Early childhood atopic dermatitis (AD) occurred more frequently among children delivered by cesarean section or instrumental vaginal delivery compared with uncomplicated vaginal delivery, study data published in Pediatric Allergy and Immunology indicate.
Investigators from Karolinska Institutet in Sweden sourced data for this study from the Medical Birth Register, which included all singleton births (N=1,399,406) that occurred in Sweden from 2006 through 2018. Risk for early childhood AD, defined using the clinical algorithm published by Henriksen, was evaluated on the basis of mode of birth delivery. A subset of children (n=853,884) who had a sibling with shared maternity that was not included in the main analysis were included in a sibling analysis.
The study population comprised children with a mean age of 4.3 (standard deviation [SD], 1.3) years at the end of follow-up, 51.4% were boys, 50.7% were born at gestational week 39 to 40 and with a birth weight of 3511 (SD, 583) g, 82.2% were born by vaginal delivery, and the mother’s age at delivery was 30.4 (SD, 5.2) years.
Within the first year of life, 68,443 children born by vaginal delivery and 16,269 born by cesarean section were diagnosed with AD. After adjusting for cofounders, children born by cesarean section were at higher risk for AD compared with those born by vaginal delivery (adjusted hazard ratio [aHR], 1.12; 95% CI, 1.10-1.14).
In the analysis that incorporated additional delivery characteristics, risk for AD was higher among children born by instrumental vaginal delivery (aHR, 1.10; 95% CI, 1.07-1.13), emergency cesarean section (aHR, 1.12; 95% CI, 1.10-1.15), and elective cesarean section (aHR, 1.13; 95% CI, 1.10-1.16) compared with uncomplicated vaginal delivery.
Similar trends were observed for AD diagnosed after 1 year of age, in which risk was elevated for cesarean sections compared with vaginal deliveries (aHR, 1.05) and for instrumental vaginal deliveries (aHR, 1.04), emergency cesarean sections (aHR, 1.05), and elective cesarean sections (aHR, 1.06) compared with uncomplicated vaginal deliveries.
In the sibling analysis, cesarean section compared with vaginal delivery (aHR, 1.06) and instrumental vaginal delivery (aHR, 1.10) or emergency cesarean section (aHR, 1.11) compared with uncomplicated vaginal delivery were risk factors for AD within the first year of life. No delivery characteristics increased risk for AD after 1 year of age.
This study was potentially limited by not accounting for other confounding factors, such as paternal information.
“In our study population, it was observed that children born by caesarean section or instrumental vaginal delivery were at higher risk of early childhood atopic dermatitis,” researchers commented. Additional study is needed to determine the biological mechanisms of this trend.
Mubanga M, Lundholm C, Rohlin ES, et al. Mode of delivery and offspring atopic dermatitis in a Swedish nationwide study. Pediatr Allergy Immunol. 2023;34:e13904. doi:10.1111/pai.13904
This article originally appeared on Dermatology Advisor