For a study, the gut microbiota of newborns was connected to their short-term growth and maybe future health, or highly influenced by their intrinsic host microenvironmental variables (e.g., gestational age). It was unclear whether the microbiota composition of newborns produced by assisted reproductive technology (ART) differs substantially from that of naturally conceived infants. Furthermore, nothing was known regarding the impact of gut microbiota composition on early childhood weight gain. In mother-infant dyads enrolled in the National Birth Cohort, the researchers wanted 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 early infancy (CNBC). The researchers 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. Individual ART therapies influenced the microbiota composition of ART neonates which implied the effect 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, demonstrating the importance of microbiota composition in neonatal growth.