Risk factors for preeclampsia in Japanese twin pregnancies: comparison with those in singleton pregnancies

To identify the factors associated with the increased risk of developing preeclampsia in twin pregnancies compared with those in singleton pregnancies.

We reviewed the obstetric records of all deliveries at > or =22 weeks' gestation managed at the Japanese Red Cross Katsushika Maternity Hospital between 2001 and 2007.

The incidence of preeclampsia in the twin pregnancies (7.6%: 45 in 593) was significantly higher than that in the singleton pregnancies (1.7%: 196 in 11,311; P < 0.01). In singleton pregnancies, the developing preeclampsia was associated with maternal age at > or =35 years, primiparity, maternal BMI > or =25 before pregnancy, history of infertility therapies such as IVF and having a history of previous preeclampsia. In twin pregnancies, however, the developing preeclampsia was not associated with these variables.

In Japanese women, the factors reported to be associated with the increased risk of preeclampsia in singleton pregnancies may not alter the increased risk of preeclampsia in twin pregnancies.