Abstract
BACKGROUND: Overweight and obesity greatly increase the risk of preeclampsia. There is a need to better risk-stratify these women in pregnancy and channel resources to those who can benefit most. METHODS: Prospective observational study of 11 962 women with singleton pregnancies attending a routine assessment at 35+0 to 36+6 weeks' gestation at King's College Hospital, London, United Kingdom. Women were categorized by their body mass index at 11 to 13 weeks' gestation as normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), or obese (≥30 kg/m(2)). We recorded maternal demographics, assessed uterine artery pulsatility index and ophthalmic artery peak systolic velocity ratio, and measured carotid-to-femoral pulse-wave velocity. Preeclampsia development was retrieved from medical records. Multivariable logistic regression was undertaken to examine determinants of preeclampsia. Mediation analysis was performed to assess causal relationships. RESULTS: In this cohort, 28.4% were overweight and 17.9% were obese. Preeclampsia developed more often in overweight/obese (versus normal weight) women (6.0% versus 1.7%, respectively; P<0.001); women of Black and South Asian ethnicity were at particularly increased risk (P=0.02 and 0.004, respectively). Determinants of preeclampsia development did not differ by body mass index. Mediation analysis suggested that the effect of overweight/obesity on preeclampsia development may be mediated partly by changes in maternal cardiovascular indices, particularly aortic stiffness (as reflected by carotid-to-femoral pulse-wave velocity, proportion mediated=72.6%). CONCLUSIONS: Risk factors for term preeclampsia are largely similar between overweight/obese and normal-weight women, except for Black and South Asian women, who face a particularly high risk within the overweight/obese group. Maternal vascular assessment may serve as a valuable tool for stratifying the risk for term preeclampsia in these populations.