THE secret of being born lucky is a summer birthday, with May babies most likely to enjoy a lifetime’s good fortune, according to a study of more than 40,000 people.

The time of year at which you are born has an enduring influence on levels of optimism and self-reported luck, according to research by British and Swedish scientists.

People with birthdays between March and August generally consider themselves much luckier than those born in the autumn and winter months between September and February, the survey conducted for the Edinburgh International Science Festival said.

May was the luckiest month in which to be born, with 50 per cent of those born then considering themselves lucky, while October was the least lucky month, with just 43 per cent claiming good fortune.

The findings add to growing evidence that the phenomenon of luck is not all down to chance, but is affected by a person’s general disposition.

Other research has shown that whether people think themselves fortunate depends less on objective success than on having a “glass half-full” or “half-empty” approach to life.

“If luck were all down to chance, we would expect to see no difference between the months,” Richard Wiseman, Professor of Psychology at the University of Hertfordshire, who led the research, said.

“What we are seeing suggests that something is influencing how people perceive their luckiness. My hypothesis is that people create their own luck by traits such as optimism, that luck is a psychological phenomenon rather than a matter of blind chance.”

The pattern of the results, with those born in spring and summer reporting themselves luckier than those born in autumn or winter, could have two potential explanations, Professor Wiseman said.

“One theory is a medical, physiological one, that the temperature at the time of birth might influence the development of the brain, particularly neurotransmitter chemicals,” he said. “The pattern is the same as that you see in the depression literature: people born in the winter are statistically more likely to suffer from depression, and we may be seeing the same effect here.”

“The other strong possibility is that mother-infant interactions are affected by seasonal factors. There is more post-natal depression in the winter, and mothers who suffer from this don’t interact with their children in the same way. It’s possible that this affects the psychological complexion of their children later in life.”

Children born in May, he said, experience the height of the summer during the first three months of life, while those born in October experience the entire winter first. This may explain why luckiness peaks and troughs in these months.

In the survey, conducted on Professor Wiseman’s website www.luckfactor.co.uk, more than 40,000 people answered a series of 13 questions measuring factors such as optimism, resilience and extraversion, giving them a “luck score” between one and five.

“May-borns” include the rugby player Jonny Wilkinson, the footballer David Beckham and the model Jordan. J. K. Rowling, the Harry Potter author, was a “summer” baby born in July. The singer Peter Andre and the presenter Vanessa Feltz were both born in February.

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