My dates say 7+4, scan says 6

[Alexandra84]

Today I’ve been for hospital scan due to needing a precise date for genetic testing. My dates state 7weeks 4 days, but they said around 6 weeks. It was vague. We were busy taking about the genetic testing that I didn’t really grill and ask if the difference in dates was a concern.
They confirmed a heartbeat, and said they didn’t have concerns.
But I wish I’d asked about the difference in dates. Has anyone had this? Did you need an additional scan?

When you say 'your dates' do you mean you know exactly when you ovulated or is that just from LMP?

LMP is a guide only just to give a starting reference point but is based on an average 28 day cycle with ovulation on day 14. It's not accurate for a lot of people.
Your actual gestation goes off date of conception and counts 2 weeks before that so, if your cycles are long/irregular, you ovulate late etc, then that is likely why baby is measuring smaller.

Obviously if you know your dates are definitely correct then that would be more of a worry.

Do bear in mind though that's it's also very hard to get an accurate measurement at 6 weeks as they're working in fractions of millimeters. You normally get invited back around 8 weeks to confirm the dating.

I'm 11+3 now and have had 3 scans. All good so far but I'm about 12 days behind LMP because I ovulated late.

It"s still very early but the fact they saw a heartbeat on your scan and had no concerns is a great sign.

I did and it wasn't a good outcome unfortunately. That said, others will have had similar and had a good outcome. It's just so hard when they scan so early as measurements can be out by a fraction but seem more significant in terms of dates. It s good there was a heartbeat. You'll know more conclusively if you have another scan in 10-14 days. Miscarriage rate drops substantially after 8 weeks but most do occur in weeks 6-8. Hoping things turn out well for you.

Thanks for your response. It was based on last lmp.
To add to the confusion, previous recent cycles have been shorter, sometimes 23/24 days, so I thought if anything they would say I was further ahead than that. In the past they have been bang on 28 days.
I will speak to my midwife tomorrow and see what can be booked in.
Thanks.

Thank you and I’m sorry you had negative news.
could kick myself for not asking the one question that is now playing over in my mind.

I wouldn't worry this soon dates get changed really often. My dates were changed at first scan as baby wasn't measuring the right size but all went well in my pregnancy and baby was born big and healthy. It's really guessing when you may have ovulated based on periods. If your periods have been a bit off then that throws everything off.

If there’s a heartbeat that’s a good sign. The measurements at that stage are so tiny, it’s really hard to be accurate. It’s very common to measure differently to what you think based on last period