Cesarean section delivery has a short-term effect on asthma and wheezing in children under 2 years of age that may persist through adolescence, according to meta-analysis findings published in Respiratory Medicine.
Investigators in China aimed to characterize long-term and short-term effects of cesarean section on childhood asthma and wheezing. To accomplish this, the researchers conducted a study of children in China and synthesized their findings with a meta-analysis of existing literature on this topic.
For their original study, the researchers analyzed a cohort of 6501 infants seen at 30 days of age (baseline) at 15 vaccination clinics in Jinan, Shandong, China, from January 2018 to December 2019. Of that cohort, 2961 (45.5%) children were born via cesarean section. (Notably, this percentage is far above the global average rate of 18.6%, said the study authors). Children were followed-up at 2 years of age for respiratory diseases. A logistic regression model was used to estimate the effect of cesarean section on asthma and wheezing.
The researchers noted a 1.3% cumulative incidence of asthma and wheezing (1.35% in those with a cesarean section delivery; 1.24% in those born via vaginal delivery). The odds of cesarean section delivery affecting the asthma and wheezing status of children under 2 years of age was not significant (adjusted odds ratio [aOR], 1.14; 95% CI, 0.73-1.78; P =.78). Notably, boys demonstrated a significantly higher incidence of asthma and wheezing than girls (1.6% vs 0.9%; P =.015).
Meta-analysis found that cesarean section has a long-term effect on asthma and wheezing, which persisted up to the age of 18 years.
For meta-analysis purposes, investigators conducted a search of PubMed, Web of Science, and Medline databases from inception to May 2022 for observational studies involving participants (up to 18 years of age) born via vaginal delivery or cesarean section that reported on outcomes of asthma or persistent wheezing. The researchers identified 56 studies (more than 5.3 million participants) that showed incidence of asthma and wheezing, varied by age group (3.6%, 0-2 years; 7.8%, 2-4 years; 3.7%, 4-12 years; 0.55%, 12-18 years).
The meta-analysis, which included both the 56 studies identified for analysis and the investigators’ original research, showed cesarean section was a risk factor for asthma and wheezing for children under 2 years of age (OR, 1.15; 95% CI, 1.05-1.25; I2=46.82%).
Among children over 2 years of age, the meta-analysis found that cesarean section increased the risk for asthma and wheezing with substantial heterogeneity (OR, 1.17; 95% CI, 1.11-1.24; I2=79.38%). Investigators noted a significant overall effect of cesarean section on childhood asthma and wheezing with considerable heterogeneity (OR, 1.19; 95% CI, 1.14-1.24; I2=84.12%). Both emergency and elective cesarean section was associated with increased risk of asthma and wheezing in children, with the risk higher for emergency cesareans.
The odds ratio of cesarean section affecting asthma and wheezing in univariate analysis was 1.09 (95% CI, 0.71-1.67). Study authors noted cesarean section trended to increase risk of asthma and wheezing without statistical significance in the multivariate logistic regression model (aOR, 1.17; 95% CI, 0.75-1.80). Somewhat stronger associations (lacking statistical significance) were noted among children who were female vs male when stratified by child sex.
Study limitations include the use of a preponderance of studies conducted in Europe for the meta-analysis.
“Cesarean section was found to have a tendency to increase the risk of asthma and wheezing before 2 years of age, and when our results were pooled with previous literature, cesarean section was found to increase the risk of asthma and wheezing before the age of 2,” investigators concluded. They added, “Meta-analysis found that cesarean section has a long-term effect on asthma and wheezing, which persisted up to the age of 18 years.”