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  • Writer's pictureAnxious Kat

Calculating due dates before pregnancy and other math problems

Warning: There is math in this post -- very simple math. But hang in there!

On the first day of my period, every cycle, I immediately look up the potential baby due date.

Due date calendars are my weakness. I'm not even pregnant yet but for some reason, I need to know right now when I will have this hypothetical baby. Like, I am actively having my period and I am already planning and predicting for the next round.

Due date dance

First, I go to the "first day of your last period" option, because calculating pregnancy/due dates is just pure fuzzy math. My sex education was so bad that I thought 4 weeks pregnant actually meant 4 weeks -- but technically it is much earlier.

It very much irritates me but the odds of everyone knowing when they conceived probably isn't that high. However, if you are a crazy tracker like me, you know the SECOND you conceived. You either pre-logged it (nothing is sexier than scheduling sex) or you quite literally rolled over, grabbed your phone, and logged it in.

Now, after I peek at the period-based prediction date, I go for the conception-based prediction date, especially if I don't like the first date. What signifies a bad date? No idea, but apparently I never like the first date. Or maybe I just like calendars, who knows.

The number one thing I am looking for is if I am at risk of having a holiday kid. I have a friend who was born on December 26th. Every Christmas, she feels robbed -- less gifts and no one is going to be showing up for a day-after-Christmas birthday party.

Implantation calculations

Ok, so ovulation is over and now it's time for the dreaded 2-week wait and the days past ovulation calculations begin. DPO numbers become life. Not only that but implantation becomes a main focus.

Now, before that sperm can even reach that egg, I am already in Google looking up this chain of questions that I ask EVERY MONTH. And Google doesn't even wait for me to finish my sentence. Shut up, Google -- you don't know me!

The ultimate question: When does implantation [fill in the blank].

Now, the DPO math begins.


There is no clear answer, there never is. Some sites say implantation occurs 6 to 12dpo, others say 8 to 10dpo. Personally, I like to go for 9 -- seems like a good number based on very little scientific research.

Then, 7 to 12 days after implantation, a woman starts producing hCG. So, the median of those days is 9.5 -- so let's round down to 9 because it's an awesome number.

So, if implantation happens on day 9, and then we wait 9 days to finally test for HCG, that means the best day to test to see if you are pregnant is...

Fuck math and science. I'm testing at 5dpo.

*Image from: This Is Your Year...Probably calendar by Loz Ives at Idle Letters

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15 mar

Embark on the amusing journey of due date predictions and conception calculations with a touch of humor and a sprinkle of math. Dive into the entertaining world of pre-conception planning and ovulation tracking at Pregnancy Calculator and discover the joy of anticipating the arrival of a hypothetical baby while mastering the art of fuzzy math and witty commentary

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