five days after fertilization. The reason this is the medically accepted definition of pregnancy is because up to one half of fertilized eggs never implant. However, when your doctor figures your due date, he or she will work from your last date of menstruation, which is usually about two weeks before your egg was fertilized.
These two weeks are included in your overall pregnancy timetable, so a typical pregnancy lasts about 40 weeks, including these first two weeks. If you want to calculate your own due date, add 280 days to the date of when your last period began. Another quick way to do this in your head is to subtract three months from your last menstrual period and add seven days. This is the same method your doctor will use to calculate your due date.
“Having a pre-pregnancy visit can ensure you are doing everything possible to get your pregnancy off to its healthiest start.”
Reviewed by Dr. Jen Lincoln, November 2018