Trimesters. By LMP or by Baby's Size?

Question

I am waiting for that miracle cure of a 2nd trimester to come. Based on my LMP i would be almost a week and a half further along than I am based on the gestational size of the baby via ultrasound. So what would the trimesters go off of?

Answer

They usually base your due date on the baby's size at the dating ultrasound.

Answer

I would go by ultra sound

Answer

Assuming you had an early ultrasound, before 10-12 weeks I would go based off of that.