Grant: Operating Grant

The World Health Organization recommends that the rate of Cesarean section (CS) should be no higher than 15% and that infants should not be fed anything other than breast milk for the first 6 months. Currently in Canada, 27% of births are by CS, up from 18% in the mid 1990s. Also, only 14% of Canadian infants are strictly breastfed for the first six months of life and less so if they are born by CS. The consequences of decision-making around birth method and infant feeding should not be underestimated. Beyond risks to the mother and infant at the time of delivery, long term health effects are associated with CS birth, including allergy, asthma and overweight. Breastfeeding provides health benefits to the child by reducing the risk of these conditions. It is thought that health outcomes related to CS and breastfeeding may be due to changes in the bacteria living in the intestinal tract, called the gut microbiota. This community of beneficial bacteria evolves in response to the bacterial environment of the infant. Normally, the first exposure to microbes is the bacteria encountered in the birth canal. In a CS-delivered infant, exposures come from the mother's skin and hospital environment. Antibiotic treatment to prevent infection in CS may also affect the development of infant gut microbiota. A clearer understanding is needed of how the gut microbiota is affected by birth method and early feeding, and how these changes affect the health of the child later in life. The main goal of our research in 3,300 healthy Canadian infants is to understand long term child health outcomes arising from changes in the development of the infant gut microbiota in response to CS delivery. A secondary goal is to determine how other factors, like breastfeeding and antibiotic use, alter the effects of CS on the infant gut microbiota. This will help parents and physicians make more informed decisions about birth method and infant feeding.