The rate of neonatal respiratory distress syndrome/transient tachypnea in the newborn and the amniotic lamellar body count in twin pregnancies compared with singleton pregnancies.

BACKGROUND: Whether or not the period of fetal lung maturity differs between twin and singleton pregnancies has not been clarified. We examined whether or not fetal lung maturity and fetal lung absorption are achieved earlier in twin fetuses than in singleton fetuses.

METHODS: We registered 454 singleton pregnancies and 398 twin pregnancies with no congenital abnormalities affecting the respiratory function or neonatal deaths. All patients were delivered by Caesarean section without labor between 24 and 38 gestational weeks. The amniotic fluid samples were analyzed immediately without centrifugation. A multiple logistic regression analysis was performed to explore the relationship between twin pregnancy and neonatal respiratory distress syndrome and transient tachypnea of the newborn (RDS/TTN).

RESULTS: The rate of RDS/TTN in infants was significantly higher and the lamellar body counts (LBCs) significantly lower in singleton pregnancies than that in twin pregnancies (P < .001). According to a multivariate logistic regression analysis, twin pregnancy (odds ratio, 0.34; 95% confidence interval, 0.22-0.55) was a significant preventive factor for neonatal RDS/TTN.

CONCLUSIONS: We showed that twin fetuses experience more rapid lung maturation and lung fluid absorption than singleton fetuses, as confirmed by the higher LBC values in twin fetuses.