Triplet infants with birthweight < or = 1250 grams: how well do they compare with twin and singleton infants at 36 to 48 months of age?

The purpose of this study was to determine if triplet infants with birthweight < or = 1250 g were at increased risk of long-term disability compared with similar birthweight and gestational age singletons and twins. This was a retrospective cohort study of < or = 1250-g infants admitted to a regional neonatal intensive care unit from 1986 to 2001 with follow-up to 36 to 48 months corrected gestational age. Outcomes studied were cognitive ability, cerebral palsy, and neurosensory impairment at 36 to 48 months. Enrollment was 1717 infants: 59 triplets, 402 twins, and 1256 singletons. Triplet infants differed from twin or singleton infants because they were more likely to have older, married mothers (relative risk [RR] 3.62, 95% CI 1.31, 5.94), be products of assisted reproductive technology pregnancies (RR 29.59, 95% CI 13.97, 62.68), be exposed to antenatal steroids (RR 1.55, 95% CI 1.38, 1.75), and were all delivered by cesarean section. Triplet infants had lower risk of having intraventricular hemorrhage (RR 0.19, 95% CI 0.05, 0.75). The risk of cerebral palsy, cognitive delay, total major disability, or chronic lung disease was similar in triplet and twin infants compared with singleton infants. The lower risk of having intraventricular hemorrhage in triplet infants may have been due to the use of antenatal corticosteroids and cesarean section delivery.