Do twins mature earlier than singletons? Results from a matched cohort study

OBJECTIVE: Our purpose was to determine whether, as a consequence of advanced maturity, preterm twin infants have a more favorable neonatal outcome than matched singleton infants. STUDY DESIGN: A matched cohort study design was used. Two hundred twenty-four twin infants (112 sets) were matched for gestational age, race, gender, and mode of delivery with singleton infants who were delivered because of refractory preterm labor. Pregnancies with maternal medical disease including preeclampsia, premature rupture of membranes, twin-twin transfusion syndrome, and known fetal anomalies were excluded. Information was obtained by review of maternal and neonatal charts. RESULTS: There was no difference in the incidence of neonatal death (5% vs 7%, p = 0.66), respiratory distress syndrome (38% vs 35%, p = 0.54), grades 3 and 4 intraventricular hemorrhage (5% vs 4%, p = 0.63), grades 2 and 3 necrotizing enterocolitis (4% vs 6%, p = 0.52), and 5-minute Apgar score less than or equal to 6 (21% vs 21%, p = 1.00). Twins had a higher incidence of admission to the Special Care Unit (88% vs 72%, p <0.001). Results were similar when analysis was limited to presenting twins, nonpresenting twins, and twins concordant with controls for antenatal glucocorticoid exposure. CONCLUSION: Twin infants do not have accelerated maturation and improved neonatal outcome compared with matched singleton infants born at the same gestational age because of preterm labor.