Combine a little bit of math and a little bit of mystery and you’ll be able to determine your baby’s due date. You can use several ways to calculate your due date, but much like adults, babies have a way of arriving on their own schedule. A typical pregnancy takes 40 weeks, less time if you’re pregnant with multiples. Even if your baby comes early or late, knowing your due date gives you and your loved ones something to look forward to.
Determine what the first day of your last menstrual period was. Add 280 days (40 weeks) to that date to get your due date. This is the method most doctors will use to calculate your due date, but it’s only effective if you know the exact date of your last period. This calculation also assumes that a woman is only fertile one day a month, exactly in the middle of her monthly cycle. If you have irregular cycles, it can cause the prediction to be incorrect.
Have an ultrasound to take a peek into your baby’s world. An ultrasound, or sonogram, will allow the doctor to determine your baby’s gestational age, according to how developed it is. Ultrasounds are the ideal way to predict a due date if you don’t have periods or if you have irregular periods. If you don’t have a period because you’re breastfeeding an older baby, do not assume you cannot get pregnant.
Look up to the moon and take note of its phase. It might be full, just a sliver, or if it’s a new moon, you might not see it at all. Keep your eye on the heavens because once you see that phase of the moon pass 10 times, you’ll know your baby is just about ready to be born. Historically, women used this method and it can still be used as a pregnancy timeline today. In her book “The Thinking Woman’s Guide to a Better Birth” Henci Goer notes that a German obstetrician in the early 19th century defined a full-term pregnancy as “10 moon months.”
Count backward to calculate your due date, according to Naegle’s Rule. Again, you’ll need to know the date of the first day of your last period. On your calendar, count back three months. Add seven days, and you’ll have your due date.
How to Find a Pregnancy Due Date: