Risk factors for preeclampsia in twin pregnancies: a population-based matched case-control study

To evaluate associated factors for preeclampsia in twin gestations and to compare incidences of pregnancy complications among twin pregnancies with vs. without preeclampsia.

We performed a case-control study using a population dataset of twin pregnancies delivered after 24 weeks of gestation, in Slovenia, between 1997 and 2009. Cases were twin gestations complicated by preeclampsia and controls were cases matched by gestational age, parity, and chorionicity.

We identified 181 cases (4.7%) of preeclampsia among 3885 twins and 542 matched controls. High pre-pregnancy body mass index (BMI) and gestational diabetes were significantly associated with preeclampsia [odds ratio (OR) 1.8, 95% CI 1.26, 2.77 for overweight (BMI 25.0-29.9); OR 4.72, 95% CI 2.83, 7.89 for obese (BMI≥30), and OR 2.19, 95% CI 1.03, 4.68 for gestational diabetes]. The association was not significant for preexisting hypertension, maternal age, smoking, and pregnancy following assisted reproduction. Placental complications (previa, abruption, or adherent placenta) were more common, and low birth weight less common in the preeclampsia group (P=0.03 and P=0.01, respectively).

High pre-pregnancy BMI carries an especially high risk for the development of preeclampsia and its complications in twin gestation.