Twin chorionicity and pre-eclampsia

Objective To determine whether the incidence of preeclampsia is different i n dichorionic compared to monochorionic twin pregnancies. Methods The study involved 666 twin pregnancies resulting in two live birth s after 24 weeks of gestation. Ultrasound examination at 10-14 weeks of ges tation demonstrated that 171 (25.7%) were monochorionic and 495 (74.3%) wer e dichorionic twins. Pregnancy outcome information regarding the developmen t of pre-eclampsia was obtained from the maternity units. The incidence of pre-eclampsia in the dichorionic and monochorionic twin pregnancies was com pared. Results The incidence of Pre-eclampsia in monochorionic twin pregnancies (9 .4%) was not significantly different from that in dichorionic pregnancies ( 7.3%) (P = 0.48). Multiple logistic regression revealed that chorionicity h as no effect on the development of pre-eclampsia after adjusting for matern al age, ethnic group, maternal smoking, parity and gestational age at deliv ery (P = 0.6; odds ratio for monochorionic compared with dichorionic twin p regnancies, 1.19; 95% confidence interval, 0.61-2.3). Conclusion In twin pregnancies chorionicity does not affect the incidence o f pre-eclampsia.