When is baby due?

by - December 04, 2023

When people find out I'm pregnant, there are one of two questions they will ask first:

  1. When is baby due?
  2. Do you know what you're having?

When is baby due? Well, nobody really knows because estimated due dates based on the start of your last menstrual period are based on a very non-inclusive formula some German obstetrician named Franz Nagele concocted hundreds of years ago, assuming all menstrual cycles are 28 days long and you conceived on day 14. This excludes most pregnancies because menstrual cycle lengths vary and you can conceive on a number of fertile days each cycle. In short, this method is stupid and I don't understand why we still use it.

Healthcare professionals realise this, which is why some medical practitioners use your Week 12 growth scan to estimate a new due date that they deem more accurate. But this method is also flawed because the angle the sonographer decides to take the measurement on any given day changes, your fetus's position could also be tricky to measure and you end up with a measurement that can be a little or a long way off the reality.

Lastly, we started the IVF process and my hormones were all over the shop when we became pregnant naturally. My menstrual cycle was a whopping 49 days or so the month before we became pregnant as opposed to my usual 28-day cycle. I tracked my body's symptoms and knew when I had spot bleeding, which I thought was my period coming in a few days, but it turned out to be Baby Pham in embryo form embedding into my uterus lining so if I use another formula that assumes the embryo implants 6-7 days after fertilization then my current estimated due date is off by over a week.

So when people ask me when baby is due, I say it'll be a summer baby.

This turned into a long rant, so I will talk about gender reveals in my next post.

Our fertility and pregnancy experience

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