Little is known about how physical contact at birth and early caregiving environments influence the colonization of the infant gastrointestinal microbiome. We investigated how infant contact with caregivers at birth and within the first 2 weeks of life relates to the composition of the gastrointestinal microbiome in a sample of U.S. infants (n = 60).
Skin-to-skin and physical contact with caregivers at birth and early caregiving environments were surveyed at 2 weeks postpartum. Stool samples were collected from infants at 2 weeks, 2, 6, and 12 months of age and underwent 16S rRNA sequencing as a proxy for the gastrointestinal microbiome. Associations between early caregiving environments and alpha and beta diversity, and differential abundance of bacteria at the genus level were assessed using PERMANOVA, and negative binomial mixed models in DEseq2.
Time in physical contact with caregivers explained 10% of variation in beta diversity at 2 weeks' age. The number of caregivers in the first few weeks of life explained 9% of variation in beta diversity at 2 weeks and the number of individuals in physical contact at birth explained 11% of variation in beta diversity at 6 months. Skin-to-skin contact on the day of birth was positively associated with the abundance of eight genera. Infants held for by more individuals had greater abundance of eight genera.
Results reveal a potential mechanism (skin-to-skin and physical contact) by which caregivers influence the infant gastrointestinal microbiome. Our findings contribute to work exploring the social transmission of microbes.
Wiley, K. S., Gregg, A. M., Fox, M. M., Lagishetty, V., Sandman, C. A., Jacobs, J. P., & Glynn, L. M. (2023). Contact with caregivers is associated with composition of the infant gastrointestinal microbiome in the first 6 months of life. American Journal of Biological Anthropology, 1–17. https://doi.org/10.1002/ajpa.24858
Figure S1. Changes in infant fecal microbiota at different ages during the first year of life. (a) and (b) Box and whisker plots of alpha diversity as measured by (a) Chao1 index (species richness) and (b) Shannon index. P-values for alpha diversity differences by age were determined by one-way ANOVA (analysis of variance) after adjusting for subject. Median is represented by the dividing line, mean is represented by the x. First and third quartiles are represented by lower and upper edge of the boxes respectively. (c) Principal coordinates analysis plots of microbial beta diversity measured by Shannon divergence distances. Each symbol represents a sample that is colored by age at the time of sample collection. P value for beta diversity differences by age was calculated using PERMANOVA (permutational multivariate analysis of variance) after adjusting for subject. (d)–(f) Stacked bar charts showing mean relative abundance in each age group of bacterial (d) phyla, (e) families, and (f) genera. Others indicate sum of taxa present at less than 2% in mean relative abundance averaged over different age groups.
ajpa24858-sup-0002-tables.docx (35 kB)
Supplemental Table 1: Questionnaire Items Supplemental Table 2: Independent Variables Supplemental Table 3. Alpha diversity association with caregiver contact using multivariate linear regression models adjusting for infant sex, mode of delivery, and breastfeeding. Supplemental Table 4. Differential abundances at two weeks associated with the amount of time spent in physical contact at 2 weeks. Supplemental Table 5. Differential abundances at two weeks associated with skin-to-skin contact initiated immediately after birth. Supplemental Table 6. Differential abundances at two weeks associated with the total number of caregivers actively caring for the infant. Supplemental Table 7. Differential abundances at six months associated with the number of caregivers that regularly hold the infant. Supplemental Table 8. Differential abundances at six months associated with the total number of caregivers who held the newborn on the day-of-birth
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