Maternal and Interpregnancy Factors and Risks of First-Time Preeclampsia in Second Pregnancy: A Swedish National Cohort Study.

Abstract

To investigate factors associated with first-time preeclampsia in second pregnancies. Population-based cohort study using Swedish national registers. Sweden 1992-2019. A group of 808 107 women with second singleton deliveries, who did not have preeclampsia in first pregnancy. Information in the Swedish Medical Birth Register, relating to (1) first pregnancy complications, (2) maternal characteristics in early second pregnancy, and (3) interpregnancy changes in risk factor status, was examined for association with first-time preeclampsia occurring in second pregnancy using modified Poisson regression analysis. First-time preeclampsia, and first-time preeclampsia with preterm delivery (< 37 gestational weeks) in second pregnancy. Adjusted relative risks (aRRs; 95% confidence interval) for first-time preeclampsia in second pregnancy increased after first pregnancy complications, including: gestational hypertension (4.61; 4.20, 5.05) and preterm delivery (1.99; 1.87, 2.12). There was a dose-dependent association between interpregnancy weight change and risk of first-time preeclampsia in second pregnancy. Compared to stable weight (BMI -1 to 1 unit) a 2 to 4 BMI unit increase was associated with a 50% increase in risk of first-time preeclampsia (1.57; 1.47, 1.67), and weight loss equivalent to > 2 BMI units was associated with a reduced risk (0.63, 0.55, 0.72). This pattern of association was consistent also when stratifying by first pregnancy BMI (18.5 to < 25, 25 to < 30, 30 or above). In addition to maternal disease and complication in first pregnancy, interpregnancy weight change was also associated with increased risks of first-time preeclampsia in second pregnancy, even in women with normal weight in first pregnancy.