How is 40 weeks of pregnancy calculated?

Question

Doctor gave me a due date but the maths is confusing me. My actual conception was later than my last period so how does 40 weeks even work? someone pls explain in easy words

Minakshi Tripathy · Answer

Counted from first day of last period, so 280 days roughly. Thats why they always ask ur LMP. And dont fix on the exact date, very few babies arrive bang on 40 weeks, both mine came a bit early.

Karishma Bhatia · Answer

I was confused by this too! So the 40 weeks starts from last period date, that explains why my doctor asked that on the first visit. Makes sense now.

Avani Narang · Answer

Yeah its calculated from ur last menstrual period date. I just put my LMP into a due date calculator app and it gave me the 40 week timeline instantly. The dating scan later confirmed it pretty closely.

Chandni Majumdar · Answer

From the first day of ur last period, count 40 weeks. Thats how the due date comes.

Janaki Nanavati · Answer

My doctor explained it counts from the first day of ur last period, not from conception. So the first two weeks ur not even pregnant technically, but thats the standard way. 40 weeks from that date is ur due date.