For a study, the gut microbiota of newborns was connected to their short-term growth and maybe future health, and maybe highly influenced by their intrinsic host microenvironmental variables (e.g., gestational age). It was still unknown whether the early microbiota composition of newborns created by assisted reproductive technology (ART) differed significantly from those conceived naturally. Furthermore, nothing was known regarding the impact of gut microbiota composition on early childhood weight gain. In mother-infant dyads enrolled in the China National Birth Cohort (CNBC), the researchers aimed to define the features and drivers of the gut microbiome in ART babies, as well as analyze the impact of early microbiota composition on their weight gain in young infants. It was found that ART neonates had significantly lower gut microbiota diversity and Bacteroidetes relative abundance than spontaneously conceived neonates, with 118 ART neonates having significantly lower gut microbiota diversity and 91 spontaneously conceived neonates having significantly higher Bacteroidetes relative abundance. The microbiota composition of ART neonates was considerably influenced by individual ART therapies, implying the impact of the fetus’s inherent host microenvironment on microbial colonization early on. The researchers evaluated the effects of gut microbiota composition on baby fast weight gain by following these neonates for six months after birth. The researchers discovered characteristics and drivers of gut microbiota composition in ART neonates, emphasizing the significance of microbiota composition in neonatal growth.