Improvement in Maternal Diet Quality Across Pregnancy Is Associated With Lower Gestational Weight Gain in Women With Obesity From the Illinois Kids Development Study

Background It is unclear how diet is associated with gestational weight gain (GWG) because prior studies focused on individual foods and did not consider diet at multiple timepoints. Objective The current study aimed to evaluate associations between changes in diet quality across pregnancy with GWG. Design This secondary data analysis included women from the Illinois Kids Development Study – a longitudinal prospective cohort. Participants /setting: Participants were 380 women recruited 2013-2018 from obstetric clinics in Champaign-Urbana, Illinois who were followed through delivery. Main outcome measures At median 13- and 35-weeks gestation, participants completed three-month semi-quantitative food frequency questionnaires to calculate the Healthy Eating Index (HEI)-2015 and Alternative Healthy Eating Index (AHEI)-2010 excluding alcohol. Change in diet quality was calculated by subtracting diet quality scores at 13-weeks from those at 35-weeks. Gestational age- and pre-pregnancy BMI-specific GWG z-scores were calculated using weight before pregnancy and at median 38-weeks gestation along with an international reference chart. Using pre-pregnancy BMI (kg/m 2 ), women were classified as having under-/healthy weight (