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Due Date

Due Date Calculator
When did your last period start?
Generally, how long are your cycles?
Calculate your due date
Your baby is likely to be born on or around*
*Only your physician can accurately determine your due date or the date of your conception based on his/her knowledge of your complete medical condition.
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In partnership with Clearblue®.

Making use of the due date calculator

Enter the starting day of your last period and click'show your due date' to get your due date. Pregnancy usually lasts between 37 and 42 weeks from the first day of your last menstruation.
To use this calculator, you must know the beginning day of your last menstruation. If you don't know or are unsure, see a midwife or a doctor.
Your midwife will offer you a 12-week scan as part of your pregnancy (antenatal) care, which may give you a more exact date for the birth of your baby.

How is my due date determined?

There are various options. If you know when you conceived, you may calculate your due date by counting 38 weeks from that day. (A human pregnancy lasts around 38 weeks.)
However, only a small percentage of expecting mothers know the actual day of conception. Even if you just had intercourse once throughout your fertile period, unless you were ovulating, you would not conceive on that day. Sperm can survive in your fallopian tubes for up to five days. So, it's possible that you'll release an egg (ovulate) up to five days after having sex before it's fertilized by a waiting sperm. That is the day you get pregnant.
So, how can one calculate a due date without knowing the day of conception?

The first day of your last period

The most popular method for calculating your due date is to count 40 weeks from the beginning day of your last menstrual cycle (LMP). That is how the majority of healthcare providers operate.
If your menstrual cycle is the typical length (28 days), your period probably began approximately two weeks before you conceived. This explains why pregnancies are supposed to last 40 weeks rather than 38.
This approach does not consider how lengthy your menstrual cycle is or when you believe you may have conceived. But generally speaking, women often ovulate approximately two weeks after their menstrual cycle starts. Women, on the other hand, are more likely to remember when their previous menstruation began than the day they ovulated.

Date of conception

If you know exactly when you conceived – for example, if you used an ovulation predictor kit or kept track of your ovulation symptoms – you may determine your pregnancy due date based on your conception date. Simply select that calculating technique from the pulldown menu above and enter your date.
Again, you don't always conceive on the day you have sex. However, for a lighter read, check out our stories from parents who knew exactly when and where they performed the deed that resulted in their kid.

Is it possible to arrange my due date?

You can try to timing when you conceive in order to “plan” your due date if you want to avoid being very pregnant in the thick of summer or if you're a teacher who wants to optimize time off with your child. Even if you're one of the lucky ones who can get pregnant whenever she wants, keep in mind that you won't be able to plan out exactly when you'll give birth to the day (or even the week or month!).
You may still use our Ovulation Calculator, which utilizes the date of your last menstrual period and your average cycle length to determine the days you're most likely to be fertile and boost your chances of conceiving.

Can my due date change?

Yes, your due date is subject to change. While it's rarely cause for concern, your doctor may adjust your due date as your pregnancy advances for a variety of reasons.
It's possible that you have irregular periods and your early ultrasound date was incorrect, or that your first ultrasound was performed in the second trimester.
It might possibly be because your fundal height is abnormal or your levels of alpha-fetoprotein (AFP), a protein produced by the baby, are higher than normal. If you have any questions or concerns, speak with your practitioner.
If your baby is determined to be substantially larger or smaller than predicted for gestational age during a first trimester ultrasound examination, your due date may be revised. This is more likely if you have an unusual menstrual cycle length that makes determining the date of conception difficult.
During the ultrasound test, your healthcare practitioner will measure your baby to determine how far along she is and will then give you a new due date.