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

Abstract

Background: 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.

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

Methods: 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.

Results: 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.

Conclusions: 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.