Calculating due date wrong?!

[futuremummy123]

Hello!

So we are expecting a little one in February! According to my period dates my baby was due around 29th Feb. However, When we went for our 12 week scan she measured us to be 13 weeks, making our due date 22nd February. By this calculation I am now 22 weeks and following my 20 week scan they are saying baby is measuring a week behind… all her measurements put her around the 3rd percentile for 22 weeks, yet when we looked at the 21 week dates bang on the 50th.. is it common that actually baby girl may have been measuring ahead at the 12 week scan and therefore out due date has been estimated incorrectly?

Definitely possible. You’re considered “full term” at 37 weeks and normal to go 2 weeks over due date…that’s a hell of a window! Also remember that measurements from scans aren’t actually that accurate.

My fundal height (measuring bump) was below 3rd centile at 28 weeks. I went for a couple of growth scans and baby actually measured 50th centile. If you're concerned then ask a midwife if you could have growth scans. Mine were accurate but maybe they're not that accurate in earlier and later scans. I've know a couple of women who had regular periods and thought their EDD was incorrect.

I had an exact date as did ivf and based on the scan they would have put me 8 days ahead based on size etc. They actually asked if I was certain of the date.

I know a couple of people who had early babies who were a decent size and they thought dates had been wrong, but as periods were a bit random they were dates based on scans.

According to my scan dates with my first I managed to concieve when DH was in a different country.

I had this with all 3 of mine and went overdue by 2 weeks with all of them and had to be induced with 2 of them. I was sure they'd got it wrong but who knows.

Thank you everyone! I guess it is something I will have to mention at my next appointment. Due to size and placental issues we are already booked in for regular growth scans so I guess everything is in place was just intrigued!