Pattern of birth in restrictive and bulimic eating disorders Eva M. Pen ˜as-Lledo ´ a, * , Laura Rodriguez Santos a , Francisco J. Vaz Leal a , Glenn Waller b a Department of Pharmacology and Psychiatry, Medical School, University of Extremadura, Avenue of Elvas s/n, 06071 Badajoz, Extremadura, Spain b Department of General Psychiatry, St. George’s Hospital Medical School, University of London, London, UK Abstract 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. D 2003 Elsevier Science Ltd. All rights reserved. Keywords: Pattern of birth; Anorexia nervosa; Bulimia nervosa 1. Introduction In the northern hemisphere, there is a tendency for eating-disordered patients to be born in the late spring and early summer, but only where the disorder has a substantial restrictive component or a restrictive history (Morgan & Lacey, 2000; Nielsen, 1992; Rezaul, Persaud, Takei, & Treasure, 1996). This pattern may be related to environmental temperature at birth 1471-0153/03/$ – see front matter D 2003 Elsevier Science Ltd. All rights reserved. PII:S1471-0153(02)00091-0 * Corresponding author. Tel.: +34-924-289456; fax: +34-924-289467. E-mail address: elledo@unex.es (E.M. Pen ˜as-Lledo ´). Eating Behaviors 3 (2003) 325 – 328