Vanishing twin syndrome refers to the phenomenon in which a woman diagnosed as carrying twins ends up with a single fetus during the latter stages of pregnancy. The occurrences of this syndrome is a recent phenomenon, and is reported in older women who conceive using in-vitro fertilization methods.
Vanishing twin syndrome is when one of the twins dies early in pregnancy (usually within the first trimester) and is absorbed by the placenta. All this usually happens without the knowledge of the mother. At the most she may experience a light bleeding, but continues with the pregnancy of the surviving fetus.
Even if one of the twins is lost early, it definitely is a loss that is difficult to cope with. Some mothers may feel that it was probably because they slept wrongly or something that they ate which may have caused the loss of one of the twins. However, it is important for all such mothers to know that the baby was lost due to a chromosomal abnormality. The genetic problem in the embryo prevented it from developing into a fetus. Improper placental implantation or some developmental fault that may hinder the development of the major organs could cause the death of the ‘vanishing’ twin.
In many cases, a mother experiencing this syndrome may not have any apparent symptoms. However, she might experience some miscarriage symptoms like vaginal bleeding, cramping, and pelvic discomfort. Also, the hCG levels in the first trimester decline in such cases, where they are expected to rise in twin pregnancies. This may be a reason, although direct relation between both haven’t been conclusively established. However, the bleeding is not as heavy as it is in case of a miscarriage. It is so because the other twin is still there in the womb keeping the hormone levels high, so that the placental lining is not shed. However, there is a small chance that the other baby may also be lost. If this happens, the mother will realize through heavy bleeding, and would be the case of an early miscarriage.
If the twin is lost in the first trimester, there is no threat to the health of the mother or the surviving fetus. The pregnancy continues normally and there are no clinical symptoms, either in the mother or the other twin. However, if the (vanishing) twin dies in the second or third trimester, there are chances that the surviving fetus may suffer from cerebral palsy.
There is a possibility of premature labor, infection due to the death of the other twin, and hemorrhage. In fact, in such a case, there is a threat to the continuation of the pregnancy itself. Although in most cases the vanishing twin is absorbed by its twin, the placenta or the mother’s body, sometimes, the dead fetus may be compressed by the surviving twin. As a result, it may change into a flattened parchment like mass known as the fetus papyraceus. This fetus papyraceus may block the cervix during delivery, and might require a cesarean delivery for the surviving twin.
How Common is Vanishing Twin Syndrome
The first instance was reported as recently as 1945. Since then, this phenomenon seems to be on a rise. However, as more and more studies are being done, it is being realized that this is not a recent occurring. Research indicates that almost 1 out of 8 births start as a twin pregnancy. However, neither the mother nor the doctors ever have the knowledge of the existence of one of the other twins.
With the increase in the availability of ultrasound in early stages of pregnancy, cases of twin pregnancies are easily reported nowadays. In case one of the embryos is lost due to the condition, then this loss is detected and reported in the subsequent ultrasounds. This explains the increased incidence in recent times.
Disclaimer: This HealthHearty article is for informative purposes only, and should not be replaced for the advice of a medical professional.