Due date changed at 20 week scan

[PennyMordauntsLadyBrain]

Just wondering if anyone could help explain this to me.

I’ve had three scan so far this pregnancy (DC2) - 7.5 weeks were baby was spot on size wise for gestation, then at 10 weeks were he was a few days bigger than gestation. I had my anomaly scan during the week and my due date has been moved forward a week, so instead of being 19 weeks, I’ve skipped to 20 with a revised due date.

Didn’t really get a chance to talk to a midwife about it, and I don’t understand- I thought a foetus grew very predictably in the first few weeks, so the early scan would have the most reliable date?

I know it’s not a massive deal, but I don’t want to readjust my expectations to delivering earlier and then be furious that I’ve gone overdue again!

Are you in the UK? It does sound odd, they adjusted my due date at my 12 week scan, but I was told it wouldn't be adjusted again at any later scan (presumably because growth isn't as predictable after that point).

Yup, I’m in NI!

They said at booking that the “official” due date will be given at my 20 week scan, which I thought was a bit late but it’s my first time in the UK system so I wasn’t sure.

I’m also in NI (went to Mater Hospital)- and also had my due date moved at 20week scam-I think despite what they say unless it’s ivf then it’s not an exact science at all.

Not exact science for sure! Are you an older mum? They get a bit twitchy leaving post 40 weeks if you're older

Nope, I’ve just turned 30 - wonder if it’s something only my hospital do...

@BigBairy I was supposed to have dd at the Mater after moving back to NI at 38 weeks, but had to end up at the Royal. Ulster this time!

Think this might be more a N.I thing rather than England - our dating scans are at 12 weeks and are not adjusted at the 20 week scan. It may be noted if baby is bigger/smaller at that point but they wouldn't adjust due dates - more monitoring for possible growth issues possibly though xx

I'm in NI too and was told I'd be given an exact due date at the 20 week scan! Wonder why it's different here than the rest of the UK? I know they say it isn't an exact science but I do know exactly when I conceived and scans so far have matched up with that (both private and NHS) so if they change my date in 2 weeks time I'll have to tell them it's biologically impossible 😂

I had a scan at 10 weeks and was told I looked to be measuring a week or so bigger, but that it can go a week either way that early, and it would be confirmed at 12 weeks. At 12 weeks, they measured me as 6 days further along than originally thought. So perhaps because your last scan before anomaly was at 10 weeks, baby wasn’t quite big enough for an accurate due date?