How Is Due Date Determined?
After seeing that positive pregnancy test, most women have one big question on the brain, “When is my baby due?” Calculating your due date is easy, as long as you know at least one of three key dates: the first day of your last period, the date of conception, or the date of your IVF transfer (if applicable). With these three specific days in mind, you can easily calculate your baby’s due date. Keep reading to calculate your due date below!
First Day Of Last Period
Generally speaking, most pregnancies will last a total of 48 weeks (or 38 weeks from conception). With that in mind, the best way to estimate your exact due date is to count 40 weeks, or 280 days, from the first day of the last menstrual period you had. Another way to calculate the due date is to subtract three months from the first day of your last period and then add seven days.
Let’s say your last period started on March 3rd, you’d count back three months to December 3rd and then add seven days. This means your due date would be December 10th. This is how your doctor will estimate your due date as well. However, it is normal to deliver a week or two before or after that date.
After seeing that positive pregnancy test, most women have one big question on the brain, “When is my baby due?”
Conception Date
If you’re unsure of the first day of your last period or have irregular menstrual cycles, you may be able to calculate your due date based on the conception date. If you remember your exact conception date, just add 266 days to that number. You’ll get your estimated delivery day. In this case, if your conception day was on April 11th, your estimated date of delivery would be January 2nd. Easy right? Now start crunching those numbers.
IVF Transfer Date
In recent years, more and more couples have started to rely on assisted reproductive technology to conceive. If you’re one of 77,000 women who are due to give birth thanks to ART this year, you’ll want to have your exact IVF transfer date handy to calculate the due date. For a 3 day transfer, use the retrieval date and then add 266 days.
Then, you will need to subtract three days for the embryos. If you underwent a 5-day transfer, use the retrieval date and then add 266 days. Then you will need to subtract 5 days for blastocysts. You can also use your embryo transfer date and then add 261 days.
Keep in mind, though due dates can be accurate, it is not uncommon to go into labor or be induced up to two weeks before or after that calculated date. In other words, be prepared well before the date you have in mind!
Many doctors tell patients to develop their birth plan at least six weeks in advance of their actual due date. This can help patients to prepare for whatever life throws their way and the event of an unexpected early delivery!
