How to check pregnancy date?

Question

I am confused whether pregnancy date is counted from last period or the day we had sex. My app shows one week more than what I expected. How do doctors calculate it?

Renu Deshmukh · Answer

I just put my last period date in a pregnancy app and it showed my weeks and due date instantly. But at the first scan the doctor corrected it slightly, so trust the scan over the app na.

Sandhya Sen · Answer

Easiest way they count is from the first day of your last period, then add 40 weeks. But the early ultrasound dating is the most accurate one, my doctor went by the scan. Both together give your due date.

Rajalakshmi Namboothiri · Answer

Same doubt i had! They asked me my last period first day and calculated from there. Then dating scan gave the exact week. If your periods are irregular like mine, the scan is more reliable.

Kanika Pillai · Answer

Note your last period's first day, thats the starting point. Then the first ultrasound confirms how far along you are. Simple, dont overthink it.

Romila Murugan · Answer

We count from last period date at home, but i always tell to confirm with the doctor's scan. The ultrasound in early weeks tells the proper date and due date. Family guesses are fun but scan is final.