Neonatal and developmental outcomes of very preterm twins according to the chorionicity and weight discordance.

Perinatal outcomes of twin pregnancies are determined by several factors, such as gestational age (GA), chorionicity, and discordance at birth. This retrospective study aimed to investigate the association of chorionicity and discordance with neonatal and neurodevelopmental outcomes in preterm twin infants from uncomplicated pregnancy. Data of very preterm twin infants who were both live-born between 2014 and 2019 on the chorionicity of the twin, diagnosis of the twin-to-twin syndrome (TTTS), weight discordance at birth, and neonatal and neurodevelopmental outcomes at 24 months of corrected age (CA) were collected. Of the 204 twin infants analyzed, 136 were dichorionic (DC) and 68 were monochorionic (MC), including 15 pairs with TTTS. After adjusting for GA, brain injury, including severe intraventricular hemorrhage and periventricular leukomalacia, was mostly found in the MC with TTTS group, with a higher incidence of cerebral palsy and motor delay at CA 24 months. After excluding TTTS, multivariable analysis showed no association between chorionicity and neonatal and developmental outcomes, whereas small infants among co-twins (adjusted odds ratio (aOR) 3.33, 95% confidence interval 1.03-10.74) and greater discordance (%) of weight at birth (aOR 1.04, 1.00-1.07) were associated with neurodevelopmental impairment. Monochorionicity might not determine adverse outcomes among very preterm twins from uncomplicated pregnancy.