Is being born in spring significantly associated with early-onset bipolar affective disorder? A case-control study

Few studies have investigated relationships between birth season and early-onset bipolar affective disorder (BAD) in young adults. In the current study, birth season was compared in patients with early-onset BAD and in sex-matched and age-matched controls. A total of 957 patients aged <25 years of age from three hospitals in the North China Plain region were enrolled in the study. Sex-matched and age-matched control group data were collected in universities and schools via questionnaires. The R*C chi-square test was used to assess distributional differences in season of birth both in the patient and control group. A binary logistic regression model adjusted for age and sex was used to evaluate associations between season of birth and BAD. Using spring as the reference season, BAD patients showed significantly lower odds ratios of being born in any other season. There were associations between birth season and early-onset BAD, and early-onset BAD patients were more likely to have been born in spring. These data have implications for future disease prevention strategies and future research.