The HAHSO funds have supported the Baby & Mi study in which we are evaluating the influence of early life exposures, including antibiotics, on the developing gut microbiome.  The success of this initial study has translated into subsequent funding success allowing us to expand the cohort to 240 mother-infant pairs, to extend our follow-up to 3 years (CIHR Operating Grant), to begin to study preterm infants and to collaborate with European colleagues to answer important questions on the influence of early nutrition on the gut microbiome and infant and child health (Joint Programming Initiative “A Healthy Diet for a Healthy Life” Strategic Research Agenda).  The HAHSO funds have catalyzed a research program that will advance the scientific dialogue around early gut microbiota development, and have implications to clinicians, governmental organizations, policy makers and pregnant women and their families.

Background: The intestinal microbiome (IM) influences metabolic, nutritional, and immunologic processes and has been linked with adverse health outcomes including asthma, obesity and Type 2 diabetes. Early life exposures may alter the course of gut microbial colonization leading to differences in metabolic and immune regulation throughout life. While approximately 50% of Canadian low-risk full-term infants are exposed to intrapartum antibiotics (IAP), the influence of this prophylactic treatment on the developing neonatal IM is elusive. The objectives of this study are: a) to describe the IM over the first 3 years of life among healthy, breastfed infants born to women with low-risk pregnancies at full term gestation and b) to determine if the IM of infants exposed to IAP differs in type and quantity from that of unexposed infants.

Methods: A prospective cohort of 240 mother-infant pairs (followed to 3 years of age) is being established by enrolling pregnant women from local midwifery practices. Eligibility includes low-risk women, planning a vaginal birth and able to communicate in English. Study questionnaires, anthropometric and body composition measures, and biological samples are collected including 8 stool samples.

Results to date: Bacterial communities within infants exposed to IAP were delayed in colonization with Bifidobacterium and retained higher levels of Escherichia compared with unexposed infants. Differential effects on Bacteroidetes colonization over time were also observed. There was a direct correlation between IAP exposure duration and delay in colonization; every additional hour of IAP exposure prior to birth resulted in a 7.2% decrease in the abundance of Bifidobacterium, a 3.4% increase in Bacteroides and a 2.5% increase in the abundance of Clostridium in the IM at 12 weeks of age.