Maternal obesity and severe pre-eclampsia among immigrant women: a mediation analysis

We investigated the extent to which pre-pregnancy obesity mediates the association between maternal place of birth and severe pre-eclampsia in the PreCARE cohort of pregnant women in Paris (n = 9,579). Adjusted path analysis logistic regression models were used to assess the role of pre-pregnancy obesity as a mediator in the association between maternal place of birth and the development of severe pre-eclampsia. We calculated 1. adjusted odds ratios and 95% confidence intervals for the total exposure-outcome association and for the direct and indirect/obesity-mediated components 2. the indirect/obesity-mediated effect. Ninety-five (0.99%) women developed severe pre-eclampsia, 47.6% were non-European immigrants, 16.3% were born in Sub-Saharan Africa, and 12.6% were obese (BMI > = 30 kg/m²). Women experiencing severe pre-eclampsia were more likely to be from Sub-Saharan Africa (p = 0.023) and be obese (p = 0.048). Mothers from Sub-Saharan Africa had an increased risk of severe pre-eclampsia compared to European-born mothers (aOR 2.53, 95% CI 1.39-4.58) and the obesity-mediated indirect effect was 18% of the total risk (aOR 1.18, 95%CI 1.03-1.35). In conclusion, Sub-Saharan African immigrant women have a two-fold higher risk of developing severe pre-eclampsia as compared to European-born women, one-fifth of which is mediated by pre-pregnancy obesity. Our results quantify the potential benefit of decreasing obesity among at-risk women.