Do late preterm twins face an increased neonatal morbidity compared with singletons?

Late preterm infants (born between 34 0/7 and 36 6/7 weeks of gestation) have been shown to have a higher morbidity and mortality than term infants. Furthermore, twins, both term and preterm, have a higher neonatal morbidity than singletons. The aim of our study was to examine if late preterm twins consequently have twice the neonatal morbidity when both risk factors prematurity and multiple pregnancy are present.

A retrospective single-centre study was conducted to compare neonatal outcome of late preterm singletons and late preterm twins born between 34 0/7 and 36 6/7 weeks of gestation as well as term twins with a gestational age from 37 0/7 to 41 6/7 weeks. Primary outcome was length of hospitalisation. Secondary outcome was neonatal morbidity.

A total of 845 infants were included. Late preterm twins (n = 243) were hospitalised significantly longer than term twins (n = 107) (13.5 ± 8.0 vs 6.29 ± 2.0 days, p <0.001) and late preterm singletons (n = 495) (13.5 ± 8.0 vs 12.6 ± 8.6 days, p = 0.011). Hyperbilirubinaemia occurred significantly more often in late preterm singletons than in late preterm twins (49.7 vs 29.2%; p<0.001). Otherwise, no significant differences were detected regarding neonatal morbidities or mortality of late preterm singletons and late preterm twins. Late preterm twins had a significantly higher incidence of most morbidities than term twins.

Late preterm twins are hospitalised significantly longer than similar-aged singletons, but have otherwise similar neonatal morbidities. Hyperbilirubinaemia is less frequent in late preterm twins than late preterm singletons.