How to measure pregnancy weeks?

Question

My app is counting from last period but my scan report gave a different number. I am getting confused when people ask how many weeks I am. Which one do you usually follow?

Nita Gandhi · Answer

Don't worry too much about doing the math yourself. Tell your gynac the last period date and she'll tell you exactly where you are and your due date.

Geeta Singhal · Answer

It's counted from the first day of your last period, not from conception. So weirdly you're already '2 weeks pregnant' before you even conceive. Doc confirms exact dating with the early scan.

Architha Sundaram · Answer

Just put your last period date into any pregnancy app and it calculates the weeks and due date for u automatically. I used one and it was bang on with what my gynac said.

Subhadra Senapati · Answer

My doctor explained, they count from the first day of your last menstrual period (LMP) which makes 40 weeks total. If your cycles are irregular, the dating scan in the first trimester gives a more accurate week count. She said the early scan is the most reliable.

Ilakiya Krishnakumar · Answer

Count from first day of last period. Easy way to remember.

Hansika Maheshwari · Answer

I was so confused by this also! Turns out it's from the last period start date, so the number is more than how long the baby actually is. Did anyone else find it confusing in the beginning?