Monochorionic Twins Measuring Behind

[Ara26]

Hi everyone,
I’m looking for some reassurance or to hear from anyone who has been through something similar.
I’m currently 6 weeks and 5 days pregnant following IVF, and I’m carrying monochorionic twins (both in one sac). Both babies have strong heartbeats, which I’m incredibly grateful for.
What I’m struggling with is that the measurements seem to be conflicting between scans. Last week in EPU (at around 6 weeks 1 day), one twin measured 5.5 mm (around 6+1) and the other measured 2.4 mm. I had another scan today with my fertility clinic, and now both babies are measuring almost the same size at around 4.3–4.6 mm, which corresponds to about 5 weeks 6 days. So instead of one staying ahead, they now both appear to be measuring around 6 days behind where I thought I should be.

I’m finding it difficult to understand how one baby could appear to measure smaller than it did a week earlier.
Has anyone had early scans where the measurements seemed to go backwards or varied between scans, but everything turned out okay? Did your babies catch up at later scans?
I’m trying to stay positive because the heartbeats are reassuring, but after previous pregnancy loss I’m finding the uncertainty really difficult.
I’d really appreciate hearing about anyone’s experiences. Thank you so much for reading.

I'm really no expert but have read on here before that when the measurements are so close (1mm or less) in these early scans, they just cant be as accurate. It looks like youre tlking a different of maximum 1.1mm which could come down to how the sonogrpher was trained, how the babies were positioned etc and the fact that the measurements who kne baby jas shrunk just shows how inaccurate the measurements are really - that wouldn't happen. When's your next appointment?

Sorry for the typos - I got a phone call as I finished typing and clearly didn't proof read! Hopefully someone more in the know will come by soon with some helpful information.

I do appreciate it’s worrisome but its really down to positioning and the sonographer. I had MCDA twins where they shared a placenta but had their own sacs. The early scan (first done at 9 weeks) showed one twin much smaller, evened out got 12 weeks, scanned fortnightly thereafter due to concerns about twin to twin transfusion syndrome. One twin constantly measured behind (by over a lb by time we were getting to delivery date) however there was only 6 ounces between them when born.

I think it’s best to consider scans as educated guesstimates rather than definitive when it comes to measurements.

Thank you. My next appointment will be my booking appointment with maternity next week Wednesday. Thinking about booking a private scan next week Monday to see if there has been any growth.

My scan last week at the EPU gaveu me a bit more reassurance as at least one was measuring “on track” now both are considered behind. I know it’s still early days and these measurements can be off by the slightest movement.
My consultant scanned me today - she wasn’t overly optimistic, but I was still discharged from the ivf clinic.

I’m just deflated, years of ttc, loss and heartache, to finally see a positive pregnancy test and just have this hope that I would end up with a healthy baby to then find out the embryo split (1% chance of it happening) and having a high risk twin pregnancy that could go either way is just another heartbreak 😔