Birth Weight Discordance in Very Low Birth Weight Twins: Mortality, Morbidity, and Neurodevelopment

OBJECTIVE: Examine outcomes among birth weight concordant and discordant 401–1500 g twins. STUDY DESIGN: Twins (n=8,114) at NICHD Neonatal Research Network (1994–2011) were studied. Discordance (birth weight difference/larger twin birth weight × 100%) was categorized into: ≤14%, >14–20%, >20–30%, and >30%. Separate logistic regression models for the smaller and larger infants assessed the adjusted association between discordance and outcomes. RESULTS: Compared to the smaller twin with ≤14% discordance, mortality, necrotizing enterocolitis, severe retinopathy of prematurity, bronchopulmonary dysplasia, and neurodevelopmental impairment or death were highest among the smaller twins with discordance >30%. The larger twins with discordance >30% had higher odds of patent ductus arteriosus, moderate-to-severe cerebral palsy, blindness, cognitive and motor scores <70. Odds of cerebral palsy and blindness were also higher among the larger twins with discordance >14–20%. CONCLUSION: Discordance >30% was associated with higher mortality in the smaller twin and higher morbidities among the smaller and larger twins.