Supporting your newborn's health: Intestinal colonization after elective cesarean section

This month we recognize World Microbiome Day with information to help new parents learn about their baby's developing bacteria colonization and how interventions in the first 1,000 days of life may affect their child's risk of developing preventable autoimmune conditions.

As I have discussed in a previous blog, the microbiome — the varied and teeming colonies of gut bacteria inside of us — is greatly influenced from the time of our conception until the second year of life, and the development and colonization of the microbiome during the first 1,000 days of life can profoundly affect our health during infancy through adulthood.

Major microbiome colonization begins with delivery

Each method of delivery — vaginal birth or delivery by cesarean section — produces a different colonization pattern. The nature of intestinal colonization after birth has a profound effect on a newborn's capacity to develop intestinal protection against infection and inflammatory disease. A critical step in an infant's colonization process comes from ingesting maternal microbiota when passing through the birth canal. If an infant is born by an elective cesarean section rather than vaginal delivery, the colonizing bacteria are strikingly different, as there is less diversity of bacteria and fewer health-promoting bacteria.

How does this difference in colonizing bacteria affect an infant's health and risk of disease?

A major study from Denmark examined the development of chronic immune diseases over a 30-year span in over two million children born either by cesarean section or by vaginal delivery, using the National Registry database. There was a striking difference in the development of allergy, juvenile arthritis, and immune deficiencies over the first five years of life in children born via cesarean section versus vaginal delivery.

This study confirms meta-analyses of smaller studies in the United States that suggest that cesarean section deliveries are risk factors for development of allergy and autoimmune disease. Elective cesarean section deliveries have increased from 5% in 1970 to 25% in 2010 in the US, while at the same time the incidence of autoimmune diseases has increased in Western society over the last several decades, and there may be a correlation.

Altered intestinal colonization in medically-indicated vs. elective cesarean sections

We have learned that major changes in intestinal colonization occur after elective cesarean sections (those done for the convenience of the patient or doctor), and not in medically-indicated cesarean sections (because of failed labor or other stress to the newborn). An expectant mother should be thoughtful about electing to do a cesarean section if vaginal delivery is an available and medically safe alternative.

How can new parents manage altered colonization after an elective cesarean section to support their newborn's developing microbiome?

Colonization is affected by diet (breast milk vs. formula) and weaning to solid foods. Mothers should strongly consider breastfeeding, since breastfeeding helps establish natural colonization.

• Established clinical probiotics such as Lactobacillus acidophilus and Bifidobacterium infantis can be given either to lactating mothers or to newborns.
• A swab from a new mother's vagina can be placed into the mouth of the newborn following delivery, presumably to help establish the colonization from mother's cavities. This approach is still experimental and isn't routinely recommended.

Women who elect or have a medically-indicated cesarean section birth may receive a course of antibiotics, which further alters the composition of colonizing bacteria. In future blogs, I will discuss the effect of antibiotics on colonization and suggest new approaches to optimize ongoing colonization.

References

Cesarean section and chronic immune disorders. Pediatrics, January 2015.

Maturation of the infant microbiome community structure and function across multiple body sites and in relation to mode of delivery. Nature Medicine, January 23, 2017.

Cesarean Versus Vaginal Delivery: Long-term Infant Outcomes and the Hygiene Hypothesis. Clinics in Perinatology, June 2011.