Is it time to break up with your due date?
Our culture has a passionate love affair with the estimated due date. I mean – we don’t just love it. We wine and dine it and send it roses on Valentine’s Day.
The first thing you do when you find out you're pregnant? Find a due date calculator to figure out when your baby will be here.
The first question you're asked when others find out you're expecting? “What's your due date?”
Image description: a parent holds their new baby, facing the camera. The baby is yawning.
Once you have that date, you put it in your calendar, look forward to it, wait for it, count down to it, and (heaven forbid!) if you go past that date you'll often feel anxious (at best) or full blown panic (at worst).
Care providers use it to decide how long is “safe” to continue being pregnant and to make other clinical care recommendations for you and your baby.
We're IN LOVE with due dates.
But it may be time to break up with them. Here's why (1):
The way we calculate modern day due dates is based on a study done on 100 women in the 1700s.
Right?!
So, this guy named Hermann Boerhaave came up with a way to calculate due dates based on the records of 100 pregnant women in 1744.
In 1812, this OTHER guy Carl Naegele quoted Boerhaave's work which is how this way of calculating due dates became known as Naegele's Rule.
Unfortunately, neither of them clarified if their calculation method should be done from the FIRST day of your last menstrual period (LMP) or the LAST day of your LMP.
Then, in the early 1900s, American obstetrics text books randomly decided that due dates should be calculated using Naegele's Rule from the FIRST day of your LMP.
The most commonly used method for calculating due dates today is basically the result of the worst game of telephone ever.
Okay, so is there a better way to estimate your due date?
There is! Well, sort of.
The current (modern 😏) evidence we have indicates that a dating ultrasound done between 11-14 weeks gestation gives the best estimate of when your little one will arrive.
The kicker? Best estimate = 68% of people who have an early dating ultrasound between 11-14 weeks gestation will give birth within plus OR minus 11 days of their due date. That's closer to a due month than a due day.
Everything I've ever believed is wrong! Are pregnancies even 40 weeks long?
Ummm...nope. The average length for pregnancy for first-time birthing folks is 40 weeks and 5 days and for second-time birthing folks is 40 weeks and 3 days.
Ugh. What am I supposed to do with this information?
Dearheart - it's time to break up with your due date, for your own mental and emotional well-being.*
Now's the time to start thinking of it more as a "due window" - a period of time covering several weeks during which your baby will decide to make their entrance.
That way, when that date on your calendar comes and goes, you'll know it's actually no big deal.
Make yourself a nice cuppa, hop in the bath, and listen to your favorite music. Let your baby know you're excited to meet them - as soon as they're ready.
(*If there is a medical concern or indication that it might be time to help baby along, your care provider will discuss that with you. Take the time to ask any questions you have and to make the decision that is best for you.)
OH! One last thing - even though you now know that estimated due dates are basically useless, not everyone around you will. And in their excitement to celebrate your new arrival, you may start getting a lot "Have you had that baby yet???" inquiries in the last weeks of your pregnancy.
If that happens, just send them here.
Want a team of doulas ready to support you as you approach your "due window"?
Need a doula to rant to about Aunt Karen who will. not. stop. asking. if. the. baby's. here. yet?
Wondering if people REALLY eat their placentas? We've got you covered!
(1) Dekker, R. (2020, February 25). The Evidence on: Due Dates. Retrieved May 21, 2020, from https://evidencebasedbirth.com/evidence-on-due-dates/
