Risk of severe maternal morbidity in relation to prepregnancy body mass index: Roles of maternal co-morbidities and caesarean birth.

Co-morbidities and caesarean birth explained an association between high prepregnancy BMI and SMM. These findings suggest that promotion of healthy prepregnancy weight, along with management of co-morbidities and support of vaginal birth in pregnant women with high BMI, could reduce the risk of SMM. However, these mediators did not reduce the elevated risk of SMM observed in women with low BMI.