Arnold Schwarzenegger or Danny DeVito? The fate of twins with necrotizing enterocolitis in the NICU

Previous literature suggests infants of multiple gestation pregnancies have a higher incidence of necrotizing enterocolitis (NEC) than singleton gestations; however, no study has examined the likelihood of co-incident NEC among multiples. We hypothesized an increased incidence of NEC among multiples whose siblings were diagnosed with NEC.

The admissions of infants to neonatal intensive care units were abstracted from the Pediatric Health Information System between 2017 and 2023. Multiple gestational sets were identified by diagnostic code indicating multiple gestation, and matched on hospital center, birthdate, race/ethnicity, and location code. Internal validation of data was performed. The primary outcome was development of NEC.

253,574 NICU infants included, and 8158 (3.2 %, 3982 groupings) were identified to be a part of a multiple set. Multiples had shorter gestations, lower birthweights, and developed NEC more frequently than an uncontrolled cohort of NICU singleton births. However, when controlling for patient demographics multiples were less likely than singleton births to develop NEC (OR 0.77, 95%CI 0.70-0.86). Nevertheless, if one infant in a set developed NEC, a second sibling was more likely to develop NEC compared to the general NICU population (16.4 % vs 2.6 %, p < 0.01). This correlation remained significant when controlling for gestational age, average birthweight of the multiple set, and institutional variation (OR 1.77, 95%CI 1.27-2.48).

Infants born of multiple gestational pregnancies are less likely to develop NEC as compared to a similar cohort of singleton infants. However, if one infant in a multiple set develops NEC, another sibling is significantly more likely to develop NEC.