Re: What is "Vanishing Twin Syndrome"? I'm having twins, is this something I should worry about?
In some cases, one fetus in a multiple pregnancy will die in the womb, and the fetal tissue will be condensed in its sac by the other twin, placenta, or mother, giving the appearance that the baby has literally disappeared. This is what we call Vanishing Twin Syndrome (VTS). VTS usually occurs in the first trimester, and rarely are there real medical risks to either mom or the other twin that are associated with it when it does happen this early on.