C-Section Deliveries Are Not Linked to the Increased Risk of Allergic Diseases

A study found no association between cesarean delivery and childhood atopic dermatitis, food allergy, bronchial asthma, or allergic rhinoconjunctivitis.1

“This finding is inconsistent with the results of systematic reviews that analyzed this association,” noted investigators in their report, led by Kei Tamai, from Okayama University.

In Japan, both cesarean delivery rates and allergic diseases continue to rise. C-section deliveries have increased in Japan from 18.4% in 2008 to 21.6% in 2020. A 2023 online questionnaire found that nearly two-thirds of the Japanese population may have an allergic disease (62.2%).2

Studies have shown a potential association between c-sections and allergic conditions, although these were conducted in Western countries—not in Asia.1 However, investigators noted that differences in cultural practices, lifestyles, and genetic backgrounds could impact the association. Since the early 2000s, Japan has had stable rates of atopic dermatitis and bronchial asthma, a decline in wheezing and eczema, and a rise in food allergy and allergic rhinitis.

Investigators wanted to see if, like in other regions, children born from c-section deliveries had an increased risk of allergic diseases, including atopic dermatitis, food allergy, bronchial asthma, and allergic rhinoconjunctivitis. The primary outcomes were atopic dermatitis, food allergy, and bronchial asthma during childhood for each age group up to 9 years old.

The team analyzed population-based data of 2114 children (53.3% male) born in Japan between May 10 – 24, 2010, from the Longitudinal Survey of Babies in the 21st Century, linked to the Perinatal Research Network Database. The study compared the risk of allergic diseases in children born by c-section vs those born vaginally.

The allergic disease status was tracked via surveys each year up until the child reached 9 years old. Investigators examined whether there was at least 1 visit for one of the 4 allergic diseases during the following age intervals: 6 months to 1.5 years, 1.5–2.5 years, 2.5–3.5 years, 3.5–4.5 years, 4.5–5.5 years, 5.5–7 years, 7–8 years, and 8–9 years. From 0.5 to 9 years, 10.4% of children had atopic dermatitis, 8.4% had food allergy, 15% had bronchial asthma, and 36.5% had allergic rhinoconjunctivitis.

When looking at mode of delivery, children with vaginal births had slightly greater rates of food allergy (2.7%), atopic dermatitis (5.5%), bronchial asthma (6.3%), and allergic rhinoconjunctivitis) than children born from c-sections.

The generalized estimating equations analysis found that children born by c-section did not have a greater risk of atopic dermatitis (adjusted risk ratio [aRR], 0.8; 95% confidence interval [CI], 0.5 – 1.2), food allergy (aRR, 1.1; 95% CI, 0.7 – 1.7), bronchial asthma (aRR, 1.0; 95% CI, 0.8 – 1.4), and allergic rhinoconjunctivitis (aRR, 0.9; 95% CI, 0.8 – 1.1) compared with children born vaginally.

Investigators theorized that the discrepancy between this study and other studies on c-sections and asthma risk may stem from differences in sample size, healthcare systems, clinical criteria, and population characteristics. They wrote that Japan’s universal healthcare, lower c-section rates, and contextual factors may reduce the impact of delivery method on allergy development.

“Therefore, our findings should be interpreted in light of these country-specific differences,” investigators wrote. “Further studies with larger samples are required to validate our findings and to determine how they differ from other studies.”

References

1. Tamai K, Matsumoto N, Mitsui T, Masuyama H, Yorifuji T. Association between cesarean delivery and childhood allergic diseases in a longitudinal population-based birth cohort from Japan. Sci Rep. 2025;15(1):19206. Published 2025 Jun 1. doi:10.1038/s41598-025-03703-3

2. Ito Y, Kato T, Yoshida K, Takahashi K, Fukutomi Y, Nagao M, Fukuie T, Matsuzaki H, Gotoh M, Tanaka A, Konno S, Tezuka J, Nakamura Y, Adachi Y. Prevalence of Allergic Diseases across All Ages in Japan: A Nationwide Cross-Sectional Study Employing Designated Allergic Disease Medical Hospital Network. JMA J. 2023 Apr 14;6(2):165-174. doi: 10.31662/jmaj.2022-0218. Epub 2023 Mar 24. PMID: 37179734; PMCID: PMC10169263.