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Multiple births

When do you start showing with twins? What is life with twins like? Join the conversation on our Multiple Births forum.

IVF Monochorionic Twins Measuring Behind

1 reply

Ara26 · 03/08/2026 16:47

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 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.

OP posts:
ExplodingSmittens · 04/08/2026 06:08

I don’t have any experience sorry but hopefully this will bump for you and someone will be along soon who knows more Flowers

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