How Can I Figure Out My Due Date?

Perhaps you just found out that you are pregnant and you have to wait two to six weeks before you see the doctor, which isn’t uncommon. You believe that things are going well but you are dying to figure out when your due date is and you can’t wait until you see your doctor. Or, maybe you are one of the many women that have been to the doctor but you don’t agree with the due date for one reason or another. Lucky for you, you don’t need a doctor to figure out your due date, you can do it on your own and it’s actually quite simple.

To figure out your due date you will need to know the first day of your last period. You will then add seven days to that and subtract three months. When you subtract the three months that will be your due date! How simple is that? Another way to do it is to add 280 from your last menstrual period and you’ve got your due date. They will come up with the same answer so whatever is easiest for you will give you the information you are anxious for.

It’s important to note that this basic due date calculation is based on the average 28 day cycle. You will need to add the days to adjust for when you would have ovulated. If you know the last date of ovulation you can count forward 266 days from that date and you will arrive at your due date regardless of how many days are in your cycle. Of course, this method of calculation assumes that you were trying to get pregnant and you know exactly when you ovulate as a majority of women don’t know unless they are tracking their fertility.

If you want a quick way to determine when you due date would be you can always use one of the many quick calculators that will do all of the adding and subtracting for you in seconds online. These calculators are usually very accurate and use the same methods as we’ve discussed here. While you may figure out your due date on your own, the date that your doctor gives you will be the official due date so if it is different than yours you should go by that instead.

While all of these methods of due date calculation work really well and do not require you to see the doctor to get the magic date you should remember that only 5% of women actually deliver on their due date. 95% of the women in the world deliver anytime from two weeks before their due date to two weeks after the due date. When your doctor gives you a due date based on your last menstrual cycle this typically will not change unless a huge discrepancy is seen with ultrasound measurements.

Leila Pereira
Leila Pereira
I work in occupational therapy and occupational science. I specialize in early intervention pediatrics for children from birth to three years old; with an emphasis on children with autism. My goals are to support the achievement of developmental milestones in your child while collaborating with caregivers & parents; including play skill development, education, leisure, rest and sleep, feeding, nutrition and social participation. Licensed by the California Board of Occupational Therapy

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