Why do pregnancies start counting from the last day of your period instead of the day of conception?

Question

Also, how accurate is the due date?

In: 801

Answer 1

It probably *should* be counted from the date of fertilization, but that’s pretty much impossible to determine, so the last period date is a decent guess.

And the due date is nothing more than an educated guess as well, so it doesn’t really matter very much for any practical reason.