Prepregnancy BMI and Gestational Weight Gain

The 2009 National Academies report, Weight Gain During Pregnancy: Reexamining the Guidelines, concluded that there was insufficient evidence to support weight gain recommendations for women in higher classes of obesity or those who are underweight. Since that time, the prevalence of obesity among women of reproductive age has continued to rise. Both obesity and gaining excess weight during pregnancy may exacerbate the potential for adverse outcomes during the perinatal period.

In September 2025, the National Academies convened a workshop to address issues related to gestational weight gain (GWG) and explore whether there is evidence to support updating the 2009 recommendations. Speakers explored topics including emerging evidence on health outcomes related to prepregnancy weight and GWG, the role of dietary patterns in GWG and pregnancy-related outcomes, and the relationship of social and economic characteristics to prepregnancy BMI and GWG. This Proceedings of a Workshop summarizes presentations and discussions that took place during the event.