Environmental Tobacco Smoke Exposure and Breastfeeding Duration Influence the Composition and Dynamics of Gut Microbiota in Young Children Aged 0–2 Years

The colonization characteristics of infant gut microbiota are influenced by many factors at various stages, but few studies have explored the longitudinal effects of environmental tobacco smoke exposure and quantitative breastfeeding duration on young children’ gut microbiota. We explored the effects of smoke exposure and breastfeeding duration on gut microbiota by following 37 maternal and children pairs in China for 2 years. We collected the demographic information, frequency of smoke exposure, breastfeeding duration, and fecal samples (mothers in the late pregnancy and infants at 6, 12, and 24 months), and analyzed the microbiota results using the V3-V4 gene sequence of 16S rRNA. The diversity of gut microbiota in children was the highest at 24 months and most similar to that in mothers. Breastfeeding duration was positively correlated with Lactobacillus and negatively correlated with Clostridium_sensu_stricto_1. The α diversity of microbiota and the relative abundance of [Ruminococcus]_gnavus_group was higher in the non-smoke exposed group. The higher the smoke exposure, the higher the relative abundance of Megasphaera. Prolonged breastfeeding and reduced smoke exposure are beneficial to the diversity and composition of gut microbiota in young children.