Worried, 12 Week Scan Baby Measured 1 Week Behind

[YellowP]

Hi, at my 12 week scan, the Midwife explained that our baby was measuring 10 weeks rather than 11 weeks, by going of the first day of my last period I should have been 11 weeks, and because there is a 7 day difference (10 weeks vs 11 weeks) a consultant would have to rescan to confirm measurements and due date. The MW measured, CRL 3.37cm, I asked is everything ok and she said they are just so curled up and if they stretched out it would make a difference to their measurement. She seemed so happy with everything and pointed and their round head, said there was plenty of fluid around the baby, she even pointed at their eyes, nose, and said “oh look they are rubbing their little face” and there was a beautiful heartbeat but still I can’t help but be so worried - and I’m constantly asking myself: are they ok? Are they growing? This is our little rainbow baby, and given our previous loss it is only adding to my worry too - will our baby make it? Thanks for any advice or shared experience.

You probably just ovulated later in your cycle. Going off LMP is not always accurate.

@DaisyChain16 maybe so, but because of our loss I was tracking and anticipating my fertility window, and while we tried to time the magic as close to ovulation day, maybe the ‘real’ magic took a little longer?

@YellowP did you use opk and/or bbt to measure ovulation?

My ovulation occurred on day 24, which is 10 days later than a typical cycle. So straight away when they ask for my lmp I say it but then say ‘my ovulation was x, therefore I’d put my Lmp at y instead’. I would be 10 days behind if I went off my lmp.

@Blue2020 thank you so so much - I never thought about it this way and given our loss, which happened in June, and we fell pregnant in July, which probably has meant things aren’t exactly accurate by going of LMP (I hope any way 🤞🏻) thank you again, some slight relief.

My first I was moved back 6 days, and my current pregnancy I was moved back 1.5 weeks. I have longer cycles than normal so ovulate between day 20-25.

Its really common for dates to shift at the 12 week scan, and a week shift is within the realms of normal. It’s going on length and they’re not all going to be the exact same size, plus 3 different sonographers could all measure a millimetre or so different which will impact it. DS measured 5 days ahead of my dates at 12 weeks but I was also tracking and I know when he was conceived. I’m sure it’s fine!

5 days behind*

@Hatscats congratulations on your pregnancy. With my first I didn’t experience this and I suppose that’s also why I’m worrying because I’m comparing and I know I shouldn't. Thanks for sharing, again that helps me to worry a little less - when these things happen you believe it’s only happening to you and so it must mean something is wrong but to hear someone else has experienced the same and all is ok and has been ok makes it so much easier - thank you again

@BuffaloCauliflower thank you 😘

This pregnancy I'm 12 days behind my period dates, and I have regular 28 day cycles and got a positive test the day my period was due.

No idea how it happened but due this month and all fine!

@addler thank you so much for sharing, that has put my worries to ease a little for sure. Good luck with your new little arrival ❤️

Hi, wondering if you have an update. I'm currently 13 weeks but only measured 12w2d so baby is behind

Are you going off your LMP? I tracked ovulation and by my dates I'm 8 weeks and 5 days. However, NHS has put me at 9 weeks and 1 day based on LMP but my cycles are longer so I fully expect when I have my scan which is at 12+4 (NHS dates) they'll put me back to closer to 12 which will be in line with ovulation. I know it's hard but I wouldn't worry about only a few days.

@jellyfish2 hi, i had fertility treatment so my dating is exact .
I've have 2 previous scans also and the gestation dates matched up. Baby just dosent seem to have grown much in the past week

I was a week behind at my 12 week scan so had to go back the next week. Not sure why, maybe I implanted late but anyways little one is nearly 2 now so doing great.

@MoonstoneAndRoseQuartz hi hun. Have u got an update? Same thing happenes to me now. I’m also IVF pregnancy and today’s scan measuring me 6days behind. Meant to be 14w4d and measuring 13w6d. I also had lots of previous scans and it’s first time that we have a gap I was always measuring spot on.

@CB2805 I have a scan booked for next week.
🤞 I'm just hoping baby has had a growth spurt.
The scariest thing is no one tells you whether it's normal or not when they measure behind. Obviously it's hard not to be concerned

@MoonstoneAndRoseQuartz i hope everything turns out well🤞but OB reassured me that’s nothing to worry about but can’t help it. Keep me posted🫶🏻

@CB2805 I will do.
I was scanned today again , although they didn't measure baby but at least baby is doing ok with heart beating so I've found that reassuring at least

@MoonstoneAndRoseQuartz thats great to hear🫶🏻 just had my first consultant appointment today due to twins and I mentioned the measurements. She start laughing tbh😅 she mentioned she had lots of patients mention at this point that measurements in private scans are off. She said that it’s nothing to worry about and that thats one of the reasons dating scans happened until 12w mark. Anyway i really hope she’s right for both of us🤞🤞 can’t wait for my next scan now!

This exact thing is happening to me right now. Do you have any updates? Xx

Ultrasound scans have around a one week margin of error anyway. So you might be correct on your dates and it would still be fine, just growing a baby on the smaller side which is completely fine and normal. Not all babies can be bigger than average after all, that's what averages are for.

I'm pregnant with my third and they moved my EDD back a full 7 days this time too. My baby is looking to be on the smaller side I think but my first was as well.

This thread is from two years ago, not sure if you'll get an answer now

@BabySisComing yes my bubbas are a thriving 5month olds now! The bigger they were getting the more inaccurate measurements I was getting especially after the 12w mark. It’s all down how skilled the sonographers are, positioning of baby etc.
easy to say but don’t stress much unless there is actually something off, I wish I had enjoyed more my pregnancy rather than worry about every little thing🫶🏻