Objectives : Determine if the infant gut microbiota at 12 months of age is associated with maternal pre-pregnancy BMI or infant human milk (HM) exposure. Additionally, determine whether infant BMI z-score at 12 months is associated with the infant microbiota composition and richness at 6 and 12 months.
Methods : Fecal samples were collected from infants at 6 (n=35) and 12 (n=32) months of age. Maternal pre-pregnancy BMI, infant weight and height, and the amount of HM in the infant diet were self-reported. Infant BMI for age z-scores (BAZ) were calculated using WHO Anthro software. Fecal communities were analyzed by 16S rRNA (V4) sequencing on an Illumina Miseq.
Infants who had HM at 12 months had lower microbiota richness than infants who only received it until 6 months or were not exposed. Microbial community membership (Sorensen) was also significantly different in infants who received any HM at 12 months compared to infants who only received it until 6 months or were not exposed. The 12-month microbiota was similar for infants who received HM until 6 months or had no exposure. Infant BAZ at 12 months positively correlated with maternal pre-pregnancy BMI. Fewer infants born to obese women were exposed to HM at 12 months compared to those born to normal weight women. However, HM exposure at 12 months was not associated with infant BAZ at 12 months. In the 12-month microbiota, Shannon diversity also positively correlated with maternal pre-pregnancy BMI. No alpha or beta diversity metrics of the infant microbiota at 6 months were associated with infant BAZ at 12 months. However, the Shannon diversity of the 12-month microbiota tended to be positively associated the 12-month infant BAZ.
Conclusions : Maternal pre-pregnancy BMI was associated with higher gut microbiota diversity at 12 months of age. This increase in diversity may influence host metabolism, providing a mechanistic link for elevated BAZ in infants whose mothers had an elevated BMI prior to becoming pregnant.
Funding Sources : Michigan State AgBioResearch, Child Health Advances through Research with Mothers, Michigan Health Endowment Fund, and the NIH Environmental Influences on Child Health Outcomes (ECHO) Program (Prenatal Exposures and Child Health Outcomes: A Statewide Study (UG3 OD023285)).