Birth Order and Sibling Number Linked to Decreased Risk of Atopic Dermatitis

According to a study published in Clinical and Translational Allergy, being second-born or later with siblings may marginally decrease the lifetime risk of atopic dermatitis and food allergy.

Researchers aimed to investigate the association between birth order, sibship size (number of siblings), and the risk of atopic dermatitis and food allergy, which are common manifestations of atopy.

Out of 8819 papers obtained from database searches, 114 studies were included in the analysis. Independent pairs performed screening, data extraction, and quality assessment. Comparable numerical data were statistically synthesized using random-effects robust variance estimation. The findings revealed that being second-born or later (birth order ≥2) was associated with a lower risk of ever having atopic dermatitis, current food allergy, and positive skin prick test (SPT) to common aeroallergens. Sibship size of 2 or more vs having only 1 sibling was also associated with a decreased risk of current atopic dermatitis, ever having atopic dermatitis, and positive SPT to common aeroallergens. However, no significant associations were found regarding atopy assessed through allergen-specific immunoglobulin E (IgE) with common allergens.

“Similar association was seen with SPT sensitization,” the authors noted, “However, significant protection was not found for IgE sensitization.”

Reference
Lisik D, Ermis SSÖ, Ioannidou A, et al. Birth order, sibship size, and risk of atopic dermatitis, food allergy, and atopy: a systematic review and meta-analysis. Clin Transl Allergy. 2023;13(6):e12270. doi:10.1002/clt2.12270