How can I predict my due date?
First day of last period
The best way to estimate your due date is by counting 40 weeks or 280 days from the first day of your LMP (Last Menstrual Period) - assuming a 28-days cycle. And this is how most doctors calculate your due date.
This method is based on the idea that ovulation or conception usually takes place about 2 weeks after your menstrual cycle starts, and a normal pregnancy lasts about 38 weeks, from conception to childbirth. Plus, it’s much easier to remember the first day of your LMP than to figure out your conception date.
Note: The LMP method works well only if you have a regular menstrual cycle.
If you remember the date you conceived, you can get your estimated due date by adding 38 weeks or 266 days to that date. You can tell exactly when you conceived if you know your ovulation date. For this, you can use an ovulation predictor kit or keep track of your ovulation symptoms.
Note: You don’t necessarily conceive on the day you have sex. Sperm can live in a woman's body for up to 5 days. So, it may be possible that you ovulate and get pregnant 5 days after you have sex. That’s your actual conception date.
Can my due date change?
Yes, your estimated date of delivery (EDD) can change. As your pregnancy progresses, your doctor may change your estimated due date based on your first-trimester ultrasound. This is more likely to happen if your periods are irregular, which makes it difficult to figure out the exact date of conception.
How likely am I to deliver on my due date?
Please remember that your due date is only an estimate. Only about 2-5% of women give birth on their due date. Around 80% of women give birth within the two weeks before or after.