To be born twin: effects on long-term neurodevelopment of very preterm infants-a cohort study

ObjectiveTo examine the effect of twin birth on long-term neurodevelopmental outcomes in a cohort of Italian preterm infants with very low birth weight. Study designWe performed a retrospective cohort study on children born in a tertiary care centre. We included children born between 1 January 2007 and 31 December 2013 with a gestational age (GA) of & LE;32 weeks and birth weight of <1,500 g. The infants born from twin pregnancies complicated by twin-to-twin transfusion syndrome and from higher-order multiple pregnancies were excluded. The children were evaluated both at 2 years corrected age and 5 years chronological age with Griffiths mental development scales revised (GMDS-R). The linear mixed effects models were used to study the effect of being a twin vs. being a singleton on GMDS-R scores, adjusting for GA, being born small for gestational age, sex, length of NICU stay, socio-economic status, and comorbidity score (CS) calculated as the sum of the weights associated with each of the major morbidities of the infants. ResultsA total of 301 children were included in the study, of which 189 (62.8%) were singletons and 112 (37.2%) were twins; 23 out of 112 twins were monochorionic (MC). No statistically significant differences were observed between twins and singletons in terms of mean general quotient and subscales at both 2 and 5 years. No effect of chorionicity was found when comparing scores of MC and dichorionic twins vs. singletons; however, after adjusting for the CS, the MC twins showed lower scores in the hearing and language and performance subscales at 5 years. ConclusionOverall, in our cohort of children born very preterm, twin infants were not at higher risk of neurodevelopmental impairment compared with singletons at pre-school age.