Early life and Adulthood Depression: Birth seasonality on demographic characteristics of depressive symptoms

Abstract

Background Environmental and biological factors in early-life in-utero can have critical health implications in adulthood. However, despite the extensive literature on the association between depressive symptoms and female gender, higher age, lower education, and lower socio-economic status, no studies have thus far investigated these depression-related demographic factors in connection with early-life environment. Here, the present study aimed to explore the effects of birth seasonality on demographic characteristics of depressive symptoms in adults. Methods We employed data from the project of Chinese Labour-forces Dynamic Survey (CLDS) 2016, containing the epidemiological data of depressive symptoms with a probability proportional to size cluster and random cluster sampling method in 29 provinces of China with final sample of 16,181 participants was analysed. Logistic regression analyses were performed to test the relations between having depressive symptoms and various demographic characteristics in the overall population and different layers driven by the season of birth (Spring: March, April, and May; Summer: June, July, and August; Autumn: September, October, and November; Winter: December, January, and February). Results In line with previous studies, female gender, higher age, lower education, lower satisfaction of family income, and northern geographical region were the depressive symptoms-related factors. Season of birth did not significantly contribute to having depressive symptoms. Gender and satisfaction of family income were significant for the linear trend in people born in spring, summer, autumn, and winter. Age was significant for linear trend in people born in spring and winter. Education was only significant in spring. The categorical variable of geographical region had different associations with depressive symptoms across seasons of birth. Conclusions Our findings indicate that although season of birth is not significantly associated with depressive symptoms, it influences the effects of the demographic factors on depressive symptoms (particularly in age). The present study sheds lights on the discussion of environmental and biological effects related to season of birth on adult mental health.