Ultrasound

[ivygrimes]

Heya

When an ultrasound occurs at the 6/7 week IVF scan, besides the fact it is measuring the CRL, I wonder why or how on earth how the machine detects the fetus being 2 weeks ahead?
Gestational pregnancies are 40 weeks and all that but in IVF land, surely it can detect how long the fetus has been growing without a need to add 2 additional weeks on like you would for a natural pregnancy for the LMP way of doing things.

I'd love to know and understand
Thanks

[Tashtash]

Hi from my understanding IVF pregnancies are calculated the same as natural ones because if you go from your LMP week one after you haven’t even conceived (so technically one week pregnant) the second week after is where you have conceived and it is travelling down to the uterus (so technically two weeks pregnant) the third week it implants (so technically three weeks pregnant) so for eg my LMP was 27.9.20 and I had my FET done in the week 3 window which is right because thats when it implanted. Its no different to a natural pregnancy its just weeks 1 and 2 happened in the lab and not my body if you like.

So natural pregnancies still have implantation in week 3 like ivf’ers and if you google it it will explain this. Its not the machine adding two weeks on. For the purpose of your care when you go back into the nhs system they have to work to the same dates so you are booked in for your 12 and 20week scans at the right time and as you know a pregnancy is generally 40weeks long even for those that conceive naturally they will still have only had a bean on board for 38weeks like us. Does that make sense?

Hope that helps but it doesn’t really make much difference as a due date could change anyway when you have your 12 and 20 week scans and they see what baby is measuring.

[ivygrimes]

Thanks for your help explaining this.

Much appreciated.