Chorionicity and neurodevelopmental outcomes at 5½ years among twins born preterm: the EPIPAGE2 cohort study.

OBJECTIVE:To compare the neurodevelopmental outcomes of preterm twins at 5½ years by chorionicity of pregnancy. DESIGN:Prospective nationwide population-based EPIPAGE2 (Etude Epidémiologique sur les Petits Âges Gestationnels) cohort study. SETTING:A total of 546 maternity units in France, between March and December 2011. POPULATION:A total of 1126 twins eligible for follow-up at 5½ years. METHODS:The association of chorionicity with outcomes was analysed using multivariate regression models. MAIN OUTCOME MEASURES:Survival at 5½ years with or without neurodevelopmental disabilities (comprising cerebral palsy, visual, hearing, cognitive deficiency, behavioural difficulties or developmental coordination disorders) were described and compared by chorionicity. RESULTS:Among the 1126 twins eligible for follow-up at 5½ years, 926 (82.2%) could be evaluated: 228 monochorionic (MC) and 698 dichorionic (DC). Based on chronicity and gestational age of birth, we found no significant differences for severe neonatal morbidity. The rates of moderate/severe neurobehavioral disabilities were similar in infants from DC pregnancies versus infants from MC pregnancies (OR 1.22, 95% CI 0.65-2.28). By gestational age and without twin-twin transfusion syndrome (TTTS), no difference according to chorionicity was found for all neurodevelopmental outcome measures. CONCLUSIONS:The neurodevelopmental outcomes among preterm twins at 5½ years is similar, irrespective of chorionicity.