Systematic Exploration of Birth Season-Associated Pediatric Diseases in Hangzhou, China: A Retrospective Observational Study

Background Season of birth (SOB) has been associated with various pediatric diseases, but previous studies often focus on a limited number of diseases. Therefore, this study comprehensively and systematically investigates the associations between SOBs and numerous common pediatric diseases. Methods This was a retrospective observational study of 3,480,838 children (age<18, 2014-2021) with 10,167,101 outpatient visits recorded in Hangzhou, China. Assessing associations between 1,396 common pediatric diseases (case counts >100) and SOBs by chi-square test with Bonferroni correction, odds ratios (ORs) from adjusted logistic regression models (adjusted for sex, age, and visit season) and prevalence ratios (PRs, SOB vs the other 3 SOBs). Results A total of 360 significant associations across 179 SOB-associated diseases (details at http://pedmap.nbscn.org/birth.html), including 146 novel diseases and 33 previously reported diseases, were identified. Spring births were only positively significant associated with tinea versicolor (PR=-0.54). The strongest positive association was observed between seborrhoeic infantile dermatitis and autumn births (OR=4.03, 95% CI 2.42 to 6.69; PR= 0.52). Additionally, the effects of SOBs on disease risk varied significantly between sexes, particularly for disorders of fatty-acid metabolism (boys: OR=3.01 vs girls: OR=1.98) and seborrhoeic infantile dermatitis (boys: OR=3.47 vs girls: OR=5.39) in autumn births, G6PD deficiency (boys: OR=1.69 vs girls: OR=3.15) in summer births, and all kinds of inguinal hernias in winter births. Conclusions This systematic investigation corroborated previous findings and identified novel associations between pediatric diseases and SOB. Children born in autumn and winter may be at greater risk for various diseases, with some diseases exhibiting notable sex disparities in their associations with SOBs. These insights highlight the importance of considering seasonal and sex-related factors in pediatric disease prevention and management strategies.