How do you measure pregnancy weeks?

Question

First time pregnant and honestly the week counting is confusing me. My gynac said one number but i calculated from a different day and it doesnt match. Can someone explain simply how the weeks are actually counted?

Anita Arora · Answer

I just put my last period date into a pregnancy app and it showed my weeks and due date automatically. It updated every week which was lovely. But the scan is the final word on the dating.

Falguni Chetty · Answer

This confused me so much in the beginning, the week counting felt weird. So I was counted further along than I expected based on the period date. Did anyone else find this part confusing at first?

Arpita Ganguly · Answer

From the last period date, that's the trick.

Himani Panikkar · Answer

Weeks are counted from the first day of your last menstrual period, not from conception. So you're already counted as 2 weeks pregnant around the time you actually conceive. My doctor confirmed the dating using the early scan too.