Pattern of birth in restrictive and bulimic eating disorders

Objective: To determine whether different eating disorders are associated with being born at different points in the year. Based on previous research, it was hypothesised that being born during warm months (June–August) is likely to be associated with restrictive anorexia, rather than bulimic disorders (bulimia nervosa, binge-purge anorexia). Method: Case notes from 105 eating-disordered women were used to yield dates of birth and diagnosis. Associations were calculated between diagnostic group and birth period (month, quarter of year, high-risk quarter). Results: Restrictive anorexics were significantly more likely than the bulimics (42.6% vs. 24.1%) to be born during the warmest quarter (June–August) than during the remainder of the year. Conclusions: This preliminary study suggests that being born during warmer periods may form a small risk factor for the development of a restrictive eating disorder. Further research is suggested to test and extend the hypothesis.