Baby measuring being at anatomy scan?

knottie3dd327872de786e8

Based off my LMP (12-13-22) , I’m almost 18 weeks pregnant. I went for an anatomy ultrasound today, and found out my baby was measuring at 16 weeks and 3 days. Which is more accurate to go by, my LMP or the ultrasound scan? I know for a fact when my period was, and my periods are pretty regular! This has thrown me for a loop because my due date could change by two whole weeks. I had one ultrasound in my first trimester (which I heard were more accurate), but doctor couldn’t get the measurements then. I am not understanding, if all babies are different and grow differently, why are we going off a second trimester ultrasound instead of LMP when my cycles always been regular.

linh18

Ask your doctor. Everyone has a different cycle and when they ovulate so you could've ovulated  later than you thought. Two weeks sounds like a lot but if your doctor is sticking with the ultrasound dating you should too. (Plus chances are with a first(?) pregnancy you might deliver at full term, late term anyways, so it's better than thinking you are 42 weeks when you might really only be 40) Usually dating ultrasounds are most accurate in the middle of the first trimester like you said, but it sounds like that wasn't an option. I'd say go with whatever your doc tells you, though it's probably a little disappointing expecting baby to be older than they say they are. You still have lots of time and maybe another later ultrasound/exam will even things out a bit anyways? 

Wishilivedinflorida

Ultrasounds are less accurate for dating as time goes on. Typically an anatomy scan is not used to change EDD because of this. Check with your provider, but odds are they will keep your original EDD. If you didn’t get an early dating scan, they will probably go by LMP still. 

jamigs1

Was it you who posted you’re a smoker? This could be why you’re measuring smaller.