The influence of hypertensive disorders during pregnancy on the perinatal outcome of different chorionic twins

Objective To investigate the influence of hypertensive disorders of pregnancy (HDP) on the perinatal outcomes in twin pregnancies. Methods This was a retrospective single-center study in which, 2160 twin pregnancies delivered between January 2016 and December 2019 were analyzed, 1661 of which were dichorionic (DC) and 499 monochorionic (MC). The perinatal outcomes were compared in 404 twin pregnancies with HDP, including 157 gestational hypertension (GH), 107 mild pre-eclampsia (MPE), 140 severe pre-eclampsia (SPE), and 1756 twins without hypertensive disorders of pregnancy (no-HDP). Multiple linear regression was performed to analyze the association between perinatal outcome and HDP. Stratified sampling by twin chorionicity (DC and MC) was also conducted. Results There were 330 (19.9%) DC cases complicated with HDP and 74 (14.8%) MC with HDP, and the difference between the two groups was statistically significant (p=.011). After stratification by chorionicity, in the DC twin, there were significantly more deliveries in the GH group, MPE group, and SPE group before 37 weeks than in the no-HDP group (p=.000). Statistically significant differences were found among the four groups in the average small fetus birthweight, the intertwin weight difference, the relative weight discordance, the growth discordance, the incidence of very low birth weight (VLBW), low birth weight (LBW), and the Apgar scores of the small fetus (p<.05). In MC twins, By comparison only on the average gestational age at delivery, the average small fetus birthweight, Apgar scores of large and small fetuses among the four groups, the difference was statistically significant (p<.05). According to multiple linear regression analysis, after controlling for multiple confounding factors, it was found when the degree of HDP in DC twins increased by one grade, the small fetus birthweight decreased by an average of 19.044 g (p=.007), the intertwin weight difference increased by an average of 14.311 g (p=.034), the relative weight discordance increased by an average of 0.6% (p=.013), and the gestational age at delivery decreased by an average of 0.160 weeks (p=.001). Conclusions The perinatal outcomes of different chorionic twins with HDP are different. HDP has a greater impact on the perinatal outcomes of DC twins. The risk of adverse perinatal outcomes in DC twin pregnancy will increase accordingly with each increase in the grade of HDP, but HDP has little or no relevance on the perinatal outcomes of MC twins.

Automated summary

The study found that HDP has an impact on the perinatal outcomes of twin pregnancies, especially more significantly on dichorionic twins, with increasing risk of adverse outcomes with higher HDP grades. However, HDP has little relevance to the perinatal outcomes of monochorionic twins.