C-Section Tied to Childhood Asthma?

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Children Born Via Cesarean Section May Be More Likely to Develop Asthma, Allergies

By Jennifer Warner
WebMD Health News

Reviewed By Louise Chang, MD

May 21, 2008 — Cesarean section rather than vaginal deliveries may raise the risk of childhood asthma and allergies by interfering with the child's immune system development, according to a new study.

Researchers say previous studies have suggested that babies born via C-section are more likely to develop childhood asthma and allergies, but the reasons are unclear.

This study suggests that babies born via C-section have impaired immune cell function because of suppression of regulatory T cells, which regulate the development and function of the immune system.

"This finding is exciting because it suggests that the mode of delivery may be an important factor influencing immune system development," researcher Ngoc Ly, MD, MPH, assistant professor of pediatrics at the University of California, San Francisco, says in a news release.

C-Section & Asthma Link Explained

In the study, presented at the American Thoracic Society's 2008 Conference in Toronto, researchers compared T cell suppression in a group of inner city newborns with a family history of asthma that put them at increased risk for childhood asthma.

Fifty of the children were born via C-section, and 68 were born vaginally. T cell suppression was measured by analyzing the child's cord blood.

The results showed that children born by cesarean section had a reduction in T cell suppression function compared with the other children. For example, the average T cell suppression index was 0.78 for children born via C-section and 1.11 for those born vaginally.

Ly suggests that the stress and process of labor itself or exposure to specific microbes through the birth canal in vaginal rather than C-section delivery may influence neonatal immune responses.

"These findings are preliminary and further work is needed to explore potential mechanisms for the association between mode of delivery and neonatal immune responses," Ly says. But researchers say this study provides a possible biological explanation for previous reports of the association between cesarean section and asthma.

SOURCES: American Thoracic Society 2008 Conference, Toronto, May 20, 2008. News release, American Thoracic Society.

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