Exploration of Diet Quality by Obesity Severity in Association with Gestational Weight Gain and Distal Gut Microbiota in Pregnant African American Women: Opportunities for Intervention

To conduct an exploratory examination of dietary patterns and quality during pregnancy in African-American women who were class I, II, or III obese, and those women with normal pre-pregnancy body mass index (pBMI), as well to identify dietary factors associated with GWG, and changes in the distal gut microbiome. African American women represent the largest group affected by pre-pregnancy obesity, a risk factor for several adverse birth outcomes. This prospective study investigated the association between diet, distal gut microbiome, and GWG among African-American women (n = 21) with obesity (n = 15) compared to women with a normal pre-pregnancy body mass index (pBMI) (n = 6) at two time points, 27–29 and 37–39 weeks gestation. Dietary patterns associated with obesity severity and GWG gain were assessed using Welch’s T-test and Mann–Whitney U. The association between the gut microbiome and dietary patterns was assessed using a regression-based kernel association test and the adaptive microbiome-based sum of powered score test. In early pregnancy, dietary intake of Total Fruits and Greens and Beans was significantly different between pBMI and GWG groups; significance was 0.022 and 0.028 respectively. Women with Class II/III obesity and those with GWG above guidelines had Healthy Eating Index (HEI) scores below 50, meeting less than 75% of dietary guidelines, and did not meet recommendations for fruit and vegetable or fiber intake. We found no significant associations between the microbiome composition and diet (HEI Scores). Overall, the results indicate that women with pBMI obesity are not meeting minimum dietary guidelines for nutrient intakes during pregnancy, specifically fruits, vegetables, and fiber, regardless of GWG. Interventions for African-American women with pre-pregnancy obesity, with a focus on increasing consumption of fruits and vegetables, would be beneficial to control GWG and improve birth outcomes.