Early dating ultrasound

[cameragirl]

If you had an early dating ultrasound, did the doctor base the EDD off of the sac measurement, or the embyro?

[mom2a4Rashelle]

Typically they get the most accurate measurement early on measuring the lil bean (aka baby)

[MaryLang]

Yup, he measures the babe.

[cameragirl]

My ob's office went with the sac measurement for some reason. That date would have been 3/08/11, and that leaves a conception window of 6/8-6/15, give or take. The sac measured three days behind, so an EDD of 3/11/11. Both dates are possible, especially since I had an odd cycle that month because it was right after a miscarriage.

Not that it matters too much - that gives baby three extra days to decide to come out before they start talking c-section.

[sjdragonfly]

I think they can also base the age on how fast the heartbeat is. I was just reading something about that the other day. I wish I could remember where. Apparently the heart speeds up a certain amount of beats per day in the very beginning so it's pretty accurate if you're having an early enough scan. When I had mine, the little one was 130 bpm, but every time she'd go to measure, the baby would be a bit bigger! Kind of funny. My uterus curves to the back instead of the front so the tech was having a bit of a time getting a good look, I think that's why the measurements kept changing. This also leads me to believe she based the age on the heartbeat instead of the size.