Cesarean delivery raises infants' risk of RSV hospitalization

Children born by acute or elective cesarean delivery are more likely than infants delivered vaginally to develop respiratory syncytial virus (RSV) infection requiring hospitalization, according to a national register-based study conducted in Denmark.

Investigators followed the almost 400,000 children who were born during a 6-year period from birth to age 23 months or to their first RSV hospitalization. Of total births, 31,715 (7.9%) were by acute cesarean delivery and 30,965 (7.6%) by elective cesarean delivery. Respiratory syncytial virus hospitalizations in the whole group totaled 10,758 during the study period.

In comparing the association of method of delivery (acute or elective cesarean delivery, or vaginal delivery) with hospitalization for RSV disease, investigators adjusted for potential confounders, such as maternal smoking during pregnancy, prematurity, and early asthma diagnoses. Their analysis showed that infants born by acute cesarean delivery were 9% more likely to be hospitalized for RSV infection than those born vaginally, and for children born by elective cesarean delivery the increased likelihood was even greater-27%. For elective cesarean delivery, the increased hospitalization risk was the same in the first and second years of the child’s life, whereas for acute cesarean delivery, this risk increased only in the infant’s second year (Kristensen K, et al. Pediatr Infect Dis J. 2015;34[2]:145-148).

Commentary: The researchers propose as a possible explanation for this association one of the hottest new topics in the medical literature: the influence of changes to the human microbiome. Children born by cesarean delivery, especially those born by elective cesarean delivery without prior rupture of membranes, are not exposed to maternal vaginal flora. This alters microbial colonization of the infant’s gut, which may have an impact on developing mucosa immune defenses and immunologic priming. Watch for more developments on the role of the microbiome on a wide array of health conditions. -Michael G Burke, MD

Ms Freedman is a freelance medical editor and writer in New Jersey. Dr Burke, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. The editors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.