Birth Month and Prevalence of Atopic Dermatitis in Children Under 3 Years in Antananarivo, Madagascar

Background: Several studies have been done to evaluate the relationship between month of birth and atopic diseases but the results are contradictory. Objective: We aim to evaluate the correlation between the month of birth and the prevalence of AD in Malagasy children less than 3 years. Methods: A case-control study was conducted based on patients' data of the department of Dermatology in the University Hospital Joseph Raseta Befelatanana (UH/JRB) Antananarivo. It included 438 children less than 3 years seen in this department between January 2010 and December 2019. For each atopic dermatitis (AD) patient, two age-and sex-matched controls without a history of AD were selected from the same period. Results: This study included 146 AD cases and 292 non-AD controls. Our case-control study found that there is a statistically significant correlation between birth month and risk of AD in Malagasy children <3 years. Compared with people born in December, people born in April had the highest risk of AD (OR: 2.11, 95% CI 0.93-4.78), followed by people born in March (OR: 1.52, 95% CI 0.79-2,88). Asthma, allergic rhinitis and allergic conjunctivitis were significantly correlated with AD in our patients. Conclusion: Our case-control study found that being born in April and March (dry season) may be associated with an increased risk of AD.