Postnatal condition of the second twin in respect to mode of delivery, chorionicity and type of fetal growth.

BACKGROUND: The increased use of assisted reproductive techniques (ART) contributes to the increased rate of twin pregnancies, which are burdened with a higher risk of complications. Factors that affect the condition of the second twin are understudied.

OBJECTIVES: The objective of this study was to assess the impact of the delivery mode, chorionicity, amnionicity, and the type of fetal growth on the postnatal condition of the second twin.

MATERIAL AND METHODS: The study included data from 475 pregnant women with twin pregnancies. Maternal age, parity, chorionicity, amnionicity, type of fetal growth, mode of delivery, gestational weeks at delivery, Apgar score, and umbilical arterial blood pH were retrospectively analyzed. Data normality was checked with the Kolmogorov-Smirnov test. The paired Wilcoxon signed-rank test and χ2 test were used for comparisons between groups. To check predictive value of the analyzed variables multiple linear regression was used.

RESULTS: The mean maternal age was 29.22 (standard deviation (SD) ±5.19) years. The maternal age and gestational age at delivery did not differ significantly between women who delivered by cesarean section (CS) and vaginal delivery (VD). In the second twin, the Apgar score and values of arterial umbilical blood pH were lower in infants delivered by VD than in those delivered by CS (6.30 ±2.83 and 7.30 ±0.12; p = 0.0209 and 7.26 ±0.12 and 7.30 ±0.11; p = 0.0236, respectively). In monochorionic diamniotic twins with asymmetric growth, the second twin achieved significantly lower outcome than the first twin. Vaginal delivery was a predictive factor for a lower Apgar score and lower values of umbilical arterial blood pH in second twins, while not in first twins. Symmetrical fetal growth of twins was a predictive factor for better postnatal condition for both twins.

CONCLUSIONS: In twin pregnancies, VD, but not CS, is associated with increased risk of worse postnatal condition of the second twin. In monochorionic diamniotic pregnancies complicated by growth discordance, CS seems to be a reasonable mode of delivery.