New study examines Vanishing Twin Syndrome

Find out how Vanishing Twin Syndrome impacts the outcome of a pregnancy. A vanishing twin is defined as a first-trimester loss of one twin.

By Kate Phillipa Clark

A recent study from Japan examines how Vanishing Twin Syndrome impacts pregnancies. Vanishing Twin Syndrome is when a twin disappears during pregnancy as a result of a miscarriage.*
Obstetric and neonatal outcomes of 130 births were examined. Three groups were formed. One group with singleton pregnancies, one with twin deliveries and one with pregnancies diagnosed with a vanishing twin. The losses were detected by ultrasound. All pregnancies were achieved after assisted reproduction.

*Unlike other miscarriages, there are generally no signs of Vanishing Twin Syndrome. The miscarried twin or multiple dies in the womb and is partially or completely reabsorbed by the mother or other twin.

Outcome was better in the vanishing twin group

There were 96 singleton pregnancies, 10 cases of Vanishing Twin Syndrome, and 24 twin deliveries. The obstetric and neonatal outcomes were compared. They were quite similar between the vanishing twin group and singleton group, although there was a trend towards an increased rate of preterm delivery, extremely preterm delivery, and low birth weight in the vanishing twin group. Nevertheless, outcomes were significantly better in the vanishing twin group than in the twin group. The rate of preterm delivery was significantly higher in the twin group than in the vanishing twin group. Furthermore, birth weight was significantly lower in the twin group than in the vanishing twin group, and the rate of low birth weight was higher in the twin group than in the vanishing twin group.

Trend towards an increased rate of preterm delivery

The researchers concluded that obstetric and neonatal outcome after assisted reproduction may deteriorate according to pregnancy status in the following order: singleton, vanishing twin and twin pregnancy. The obstetric and neonatal outcomes were similar between the vanishing twin group and singleton group, although there was a trend toward an increased rate of preterm delivery and low birth weight in the vanishing twin group.

About the Author

Kate Phillipa Clark

Kate Phillipa Clark has a bachelor in Journalism and an Executive Master in Corporate Communication. She is an identical twin and so is her father.