Vanishing Twin Syndrome and possible complications

Dear Prof. Winston,

I had ICSI treatment in June – two embryos were put in and at 6wk4d, a viability scan showed two sacs and two heartbeats, although one sac was much smaller than the other, and I was told I had a viable twin pregnancy. At 10wk2d, I had a private scan and was told that one twin had died – only a yolk sac could be seen.

I have just been for my 12wk scan today and a consultant said that due to Vanishing Twin Syndrome there was a 10% chance of the remaining baby having some kind of problem, as there was no way of knowing if the twins had been identical or if they had been sharing a placenta, even though two embryos were put in and there were two sacs. This was a shock to me as online info I read about VTS after the 10wk scan suggests the early loss of a twin is not a problem for the remaining twin.

Can you clarify this for me?

Thank you


Dear L.,

It is extremely common for a twin to disappear leaving its sibling perfectly untouched.  It is only since ultrasound has been widely used for very early pregnancy screening that we have found that many humans have twin pregnancies but that one twin disappears soon after conception.  Yes, there may be a very small chance of a problem with your remaining baby but this is genuinely unlikely.  I would not worry and I expect future scans will reassure you.

Best wishes,

Robert Winston