Between August 2017 and April 2019, 303 women in their first or second gestational trimester were enrolled in an interventional randomized controlled trial to investigate the outcomes associated with dietary plans with different proportions of total carbohydrates. Eligible women were aged 18 to 45 years old who did not have a high risk pregnancy, chronic renal disease, cancer, congestive heart failure, diabetes, or hypertension. Participants were randomized by sequential assignment at their baseline study visit into a group which either ingested refined grains or whole grains as 75% of their total carbohydrate intake. A majority of enrolled women self-identified as Hispanic and spoke Spanish as their primary language—a registered dietitian specializing in Hispanic diet counseling provided pregnancy diet materials featuring ethnically appropriate foods. Outcome measures included changes in maternal weight, preterm birth rate, neonatal weight, blood pressure, blood glucose, and diet compliance.

This dataset includes 16S rRNA microbiome data collected from 103 women who consented to provide 108 vaginal and 109 anal swabs. The swabs were performed at baseline before participants began their prescribed diets and after 17 to 32 weeks of dietary intervention (aligning with their third trimesters). 5,113,342 high quality 16S V4 region reads were generated with an average number of 27,054 reads per sample.