What is Vanishing Twin Syndrome?

You’ve just had your first ultrasound and everything looks healthy. In fact, you saw two heartbeats. Twins! You’re pretty excited, and your intended parents are over the moon. But, everyone is telling you not to get too excited just yet. Why? Many pregnancies that appear as twins or more at the six-week mark may appear as a singleton gestation by the end of the first trimester. More often than not, the reason for this is a condition known as vanishing twin syndrome (VTS).

Vanishing twin syndrome, first discovered and researched in 1945, happens when one or more fetuses in a multiple fetus gestation miscarries while at least one other fetus continues to grow and thrive. The surrogate’s body, the other fetus or the placenta absorbs the tissue of the other twin, causing the visual effect of a “vanishing twin.” Since most cases seem to be linked to chromosomal abnormalities, this syndrome tends to impact fraternal (or non-identical) twins on a far larger scale than identical twins.

The immediate concern of most intended parents in this situation is: “What does this mean for the remaining fetus?” Typically, when VTS occurs within the first 13 weeks of gestation, there are limited to no negative implications on the remaining twin or the surrogate. While highly unlikely, VTS can still occur in subsequent trimesters. In these cases, there have been links between the surviving twin and an increased risk of developing cerebral palsy. However, the rates of losing a twin to VTS or other causes tends to decrease considerably around the close of the first trimester. The end of the first trimester is also when singleton miscarriages begin to decrease.

How is Vanishing Twin Syndrome identified?

Symptoms usually begin early in the first trimester and include bleeding, uterine cramps, and pelvic pain. While some carriers may experience miscarriage symptoms to signify that a twin has died, many will not exhibit typical signs. There will simply be one less heartbeat at the next ultrasound.

What is the Cause?

The first thing you need to understand about VTS is that it’s no one’s fault. This is not the result of something a surrogate did or did not do, and it’s not the fault of an improper medical dosage or administration. Researchers believe that improper umbilical cord implantation or abnormal chromosomal composition may play a role in VTS.

Statistics & Case Study

According to the American Pregnancy Association, VTS isn’t uncommon early in multi-fetus gestations. In fact, the organization estimates that somewhere between 21-30% of multi-gestation pregnancies will result in VTS. This is not a new condition or one that is occurring more often than in previous generations. Modern science has allowed us to see the syndrome more easily now. In previous generations, the carrier would simply have never known that a second fetus existed, but earlier and better sonography makes it possible to detect that second heartbeat before it has vanished.

While it’s exciting to get news that you have been confirmed with twins, try to remain calm and cautious over the next six weeks or so as doctors keep a close eye on all developing fetuses.

As you wait, browse through Growing Generations’ online resources for surrogates to find common cures for morning sickness, tips on how to cope with round ligament pain, and more.