The influence of birth month on total and cardiovascular mortality: a population-based surveillance study

There is little evidence about the impact of birth month on total and cardiovascular disease mortality in developing countries. We evaluated these associations using the population health registration data of Hefei City, China from 2014 to 2017. After controlling for the fixed effects of gender, education, and occupation, we fitted the Cox proportional hazard regression model to assess the relationship between birth month and mortality. Hazard ratio (HR) with corresponding 95% confidence interval (CI) was calculated. All data analyses were performed by R 3.6.0 software. The data of 44 665 participants were analyzed in the study. Compared to people born in January, people born between May and October had higher total and cardiovascular mortality, being highest in June, respectively, HR: 1.130 (95%CI: 1.074 to 1.190) and HR: 1.200 (95%CI: 1.115 to 1.290). After stratification by gender, males born in June had highest risk total and cardiovascular mortality, with an increase in risk of 14.8% and 24.7%, respectively. For females, highest risk of total mortality was increased by 11.1% in those born in July, while those born in December had highest increase in cardiovascular mortality risk by 15.7%. Our results indicate in Hefei City, China month of birth is associated with total and cardiovascular disease mortality.