IVF- please help, anxious blighted ovum

[Nparchie]

I had a FET on 13th June of a 5 day blast. I was told on embryo transfer day that I would be 2 weeks 5 days pregnant so I’ve been basing my dates off that ever since.

last Friday (4w6d) I got some light spotting that lasted a few hours, so the following Monday (5+2) and Wednesday (5+4) I had HCG levels tested to make sure they were still rising appropriately. They were 6303 and 11,595 respectively (clinic was happy with this). I also had no more bleeding all week…

until Friday (5w6d) I had more light bleeding. Clinic advised me to go for scan which showed I was measuring c5 & a half weeks ( a few days behind) and they could see sac and yolk but no Fetal pole. The Sonographer wasn’t worried and said this was totally normal for 5 and a half weeks. They also found a small SCH which explained the cause of bleeding.

I guess my question is, with IVF pregnancies is the clinic dating guidelines 100% correct or does it depend on when implantation actually happened?

I’m feeling incredibly anxious about lack of Fetal pole based on what I thought the dates were (5+6) and worried it will be a blighted ovum?! but then based on ultrasound measuring dates then it would explain why only a yolk could be seen at this point.

Has anyone else experienced this & how did it turn out? Super nervous especially as my first transfer failed to implant at all x

I had something similar. Baby was a week ‘behind’ where she should have been all the way through pregnancy. She was fine. Hang on in there!

Ultrasound dates can vary from IVF dates. Have you got another scan booked in? Know it will be an anxious wait - hope all is well with your pregnancy. NHS maternity normally use ultrasound dates which is always a strange one after fertility treatment when people know exactly how pregnant they are!

Don't worry, this happens ALL the time. There's a number of reasons for this:

1. At this stage the difference between a 5w6 pregnancy and a 5w3 pregnancy is a millimeter or so - it's virtually impossible on an ultrasound to get a completely accurate measure as your talking about something so tiny and ultrasound just aren't quite that precise.
2. Yes implantation happening a little bit earlier or later can make a difference at this stage to the size
3. Babies vary significantly size wise when they are born - anything from about 5.5lb to 12lb is normal - just consider that the largest of those babies are more than twice as big as the smallest at 9 months! , at this early stage the difference are minimal but they are already at play

Congratulations on your pregnancy, try to enjoy ❤

It’s very normal for the embryo to measure a few days out when it’s so early. It’s absolutely tiny so it’s difficult to measure, and the measurements are based on averages so there’s going to be variation. My embryo was measuring around 3-4 days behind at my 7 week scan, had caught up by the 12 week scan, and now I’m 38 weeks they’re measuring above the 95th centile.

In my experience the due date isn’t changed from what the clinic says based on transfer date, but it seems to vary by location as some people have their date amended at the 12 week scan.

Thanks everyone for your messages, that’s a bit more reassuring. For those of you that were measuring behind, did you go for an early scan and did that impact what you saw on the ultrasound (like the Fetal pole in my case?)
ever since Friday I feel like I’ve fallen down the google rabbit hole reading about all the worst possible outcomes - why do we do this to ourselves?

My 5 week scan was behind, and baby never caught up with where she should be, but staying growing about a week behind throughout