Babies born in the spring are more prone to developing anorexia nervosa, according to a new study by Oxford University in England. Researchers discovered an excess of anorexics with birthdays between March and June, and a deficit from September to October.
The team, led by doctoral student Lahiru Handunnetthi of the Wellcome Trust Centre for Human Genetics at Oxford University, said their study — the largest to date — provides “clear evidence” of a birth-season effect in anorexia. The scientists compared the birth dates of 1,293 patients with anorexia to those in the general population.
“We meta-analyzed four cohorts of anorexia nervosa patients from the UK, making this the largest-ever study to assess the presence of a season-of-birth effect in anorexia,” said Handunnetthi.
“We found that susceptibility to anorexia nervosa is significantly influenced by a person’s season of birth, being higher in those people born in the spring and lower in those born in the autumn.”
Environmental factors around the time of conception or when the baby is developing in the womb may be responsible, the scientists suggested.
“Seasonal changes in temperature, sunlight exposure and vitamin D levels, maternal nutrition and exposure to infections are all possible risk factors. Identifying these risk factors is important in helping us understand and maybe even prevent illness in future,” Handunnetthi said.
Prior research has suggested a link between season of birth and eating disorders; however, these studies included far fewer patients and were unable to reach statistical significance.
“A number of previous studies have found that mental illnesses such as schizophrenia, bipolar disorder and major depression are more common among those born in the spring — so this finding in anorexia is perhaps not surprising,” said Handunnetthi.
“However, our study only provides evidence of an association. Now we need more research to identify which factors are putting people at particular risk,” he added.
Source: University of Oxford