Maternal obesity and infant mortality: a meta-analysis.

BACKGROUND AND OBJECTIVES Despite numerous studies reporting an elevated risk of infant mortality among women who are obese, the magnitude of the association is unclear. A systematic review and meta-analysis was undertaken to assess the association between maternal overweight or obesity and infant mortality. METHODS Four health care databases and gray literature sources were searched and screened against the protocol eligibility criteria. Observational studies reporting on the relationship between maternal overweight and obesity and infant mortality were included. Data extraction and risk of bias assessments were performed. RESULTS Twenty-four records were included from 783 screened. Obese mothers (BMI ≥30) had greater odds of having an infant death (odds ratio 1.42; 95% confidence interval, 1.24-1.63; P < .001; 11 studies); these odds were greatest for the most obese (BMI >35) (odds ratio 2.03; 95% confidence interval, 1.61-2.56; P < .001; 3 studies). CONCLUSIONS Our results suggest that the odds of having an infant death are greater for obese mothers and that this risk may increase with greater maternal BMI or weight; however, residual confounding may explain these findings. Given the rising prevalence of maternal obesity, additional high-quality epidemiologic studies to elucidate the actual influence of elevated maternal mass or weight on infant mortality are needed. If a causal link is determined and the biological basis explained, public health strategies to address the issue of maternal obesity will be needed.