Researchers in Japan investigated the associations between cesarean delivery and the development of eczema, wheezing, asthma, and atopic dermatitis in Japanese infants.
Study
The incidence of allergic diseases has recently increased worldwide. In Japan, allergic diseases are a significant health concern, with high rates of atopic dermatitis, wheezing, and asthma observed in children. Meanwhile, the rates of cesarean delivery have also increased globally. Children born by cesarean delivery exhibit an altered cytokine profile and gut flora compared to those born vaginally, though the clinical significance of these differences remains debated.
In the present study, researchers investigated associations between cesarean delivery and the development of eczema and wheezing among Japanese infants. The team utilized data from the Japan Environment and Children's Study (JECS), an extensive cohort study examining the impact of environmental factors on child health. The JECS included 103,062 pregnancies between January 2011 and March 2014.
The current study used the March 2018 dataset of the JECS and excluded those with miscarriage, multiple babies, or stillbirth. Self-reported questionnaires were administered to collect information about pregnancy and children. Atopic dermatitis, wheezing, asthma, and eczema were assessed based on information provided when the children were one year old. Participants were assigned to the vaginal or cesarean delivery group based on the delivery mode.
Findings
The study included 74,639 mothers from the JECS. Of these, 81.6% underwent vaginal delivery and 18.4% underwent cesarean delivery. Among cesarean deliveries, 41.4% were emergency and 58.6% were elective deliveries. In infants born by cesarean delivery, the rates of atopic dermatitis, asthma, eczema, and wheezing were 4.2%, 2.7%, 18.1%, and 20.2%, respectively.
The corresponding rates in those born by vaginal delivery were 4.4%, 2.5%, 19%, and 19.5%, respectively. GA less than 39 weeks, parity two or more, SGA, maternal age at pregnancy 30 or older, maternal smoking during pregnancy, higher maternal education, higher annual family income, and pet ownership were associated with an increased incidence of cesarean delivery. In contrast, breastfeeding at six months and primipara were associated with a reduced incidence of cesarean delivery.
Adjusted regression analyses revealed that cesarean delivery was not associated with a higher risk of wheezing, asthma, atopic dermatitis, or eczema in infants. All adjusted odds ratios had 95% confidence intervals that included 1.0. Similarly, elective delivery was not associated with an increased risk of eczema, wheezing, atopic dermatitis, or asthma. However, emergency delivery was associated with a reduced odds of eczema (adjusted odds ratio 0.91, 95% confidence interval 0.85 to 0.98), representing a modest 9% reduction in risk.
Conclusion
Taken together, cesarean delivery was not associated with the development of eczema or wheezing in infants up to the age of 1. Similarly, emergency and elective cesarean deliveries did not increase the odds of eczema and wheezing.
The study treated eczema, defined as a recurrent itchy rash, and atopic dermatitis, defined as a clinician-diagnosed condition, as separate outcomes, a distinction relevant for clinical interpretation.
The study's limitations include the use of self reported data, which may have resulted in underreporting, a narrow outcome definition window within the first year of life, which may be too early to observe associations, particularly for asthma, which is difficult to diagnose reliably in infants, lack of data on disease severity, and potential unmeasured confounding, including possible misclassification between elective and emergency cesarean deliveries.
The authors frame these null findings as strong evidence against a meaningful association between cesarean delivery and the development of early allergic disease.
Source:
https://www.news-medical.net/news/20251113/Cesarean-births-do-not-raise-infant-allergy-risk-in-major-Japanese-cohort-study.aspx