Trends in Gestational Weight Gain From 2007 to 2019: A Prospective Cohort Study

Gestational weight gain (GWG), the maternal weight gained between pre-pregnancy and delivery, is an important risk factor for adverse maternal and infant health outcomes. In 1990, the National Academy of Medicine released GWG recommendations based on pre-pregnancy body mass index (BMI). These guidelines were revised in 2009, yet few studies have assessed temporal trends in GWG following the change.

To evaluate temporal trends in total GWG within a large, ongoing pregnancy cohort.

We used data from a prospective cohort in Boston, Massachusetts, of 3675 participants with deliveries between 2007 and 2019. Using 29,037 serial weight measures (median = 7/participant), we fit mixed-effect models to predict weight at delivery. Total GWG (kg) was defined as the difference between the model-predicted weight at delivery and self-reported pre-pregnancy weight. We categorised GWG as below, within or above the 2009 BMI-specific guidelines. We analysed proportional trends in GWG categories: (a) overall and (b) stratified by maternal characteristics (pre-pregnancy BMI, race/ethnicity, educational level and parity). We analysed trends in covariate-adjusted geometric mean (GMs) of GWG using multiple linear regression.

The proportion of participants gaining weight within the GWG guidelines decreased from 46% in 2007-2008 to 24% in 2018-2019, which was driven by an increase in those gaining above the guidelines (40% to 73%). Across maternal characteristics, the largest increases of proportions above the guidelines were among those of normal pre-pregnancy BMI (19% to 62%) and of non-Hispanic Black (48% to 85%) or non-Hispanic White (37% to 74%) race/ethnicity. Consistently, GMs increased from 8.3 kg (95% confidence interval [CI] 6.3, 10.8) in 2007-2008 to 10.9 kg (95% CI 7.9, 14.9) in 2018-2019.

Results from this large cohort study provide evidence that fewer women have been meeting the revised GWG guidelines and more have been gaining above the recommendations.