Birth weight and atopic dermatitis: systematic review and meta-analyis.

Several studies examined the relationship between birth weight and atopic diseases, but no consensus has yet been reached regarding the results. The purpose of this paper was to perform a meta-analysis of the existing studies regarding the role of birth weight in the occurrence of atopic dermatitis. We carried out an extensive search in the international databases (Pubmed, Cochrane Library, and Web of Knowledge). We selected the cross-sectional, case-control, and cohort studies which analyzed the role of birth weight in the occurrence of atopic dermatitis. We performed a meta-analysis of the selected studies, and calculated the odds ratio (OR) and corresponding 95% confidence intervals (95% CI). We included 10 studies in the final meta-analysis, which comprised 110974 patients. Weight classification was in compliance with Pediatric Nutrition Surveillance System (PedNSS) Health Indicators. In the first meta-analysis, we selected patients with low weight (below 2500 g) and atopic dermatitis and compared them with those with normal weight (2500 - 4000 g) and atopic dermatitis. The analysis showed that low birth weight represents a protective factor in the occurrence of atopic dermatitis (OR = 0.68, CI: 0.63 - 0.75, P<0.0001). In the second meta-analysis, we compared patients with high weight (over 4000 g) and atopic dermatitis with those with normal weight and atopic dermatitis. The results indicated that increased birth weight represents a risk factor for atopic dermatitis (OR = 1.1; CI: 1.02 - 1.17; P = 0.01) Thus, low birth weight represents a protective factor for the occurrence of atopic dermatitis and high birth weight represents a risk factor for the occurrence of this disease.