due date calculator

frequently asked questions about due dates

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There is too much emphasis placed on due dates. The due date is actually just an estimation of when your baby will be born. The average length of pregnancy for first time pregnancies is slightly more than 41 weeks long

How is due date determined?

Your due date is 40 weeks or 280 days after the first day of your last period. It is based on a 28 day menstrual cycle. So if your cycles aren’t consistently 28 days, your estimated due date may be a little “wrong.” And even if you are regular, stress can delay ovulation.

Is ultrasound accurate for determining due date?

First trimester ultrasound is accurate for establishing due dates. The American Pregnancy Association says that the best time for calculating due date using ultrasound is between 8-18 weeks along. Second and third trimester ultrasounds are not appropriate for establishing an accurate due date.

I didn’t even have sex at the time that my doctor says I conceived. How can this be?

Sperm can stay alive for many days, so it is possible that you conceived several days after you had intercourse. Once you ovulate, there are only about 24 hours to conceive.

My doctor switched my due date after I had an ultrasound. What’s up with that?

Remember that due dates are determined by a 28 day cycle. If you ovulated later than what would occur with a 28 day cycle, your due date will be changed if an ultrasound shows a younger baby. Be wary of changing due dates based on weight or size of the baby late in pregnancy.

Do I need to be induced if I go past my due date?

There is a time and place for inductions, but some are not done for true medical reasons and can be harmful if the baby is not ready to be born. In fact, 50% of inductions on first time mothers end with cesarean for the simple reason that if the cervix isn’t ready dilate, it’s not going to open up and allow birth.

Dr. Bradley in Husband Coached Childbirth gives the example of an apple tree. Just like the majority of apples are ripe and ready to picked at a certain time, most babies are ready about 40 weeks gestation and are ready to be born. Some apples fall off the tree earlier than others and are perfect for eating, and a few babies are perfectly healthy a little early too. But some apples cling to the tree when all others are gone. If picked before ready, the apple will not be ripe and ready to eat. Some apples need longer time on the tree. Likewise, some babies need more time in the womb than others. Be very careful with inductions. You might force your baby to be born before he’s ready for life outside the womb.