An obstetrician from the 1800’s decided your due date.

And VERY often babies are forced out of the womb before they’re ready based on his calculations.

The obsession with a gestation of 40 weeks leads to an increase in inductions, interventions, and surgical birth - all of which have physical and emotional/mental consequences for mother and baby.

But where did this guess date even come from?

The due date calculation we use today comes from an obstetrician named Franz Karl Naegele, who invented “Naegele’s Rule”. This calculation starts with the first day of your last menstrual period, goes back three months, then adds one year and 7 days. The result is a gestation of 280 days (40 weeks).

The 40 week date is an average, meaning that about 1/2 of people will give birth before that date, & 1/2 after. It probably wasn’t seen as a hard eviction date in the 1800’s.

But today we live in a fast-paced world that runs on schedules and money. And with the ability to “control” birth via induction and surgery, this 40 week average date often turns into the day when your baby will be forced from your body.

Here are my top 3 reasons why using this calculation as a hard eviction date is wrong...

1. Naegele’s Rule is based on a 28 day menstrual cycle. If you, like me, don’t ovulate at exactly day 14 of your cycle, this calculation won’t work for you. Most people don’t know when they ovulate, and this important fact is almost never taken into account when calculating a due date.

2. Our bodies are all different - we didn’t all get our periods at exactly age 11 years 6 months and 13 days, so why would our bodies all grow babies at exactly the same rate? To use a due date as an estimate of when a baby will arrive is one thing - to use it as an eviction notice is a completely different story.

3. Many factors determine whether you are likely to have a longer or shorter gestation - if you are between the ages of 19 and 34, having your first baby, or are white, you are statistically more likely to have a longer pregnancy.

Many women have their due date estimated with an early ultrasound, which can be more accurate than using Naegele’s Rule. That being said, your due date is always a guess, so take that into consideration if you start getting pressure as that date approaches.