The goal of a new study published in The Journal of Pediatrics was to determine the association between diet during pregnancy and infancy, including breastfeeding versus formula feeding, solid food introduction, and infant intestinal microbiome. This study included 323 infants and their mothers participating in the Vitamin D Antenatal Asthma Reduction Trial. Here, maternal and infant diets were assessed by a questionnaire. Infant stool sequencing was performed; analyses were stratified by race/ethnicity. The findings showed that breastfeeding was independently associated with infant intestinal microbial diversity, when compared to formula feeding. Breastfeeding also had the most consistent associations with individual taxa that have been previously linked to early-life diet and health outcomes, such as Bifidobacterium. On the other hand, maternal diet during pregnancy and solid food introduction were less associated with the infant gut microbiome rather than the breastfeeding status. Furthermore, evidence of possible interaction between breastfeeding and child race/ethnicity on microbial composition was found. Hence, it was concluded that breastfeeding versus formula feeding is the dietary factor that is most consistently independently associated with the infant intestinal microbiome. Moreover, relationship between breastfeeding status and intestinal microbiome composition varies by child race/ethnicity.