Hypertensive disorders in twin pregnancy

Objective: To compare the incidence and severity of pregnancy-induced hypertensive disorders in twin pregnancy and in singleton gestation. Study design: Case-control study in the setting of a University HOspital. Each pregnancy of a consecutive series of 187 twin pregnancies attending the antenatal clinic and booked before a gestational age of 24 weeks was matched for maternal age, parity, and gestational age at delivery with a singleton pregnancy delivered in the same year. Primary end points of the analysis of the course and outcome of pregnancy were pregnancy-induced hypertension and proteinuric pre-eclampsia. Results: In the twin pregnancy group, 21% of patients met the criteria for the diagnosis of a pregnancy-induced hypertensive disorder, compared with 13% in the singleton pregnancy group (P < 0.05). The difference was due to a significantly higher incidence of pregnancy-induced hypertension in twin (15%) than in singleton (6%) pregnancy (P < 0.05), in particular in nulliparous women. The incidence of preeclampsia was similar in twin (6%) and singleton pregnancies (6.5%), without a difference in severity and in the occurrence of the HELLP syndrome. Conclusion: The incidence of non-proteinuric pregnancy-induced hypertension, but not of proteinuric preeclampsia, is increased in twin pregnancy.