Due date calculation

[SMK23]

I had an early pregnancy scan at the hospital. I was predicted to be 9weeks 3days at the time because the date of my last period was 30th July 2024. They started with an ultrasound but mentioned they might not be able to see anything but we could do it vaginally afterwards. They managed to find the baby (everything was good no concerns 😁) but they measured the baby at 11weeks. This would put my conception date around 16th of July 2024, but I had my period on the 30th. How is this possible? If anything I thought maybe I would be 8weeks and not 9weeks. Has anyone had anything similar?

Did you bleed less than usual because it might not have been a proper period? Or maybe the baby looks a lot bigger than average.

Are you sure your period on the 30th was definitely a normal period? Before 12 weeks, the early scan dates can be off and usually way more accurate by the time you have your dating scan, but an almost 2 week ahead measurement does seem surprising, unless it wasn't a proper period that you had on the 30th. I've seen on here before though some women can be so sure of their dates but are measuring ahead or behind with not much explanation and everything works out fine.

11 weeks yesterday would put your conception date to around 2 August not 16 July. Because it's counted from the first day of your last period and very generally women ovulate 2 weeks after that then at conception you're already at 2 weeks.

You could have ovulated on day 3-6 of your period and that 30th could still have been your period.

I am 11+3 today and I ovulated on 31st July (I tracked it). So you could have ovulated around the 3rd August. Even then it could be a day or two later than that if you implanted a bit earlier and because scans are not exact. So you could have just ovulated really early into your cycle eg days 3-6.

Yeah it’s all a bit confusing to me. Because it doesn’t make sense that I’m 11 weeks which would be before my period. It was a regular period, heavily bleeding and wearing tampons. My cycle is short 24-25 days and my period usually only lasts 3 days (third day don’t usually need to wear a pad just liners). My cycle was very regular but i found it hard to track my ovulation, some cycles I detected it and others I didn’t. I probably did ovulate closer to my period than I thought, but still I would have expected to close to the 9 weeks and not 11 weeks. Good to hear the early scans might not be accurate, but the midwife did say she’s seen it where it’s 2-4 weeks off but mostly for people who have irregular cycles. This is all so new to me, and confusing 🫣

If your cycle is 24 days you could ovulate on day ~10, so 8th August which would make you 10+2. So ovulating a day or so early, implantation a bit earlier than typical and the scan can be off by a few days.

That all seams fine to me.

Because it doesn’t make sense that I’m 11 weeks which would be before my period
It wouldn't be before your period. See my lost previously.

Post, not lost. Typo spotted too late to edit.

LMP of 30 July would put conception roughly 10-15 August. Being 11 weeks yesterday puts conception at roughly 3rd August.

Have you been giving your due date? I concieved around 18th July and I am due 10th April.