# Investigating the association between season of birth and symptoms of depression and anxiety in adults

## TL;DR

This study explores how the season of birth might affect depression and anxiety symptoms in adults, finding a possible link for males born in summer.

## Contribution

The study provides new evidence on the sex-specific association between season of birth and depression symptoms in adults.

## Key findings

- Males born in summer had a higher risk of depression symptoms.
- No association was found between season of birth and anxiety symptoms.
- Mental health conditions were common, with 84% and 66% of participants showing depression and anxiety symptoms, respectively.

## Abstract

The season of birth exposes a fetus to varying environmental and developmental conditions which may influence health outcomes after birth. The influence of season of birth has been observed in neuropsychiatric disorders and chronic health conditions. However, research on the association between season of birth and common mental health disorders is currently limited. This global study sought to fill this gap by investigating the association between season of birth and symptoms of depression and anxiety in adults using a survey-based cross-sectional research design. Participants for this study (n = 303) were primarily women (65%) with a mean age of 26 years old. Season of birth was assessed as Winter, Spring, Summer or Fall based on birth month. Depression symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9) and anxiety symptoms were assessed using the Generalized Anxiety Disorder-7 (GAD-7) scale. A generalised linear mixed model was used to assess the association of season of birth with symptoms of depression and anxiety, by sex, controlling for age, income, and latitude differences. Mental health conditions were common among participants, with 84% and 66% of participants experiencing symptoms of depression and anxiety, respectively. Season of birth was not associated with anxiety symptoms However, while males born during summer had a higher risk of developing depression symptoms, there was no observed association among females. This study provided further evidence supporting the association between season of birth and emergence of adulthood depression symptoms, particularly in relation to sex. Future studies should investigate the biological sex-specific mechanisms that underlie mental health outcomes in relation to the developmental conditions experienced at different times of the year.