Catch-Up Weight Gain and Gut Microbiota Development in Full-Term Small for Gestational Age Children During the First Year of Life-A Prospective Cohort Study.

SGA infants exhibited higher alpha diversity than AGA children at most time points during the first year of life.

• The study included 19 full-term SGA and 46 full-term AGA infants in a longitudinal cohort design.
• Gut microbiota composition was analyzed using 16S rRNA gene sequencing.
• Stool samples and body mass measurements were collected at multiple time points during the 1st year of life.
• Alpha diversity was assessed as one of the primary measures of microbial composition.

In SGA infants, the Shannon index was positively associated with the rate of body weight gain over time.

• The association between Shannon index and rate of body weight gain was statistically significant (p = 0.015).
• The Shannon index was used as a measure reflecting the level of gut microbiota maturation.
• This positive association between microbiota maturity and weight gain rate was not observed in AGA infants.
• The finding suggests that more mature microbiota corresponded to faster catch-up weight gain in SGA infants.

SGA infants had characteristic genera that distinguished their gut microbiota from AGA infants.

• Genera associated with SGA included Citrobacter, Staphylococcus, Blautia, Veillonella, Klebsiella, and Clostridium XIVa.
• Some of these genera are known short-chain fatty acid-producing bacteria.
• Some of these genera are associated with obesity in the literature.
• Beta diversity analysis was used alongside taxa abundances to evaluate differences in microbial composition between groups.

SGA children had a distinct gut microbiota community composition compared to AGA peers.

• Both alpha diversity, beta diversity, and taxa abundances were used to evaluate microbial composition and diversity across developmental stages.
• The distinct microbiota profile was observed across multiple time points during the first year of life.
• The study design was prospective and longitudinal, with 19 SGA and 46 AGA full-term infants.

Early microbial development in SGA infants may affect the risk of overweight and obesity later in life.

• More mature microbiota in SGA infants was linked to faster weight gain and increased abundance of short-chain fatty acid-producing and obesity-associated bacteria.
• The association between gut microbiota maturation and catch-up weight gain was specific to the SGA group.
• Blautia, Veillonella, and Clostridium XIVa are among the genera identified as characteristic of SGA infants and are associated with metabolic outcomes.
• The authors suggest this link between microbial composition and growth trajectory may have implications for long-term metabolic risk.