乌鸦传媒

Babies born via cesarean section were hospitalized more often in early childhood for infection, compared with those delivered vaginally, an international study found.

With more than 7 million children included in the analysis, the hazard ratio for infection-related hospital visits was 1.10 (95% CI 1.09-1.12) for children delivered by C-section versus vaginal birth, reported Jessica Miller, PhD, of the Murdoch's Children Research Institute and the University of Melbourne in Australia, and colleagues.

The increased risk persisted until children were 5 years old, and it was highest for respiratory, gastrointestinal, and viral infections, the researchers reported in .

"Our findings, if causal, suggest that about 2%-3% of children with infection-related hospitalisations in our study could attribute their infection to being born by cesarean section," Miller told 乌鸦传媒 in an email. "As infection is the leading cause of early childhood hospitalisation, even small reductions in infection rates would make a difference to the overall health of populations."

Miller said the consistency of these findings across four different regions with a range of C-section rates -- 17% in Denmark to 29% in Western Australia -- was "striking." But she contended that cesarean delivery is still the safest option for some mothers and babies even with the increased risk of infection.

She cited different effects on the infant microbiome from C-section versus vaginal birth as a potential explanation for the study findings. Bacteria from the mother and the environment both seed the infant's initial microbiome, and these may influence a child's subsequent immune development.

As C-sections accelerate worldwide, the long-term effects on infant and maternal health are not well understood. While previous studies have linked cesarean births to asthma or other specific infections, Miller's group aimed to investigate how this mode of delivery was associated with infection-related hospitalizations overall.

Miller and colleagues gathered data from births in Denmark, Scotland, England, and Australia, spanning 1996 to 2015. They grouped births by mode of delivery -- C-section or vaginal -- and linked them to hospitalization records within the first 5 years of a child's life. Infections were coded as invasive bacterial, skin and soft tissue, genitourinary, upper respiratory tract, lower respiratory tract, viral infections, and gastrointestinal.

Miller's group adjusted for potential confounders including maternal smoking, parity, birthweight, season of birth, gestational age, and socioeconomic status. Children born with congenital anomalies were excluded from their analysis.

Among the 7,174,787 births included, about one-quarter were C-sections. Rates of C-section rose during the study period for both elective and emergency procedures. Overall, 43% of C-sections were elective.

More than 1.5 million children had at least one infection-related hospitalization during the follow-up period. Childhood admissions for infection were increased with C-section delivery with both elective (HR 1.13, 95% CI 1.12-1.13) and emergency (HR 1.09, 95% CI 1.06-1.12) procedures, relative to vaginal birth.

Risk was similar when the researchers compared children whose mothers who did versus did not go into labor before delivery.

Children born via C-section had higher risks for all types of clinical infections, but it was most pronounced for gastrointestinal, respiratory, and viral infections. In a sensitivity analysis of mothers who were at low obstetric risk, Miller and colleagues also observed increased risk of infection in children born by C-section.

The researchers cited changes in lifestyle and obstetric guidelines that occurred over the course of the study period as a potential limitation, along with the potential for unmeasured confounding.

Miller said future studies should delve further into mechanisms by which C-section birth may promote later infections. Such research should examine interventions such as breastfeeding, she suggested, as well as focus on lower and middle income countries where infection is more prevalent.

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