The impact of maternal body mass index on the phenotype of pre-eclampsia: a prospective cohort study.

OBJECTIVE: We hypothesised that among nulliparous women with pre-eclampsia, overweight or obese women would have a different phenotype of pre-eclampsia compared with normal weight women with pre-eclampsia. Specifically, they are more likely to develop term pre-eclampsia and less likely to have indicators of impaired placental perfusion, e.g. abnormal uterine artery Doppler or a small-for-gestational-age (SGA) infant.
DESIGN: Prospective, multicentre, cohort SCOPE study (n = 3170).
SETTING: New Zealand and Australia. POPULATION: Nulliparous women who developed pre-eclampsia.
METHODS: Participants were interviewed at 14-16 weeks of gestation, uterine artery Doppler studies were performed at 19-21 weeks and pregnancy outcome was tracked prospectively. MAIN OUTCOME MEASURES: Rates of abnormal uterine artery Doppler indices, term/preterm birth and SGA infants were compared between normal, overweight and obese women with pre-eclampsia. Multivariable analysis was performed to examine the association between body mass index (BMI) and term pre-eclampsia.
RESULTS: Of 178 women with pre-eclampsia, one underweight woman was excluded and 66 (37%) were normal weight, 52 (29%) were overweight and 59 (34%) were obese. Pre-eclampsia developed preterm in 26% of women and at term in 74% of women. There were no differences in the rates of term/preterm pre-eclampsia, abnormal uterine artery Doppler indices or SGA infants between BMI groups (P > 0.10). No independent association between BMI and term pre-eclampsia was found (P = 0.56).
CONCLUSIONS: Among women with pre-eclampsia, those who are overweight or obese in early pregnancy are not more likely to have term pre-eclampsia compared with women with a normal BMI. Overweight and obese women require vigilant surveillance for the development of preterm as well as term pre-eclampsia.