Associations between season of birth and the risk of lung cancer: epidemiological findings from Hungary

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.

Birth in winter can reduce the risk of lung cancer: A retrospective study of the birth season of patients with lung cancer in Beijing area, China

The season of birth is an important risk factor for several diseases. We explored the relationship between birth season and lung cancer. In this population-based retrospective study, we focused on patients with lung cancer who had registered at the Beijing Institute for Cancer Research from 2003 to 2012. In total, 33,025 patients were divided into five subgroups based on their histologic classification, and these five subgroups were compared with the general population (i.e., the permanent resident population of Beijing in 2013). A binary logistic regression method with sex and age as control factors was used to evaluate the relationship between birth season and lung cancer; P < 0.01 was statistically significant. Taking winter as a reference in our analysis of the relationship between season of birth and lung cancer, we found that people who were born in other seasons had a higher probability of developing lung cancer (spring: odds ratio [OR] = 1.06, 95% confidence interval [CI] = 1.03-1.09; summer: OR = 1.07, 95% CI = 1.04-1.10; autumn: OR = 1.06, 95% CI = 1.03-1.09) (P < 0.01). Among the five subgroups, persons with squamous cell carcinoma who were born in summer were more likely to develop lung cancer than those who were born in winter (OR = 1.09, 95% CI = 1.02-1.15, P = 0.006). The other subgroups showed no correlation with season of birth (P > 0.01). This study demonstrates that for people born in winter, the risks of developing lung cancer and squamous cell carcinoma are comparatively lower than those for people born in other seasons. Differences in immune function and the maternal nutrition status during pregnancy of people born in different seasons may explain this finding.

Understanding the links between month of birth, body height, and longevity: why some studies reveal that shorter people live longer – further evidence of seasonal programming from the Polish population

There is a lack of agreement in the literature as to whether adult height depends on month of birth and whether height affects lifespan. Additionally, the relationship between stature and longevity involves conflicting findings and the results remain mixed due to several confounders, such as: year of birth, somatotype, relative body weight, genetic inheritance, diet, diseases, etc. Here, we hypothesize that the season of birth effect can also be involved in shaping the mysterious link between body height and longevity. To assess the links between month of birth, adult height, and longevity in the Polish population, data on 848,860 individuals, of whom 483,512 were men (57%) and 365,348 were women (43%), born in the years 1896-1988 and died in the years 2004-2008, were collected from the ‘PESEL’ database and signalments in the censuses obtained from identity card offices throughout Poland. ANOVA and the LSD test were performed. A significant relationship between month of birth and lifespan was found. Individuals born in autumn and winter months lived significantly longer than those who were born in the middle of the year (May). The amplitudes of lifespan were 16 months in men and 14 months in women. As expected, subjects of both sexes born in autumn and winter months were significantly shorter than their peers born around the middle of the year. In conclusion, the results of the study not only corroborate the theory of seasonal programming of longevity and support the idea that some undetermined factors from early stages of ontogeny and associated with season of birth have long-term effects on phenotype in later life in terms of adult height and longevity, but also bear out the hypothesis that month of birth can be another important confounding factor with respect to the relationship between adult height and longevity.