Prenatal antibiotics and atopic dermatitis among 18-month-old children in the Danish National Birth Cohort

Background: Despite extensive research, the aetiology of atopic dermatitis remains largely unknown, but reduced intestinal microbiota diversity in neonates has been linked to subsequent atopic dermatitis. Consequently, postnatal antibiotics have been proposed as a risk factor, but a potential association between prenatal antibiotics and atopic dermatitis is not well studied. Overall, the current evidence suggests a positive association between exposure to prenatal antibiotics and atopic dermatitis. Objective: To investigate the association between prenatal antibiotics and atopic dermatitis among 18-month-old children. Methods: This study conducted within the Danish National Birth Cohort included 62 560 mother-child pairs. Data on maternal prenatal antibiotics were collected in the 30th gestation week and 6 months post-partum, and offspring atopic dermatitis 18 months post-partum through telephone interviews. Antibiotic use was categorized by the timing of exposure as 1st-2nd trimester (gestation week 0-29), 3rd trimester (gestation week 30-birth), all three trimesters or none. Data were analysed by logistic regression analyses adjusting for potential confounders. Results: Exposure to antibiotics prenatally was associated with increased odds of atopic dermatitis among children born by atopic mothers but only when used in both 1st-2nd and 3rd trimester (ORadj 1.45, 95% CI: 1.19-1.76). The findings were consistent using different definitions of atopic dermatitis. Conclusions and Clinical Relevance: Prenatal exposure to antibiotics throughout pregnancy was associated with an increased risk of atopic dermatitis but only within the first 18 months of life among children born by atopic mothers. The clinical usefulness of this finding must rest on corroboration in independent data sources.