Suicide risk linked to month of birth

LONDON - People born in spring or early summer in the Northern Hemisphere have a higher risk of committing suicide than those with birthdays in the autumn or early winter, researchers said this week.

They found that women born in April, May and June were 29.6 per cent more likely to take their own lives than women born in autumn or early winter, while men had a 13.7 per cent increased risk.

"Our results support the hypotheses that there is a seasonal effect in the monthly birth rates of people who kill themselves, and that there is a disproportionate excess of such people born between late spring and midsummer compared with the other months," Dr Emad Salib, of Liverpool University, northwest England, said in the British Journal of Psychiatry.

Salib and Mario Cortina-Borja, of University College London, analysed data on 26,915 suicides and deaths from undetermined injuries in England and Wales between 1979 and 2001. All of the people involved had been born between 1955 and 1966.

They said the influence of birth season had already been established for several illnesses, including breast and testicular cancer, coronary heart disease, brain tumours, Crohn's disease and early onset non-Hodgkin's lymphoma.

Their findings are in line with reported higher birth rates in the spring and early summer of people suffering from alcoholism and mood disorders whose suicide deaths make up about 10 per cent of the annual total in England and Wales. But Salib said the findings were not consistent, the research showing that schizophrenia - also linked to suicide risk - was associated with winter births.

The researchers suggested exposure of the fetus to factors such as maternal diet, infections, toxins, the amount of sunlight and hormones could trigger physical and psychiatric disorders, including suicide, in adulthood.

"As the baby is developing, the brain is very sensitive to any change in maternal state, like infections and even temperatures," Dr Salib told the BBC. "This can affect the way that cells in the brain are arranged.

"We are born all the same but some of us are more vulnerable than others to certain diseases. Some of us will get away with it, but some may end up falling victim to disease and committing suicide."

- REUTERS