Season of birth

The time of a year in which a person is born has been linked to physiological and psychological changes to humans. Unlike Astrology, the scientific researches on the seasonality of births are usually trying to establish causal relationships (correlation ratios) with physical and mental health. Hippocrates recognized the importance of season of birth in 460 BC.

Description
Scientific researches in the field of seasonality of birth are one of the important and perspective concept in statistical human physiology and epidemiology. Despite the large number of works realized by research teams and individual researchers of different fields of physiology and medicine all this works trying to explain the reasons for discovered ratios of any hypothesis. It is the main cause of the impossibility of association results in a unified system of knowledge. Probably there is point to consider the results of such researches only how statistically accurate information while there is no consensus.

Influence on medical conditions
The season in which babies are born can have a dramatic effect on their future risk relating to the development of conditions such as neurological disorders, including seasonal affective disorder, bipolar depression, schizophrenia and type I diabetes. Research has shown that the season a baby is born in can have a major effect on whether or not you will become a heavy smoker or not. This even varies between men to women.

As a factor in infant grown
The season during which a birth takes place has been linked to the weight development of the infant as well as initial weight.

As a factor in academic development
There is evidence that suggests that children who are born earlier while they attend the same academic year with others, gain an advantage:
 * "In Britain the academic year begins in September, and there may be almost a year's chronological age difference between the eldest (September birthday) and youngest (August birthday) children in the same class. There is evidence that, in this context, children born in the autumn term (September to December birthdays) perform better academically, relative to their class peers, than those born in the spring term (January to April birthdays), who in turn outperform those born in the summer term (May to August birthdays)."

As a suicide risk factor
Birth rates of people who later kill themselves show disproportionate excess for April, May and June compared with the other months. Overall, the risk of suicide increases by 17% for people born in the spring–early summer compared with those born in the autumn–early winter; this risk increase was larger for women (29.6%) than for men (13.7%).

Research works in Sweden show that those who preferred hanging rather than poisoning or petrol gases were significantly more likely to be born during February–April. Maximum of the month-of-birth curve for preferring hanging was for March–April and the minimum was for September–October.