Cesarean delivery is associated with an increased risk of childhood asthma hospitalization in premature infants

Cesarean delivery is associated with an increased risk of childhood asthma hospitalization in premature infants, but not in full-term infants, according to a report published in this month’s Annals of Allergy, Asthma & Immunology, the scientific journal of the American College of Allergy, Asthma and Immunology (ACAAI).

The investigation by Jason S. Debley, M.D., M.P.H., and colleagues at the University of Washington, Seattle, provides new insight into why cesarean delivery may predispose an infant to having asthma. Previous study results on the association between mode of birth and asthma are conflicting, and do not take into account the effects of prematurity and maternal asthma according to the investigators.

Cesarean delivery alters the bacterial colonization of the gut, which normally occurs shortly after birth and may have a protective effect against the predisposition to asthma and allergies. Some investigators suggest that modification of the bacterial colonization by cesarean delivery may hinder the infant’s tolerance to allergenic substances and increases the risk of asthma, in agreement with the hygiene hypothesis.

When analyzed separately, Dr. Debley and colleagues found a significant association between cesarean delivery and asthma hospitalization in premature infants, but not in full-term infants. They also reported that, since women with asthma have higher rates of both premature infants and cesarean delivery, premature infants are more likely than full-term infants to have a maternal genetic predisposition for asthma.

The study evaluates more than 10,000 children aged 6 to 12 years using the Washington State Birth Events Record Database linked to state-wide hospitalization data.

Jonathan E. Spahr, M.D., and Marzena Krawiec, M.D., at the University of Wisconsin, Madison, noted in a separate guest editorial in the journal that the “identification of prematurity as a potential risk factor of asthma in terms of physiologic airflow obstruction may have implications for aggressive treatment.”

The study was supported by a grant from Maternal and Child Health Bureau, Health Resources and Services Administration, Department of Health and Human Services, and a National Research Service Award grant.