Changing national guidelines is not enough: the impact of 1990 IOM recommendations on gestational weight gain among US women

BACKGROUND AND OBJECTIVES: Gestational weight gain (GWG) is associated with both long-and short-term maternal and child health outcomes, particularly obesity. Targeting maternal nutrition through policies is a potentially powerful pathway to influence these outcomes. Yet prior research has often failed to evaluate national policies and guidelines that address maternal and child health. In 1990, the U.S. Institute of Medicine (IOM) released guidelines recommending different GWG thresholds based on women's pre-pregnancy body mass index (BMI), with the goal of improving infant birth weight. In this study, we employ quasi-experimental methods to examine whether the release of the IOM guidelines led to changes in GWG among a diverse and nationally representative sample of women. METHODS: Our sample included female participants of the National Longitudinal Survey of Youth who self-reported GWG for pregnancies during 1979-2000 (n=7442 pregnancies to 4173 women). We compared GWG before and after the guidelines were released using difference-in-differences (DID) and regression discontinuity (RD) analyses. RESULTS: In DID analyses we found no reduction in GWG among overweight/obese women relative to normal/underweight women. Meanwhile, RD analyses demonstrated no changes in GWG by pre-pregnancy BMI for either overweight/obese or normal/underweight women. Results were similar for women regardless of educational attainment, race or parity. CONCLUSIONS: These findings suggest that national guidelines had no effect on weight gain among pregnant women. These results have implications for the implementation of policies targeting maternal and child health via dietary behaviors.