In case you’re wondering, supertwins are not superheroes. They’re simply “more than twins” or higher-order multiples, including triplets, quadruplets, quintuplets and sometimes even more babies per batch.
Supertwins are not very common, but, like twins, their numbers are increasing with the use of fertility drugs without prescription. Successful supertwin deliveries are also becoming more common because of heightened neonatal care. Fertility technology, including in vitro fertilization and other techniques as well as fertility hormones, is responsible for about half of all supertwins.
Higher-order multiples can be any combination of monozygotic (identical) and dizygotic (fraternal) twins. They can also consist of three or more zygotes. The majority of triplets (66 percent) consist of one pair of monozygotic twins and one singleton. Triplets are about six percent monozygotic triplets and about 28 percent trizygotic (fraternal). Because most multiples derive from more than one egg and sperm combination, triplet incidences vary — like dizygotic twins — according to age, race, hormones and many other factors.
Supertwins are often more difficult to diagnose than twins, because of gymnastic fetal activity in utero. Fetuses can also play a game of hide-and-seek with the sonographer by hiding behind their siblings, making it difficult to get an accurate head count. Doctors may diagnose more or fewer prospective children than are actually in the uterus.
With misdiagnosis of the number of babies and uneventful pregnancies, some mothers have successfully delivered triplets at home without complications. However, advance knowledge of twins and especially of supertwins, often leads practitioners to mandate a hospital delivery. The incidence of cesarean section for the delivery of higher-order multiples is very high in the United States.
As with twins, if you suspect that you are carrying more than two children, make sure you let your doctor know. As soon as you find out, you’ll need to start taking good care of yourself by eating for four (or more) and by getting lots of rest, since your fatigue will often grow right along with your pregnancy load.