Can due date ever change after 20 week scan?

[rosettesforjill]

I had my 20-week scan yesterday, and all was well except baby measuring small. That means I'm back for a growth scan on 10th January with a consultant. Fine, and will be happy to see the baby again.

However, I heard the sonographer asking who had scanned me at 12 weeks - it was a student - and who was supervising her. At this scan, they had brought my due date forward from 1st May to 22nd April.

I am now concerned that the initial sonographer made a mistake which will lead to increased observation/intervention in my pregnancy and jeopardise my hopes for a home birth - not just because the consultant is involved at this stage, but also because I may be considered "overdue" when in reality I might have an extra week to go. My first was induced for post dates and I am very keen to avoid induction this time round.

If it looks like an error was made at 12 weeks, is it ever possible for the due date to be revised? From the information on the screen yesterday, it looked as if the measurements were about a week behind where I "should" be - putting me back to around 1st May.

Note: I am open to induction/C section/whatever if truly medically necessary and I understand that I can refuse any treatments I don't want. However, for my sanity, I'd prefer not to be getting into arguments with too many people!

Bump 😊

I don't think they change the due date as a result of the 20 week scan as the earlier ones are more accurate in terms of dating. I looked I to this as my partner only qualified for paternity pay by about 5 days so we really didn't want the date to change!

No, in a word. Pregnancies can only be accurately dated early on because by 20 weeks there are significant differences in size between foetuses of the same gestation. You will continue to have the "official" due date you had at the 12 week scan. You can always choose to decline post dates induction if you feel you're not actually post dates.

I've always been told that they adjust the date based on measurements at the 12 week scan, but won't adjust the date again after that.

I was worried about this as I'm pretty certain on my dates but the sonographer at my first scan put my due date forward by about a week. I spoke to a friend who is an experienced midwife and she said you can insist that they don't induce you if you're clear on your dates. They can't do anything without your consent anyway and if the baby is happy in there and there are no medical reasons to be induced then you can just sit tight!

Thanks all. I can't be 100% sure on my dates as we were not trying, not preventing, but given my previous induction experience I will definitely be avoiding it again if at all possible. I think I will raise it with the consultant anyway as I'm not really up for being considered high risk for something that could well be the mistake of an inexperienced sonographer - the supervisor definitely didn't check whether the measurements were being done correctly as she was sitting in the corner going through paperwork!

My due date was changed at my 20 week scan, but I'm in NI where the full set of measurements aren't done at 12 weeks (whole other topic ). I was sure of my dates and I'm still convinced the amended due date was wrong.