dates from scans

I had a scan when I thought baby was 12weeks but they said they reckoned he/she was only 9. They did say they would check again at 20 weeks scan as I really couldn't see how their dates were possible. But is the 20 week scan accurate for dating or is it too late. I know babies come when they want but I'd love to be more confident in the date. Anyone any experience on this?

Hi tilsun, I had an early private scan at 9 weeks and the ultrasonographer mentioned in passing that the most accurate time for dating was before 14-16 weeks, as in, the earlier measurements are more accurate. That said, I'm sure they will still have a reasonable idea at 20 weeks. Maybe someone else can shed some light.

If you are certain of your dates, you are probably right. Not all babies grow at the same rate. On my first pregnancy dd measured at 19-20 weeks when i was in fact 22 weeks. Just like babies develop differently when they are born, they also develop differently in the womb.

Thanks girls, Beaubelle that's what I would have thought oo, was kind of surprised they even mentioned checking at 20 week scan. Redroses the problem is I'm not 100% sure of my dates so I feel like I have to go with theirs, especially as it was so far from my own. Ah well, will just have to stop thinking about it and go with their dates I think.

I would have thought 20 wks was too late but my dates were changed after hospital scan at 22 wks. Also while babies do grow at different rates usually there is a similar consistent growth pattern to babies in the early stages and that's how they can date them more accurately. If you are not too sure of dates then the 20 wk scan will be the one to use however if yu are sure if dates or got a BFP before they say you did, then I'd be looking for another scan earlier.