Objective: Obesity has significant implications for the health of pregnant women. However, few studies have quantified its association with maternal mortality or examined the relevant underlying causes and the role of care, although this remains the most severe maternal outcome. Our objectives were to quantify the risk of maternal death by prepregnancy body mass index and to determine whether obesity affected the quality of care of the women who died.
Desing: This is a national population-based case-control study in France. Cases were 364 maternal deaths from the 2007-2012 National Confidential Enquiry. Controls were 14,681 parturients from the nationally representative 2010 perinatal survey. We studied the association between categories of prepregnancy BMI and maternal death by multivariable logistic regression, estimating adjusted odds ratios and 95% confidence intervals, overall and by specific causes of death. Individual case reviews assessed the quality of care provided to the women who died, by obesity status.
Results: Compared with women with normal BMI, underweight women (<18.5 kg/m2) had an adjusted OR of death of 0.75 (95% CI, 0.42-1.33), overweight women (25-29.9 kg/m2) 1.65 (95% CI, 1.24-2.19), women with class 1 obesity (30-34.9 kg/m2) 2.22 (95% CI, 1.55-3.19) and those with class 2-3 obesity (≥35 kg/m2) 3.40 (95% CI, 2.17-5.33). Analysis by cause showed significant excess risk of maternal death due to cardiovascular diseases, venous thromboembolism, hypertensive complications and stroke in women with obesity. Suboptimal care was as frequent among women with (35/62, 57%) as without obesity (136/244, 56%), but this inadequate management was directly related to obesity among 14/35 (40%) obese women with suboptimal care. Several opportunities for improvement were identified.
Conclusions: The risk of maternal death increases with BMI; it multiplied by 1.6 in overweight women and more than tripled in pregnant women with severe obesity. Training clinicians in the specificities of care for pregnant women with obesity could improve their outcomes.