Due Date: Dating Ultrasound or LMP?

Question

I had my first ultrasound yesterday and baby is measuring over a week larger than we expected based on the first day of my last period. My OB said we will move the due date up one week for now and will recheck at my anatomy scan to make sure that's still consistent. Has anyone else had their due date moved for the same reason?

Answer

The dating scan is going to be more accurate than LMP. It could change between now and your next one as well.

Answer

My due date was moved from Aug 5th to Aug 12th because my baby is measuring a week behind.

Answer

Going by LMP tends not to be as accurate as you think - not ever woman ovulates in the middle of her cycle and some women hyperovulate. Therefor when the dating scan comes, the baby's due date tends to shift. Of course some babies tend to be bigger or smaller - that's more so in the second trimester as they grow more at their own speed.

Answer

My due date was moved a few days forward from 8/4 to 8/8. I'm happy about that because it gives us more time to be allowed to birth at home (most midwives won't attend homebirth if you are past 41/42 weeks). They look at the size of the fetus. I had a MC in August and when we did have an ultrasound the embryo was measuring several days behind then too. Either my babies are on the small side or I ovulate later than most.

Due Date: Dating Ultrasound or LMP?

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