Objective: Approximately one-third of US reproductive-aged women are obese, and prepregnancy obesity is a strong risk factor for adverse fetal and infant outcomes. The annual number of preventable adverse fetal and infant outcomes associated with prepregnancy obesity in the US was estimated.
Design and Methods: Adverse fetal and infant outcomes for which statistically significant associations with prepregnancy obesity had been reported by peer-reviewed meta-analyses, which included fetal deaths and nine different major birth defects, were assessed. The true prevalence of prepregnancy obesity was estimated by multiplying self-reported prepregnancy obesity by a bias factor based on the difference between measured and self-reported obesity in US adult women. A Monte Carlo simulation approach was used to model the attributable fraction and preventable number, accounting for uncertainty in the estimates for:  strength of the association with obesity,  obesity prevalence, and  outcome prevalence.
Results: Eliminating the impact of prepregnancy obesity would potentially prevent the highest numbers of four outcomes: fetal deaths (6,990; uncertainty interval [UI] 4,110-10,080), congenital heart defects (2,850; UI 1,035-5,065), hydrocephalus (490; UI 150-850), and spina bifida (405; UI 305-505). If 10% of women with prepregnancy obesity achieved a healthy weight before pregnancy or otherwise mitigated the impact of obesity, nearly 300 congenital heart defects and 700 fetal deaths per year could potentially be prevented.
Conclusion: This simulation suggests that effective prevention strategies to reduce prepregnancy obesity or the risk associated with obesity could have a measurable impact on infant health in the US.