The likelihood of developing an eating disorder in adulthood may be increased by having had a complicated birth, an Italian study suggests.
What happens at birth could have long-term effects
Maternal anaemia and placental problems were among the conditions which increased a child's risk of developing anorexia nervosa, researchers found.
Other complications were linked to the development of bulimia, the Archives of General Psychiatry paper suggested.
UK experts said a maternal eating disorders could also be a factor.
Anorexia is characterised by self-starvation and weight loss, while bulimia involves food "binges" followed by purging.
Both are believed to be caused by a complex interaction between genetic and environmental factors.
Previous studies have suggested links between a lack of oxygen and nutrients in the womb and other psychiatric disorders, including schizophrenia.
University of Padua researchers studied 114 women with anorexia, 73 with bulimia, and a group of 554 of the same age (born between 1971 and 1979) who had neither condition.
The women were studied to see who had developed eating disorders, and if their births had been complicated in any way, using data from hospital records.
In the study, anorexia was also associated with heart problems, low body temperature, tremors and low response to stimuli in newborns.
Placental infarction (death of some placental tissue), poor responses, early difficulties with eating, shorter than average length at birth, and low birth weight were linked to an increased risk of bulimia nervosa.
The researchers found that the number of complications affected the age at which children developed anorexia.
When there were more than five complications, women developed the disorder at an average age of 16.3.
If there had been between one and five complications, onset of anorexia occurred at around 17.5 years.
If there were no birth complications, anorexia developed - on average - at 18.8 years of age.
The team, led by Dr Angela Favaro, writing in the Archives of General Psychiatry, said such birth complications could have an effect on the development of the child's brain.
"This type of relationship is considered evidence of a causal link and would indicate that an impairment in neurodevelopment could be implicated in the pathogenesis [disease development] of anorexia nervosa."
The researchers say they do not have information about the psychiatric history of the mothers, and therefore cannot say if they themselves experienced an eating disorder.
They add: "Although it is unlikely that the presence of psychiatric disturbances in mothers could completely explain the association between obstetric complications and the development of eating disorders, maternal psychiatric morbidity [illness] could be a confounding factor.
"However, other types of maternal factors, including the outcomes of previous pregnancies, did not seem to be associated with an increased risk of developing eating disorders."
Professor Janet Treasure, of the Institute of Psychiatry, said the findings fitted in with other research in the field.
She added: "There is evidence that stress at birth - such as that caused by these complications - sets the stress system so that the sensitivity is high."
A spokesman for the UK's Eating Disorders Association said: "This is a reasonably large study. Its findings are very interesting and deserve more study.
"And there's no question that if there are complications around birth, the child needs careful monitoring."
But he added: "Some birth complications are more likely in mothers who have anorexia or bulimia themselves."
The KCL team is part of an international study which aims to identify some of the risk factors (and also protective factors) that lead to an eating disorder.
They are appealing for people from a family where two or more have, or had, anorexia nervosa to contact them on 07914 777848 or firstname.lastname@example.org