EDD

Ok so I’m going to try and make this make sense haha I am 34 weeks pregnant. We found out quite late at 12 weeks as I had no signs. We were quite an active couple so had sex regularly weekly so est conception date was impossible when we found out I was pregnant. I was also on the contraceptive pill so did not have periods ! The midwife used the size of baby to est due date hence why I am now ‘34 weeks’ But what if when I went for that first appointment I was actually 20 weeks but baby was small so they guessed baby was 12 weeks and that’s what they’re going off. Does that make sense? So becauce my EDD is based on size how do they know that i was not actually 20 weeks when I went in but baby is just small - does that makes sense? Haha

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What coincides with your last period?

Sorry forgot to add - I was also on the pill so had no had a period for over a year …!

Are you in a position to go for a private scan? I’m guessing you’re based in the UK being on this group, not sure where abouts but some ultrasound places are like £45-£60. Nice to get some extra piccies of baby but then they’ll also say sizes too if it ties in. I think if your fundal height is about right for your weeks then I think they should have it as close as possible xx

That’s a tricky one then. They must be able to tell from how developed they are I expect? I would think different organs are more clear at different times x

I think everyone is dated by size at that point rather than cycle dates. That’s why you get put forward or back a couple of days based on their measurements!

EDD from scans isn’t just based off of their weight but also head circumference, femur length etc and it’s also based off of their development. For instance at 12 weeks they’d only see a nub but by 14 weeks they’d see actual genitalia. If they couldn’t see their genitalia they’d know baby was below 14 weeks and loads of other things too.

They measure a lot of things during the scan and are also only able to pick up and identify certain things when baby is a certain amount of weeks. The date they gave is likely to be accurate five or take or few days xx

The estimation from the scan is more than just size, also developmental features. They'd have noticed at the 20 week also if things didn't look right for the gestation. They're never going to be 100% accurate, but I imagine they won't be far off!

A 20 week baby would not be the size of a 12 week one. At 12 weeks baby’s are usually around the same size and follow a similar growth pattern, which is why they can say you’re “12+ so many days” by measuring the crown to rump length, it is still an approximation though; but a pretty accurate one. At 12 weeks the organs can’t be accurately assessed and they aren’t developed enough to assess either. As your pregnancy progresses, genetics and sometimes complexities can create growth differences, which is why babies differ in size and weight at birth.

When I had a 20 week scan with the consultant he said all babies are basically the same size until then and after they they will be bigger or smaller. So everyone's edd is based off measurements at the end of the day and not your last period so it should be accurate from your first scan, don't worry! X

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