The purpose of this study was to compare the prevalence of breastfeeding in women with anorexia nervosa, bulimia nervosa, binge eating disorder and eating disorders not otherwise specified - purging subtype, with mothers with no eating disorders during the first 6 months after birth. The study is based on the Norwegian Mother and Child Cohort Study conducted at the Norwegian Institute of Public Health. Questionnaire-based information on eating disorder diagnoses and breastfeeding in 39 355 women was used to estimate the risk of cessation of breastfeeding with Cox proportional hazards regression. Almost all women (98%) initially breastfeed their infants, with no statistically significant difference between the eating disorders subgroups and women with no eating disorders. However, the risk of early cessation before 6 months post-partum increased for all subgroups of mothers with eating disorders, compared with mothers with no eating disorders. After adjusting for maternal body mass index, age, education, birthweight and pre-term birth, only mothers with anorexia nervosa [hazard ratios (HR), 2.35; 95% confidence interval (CI) 1.22-4.53] and eating disorder not otherwise specified-purging subtype (HR, 1.95; 95% CI 1.08-3.53) had increased risk for cessation of breastfeeding There were no differences in the risk of cessation of exclusive breastfeeding. These results show that some eating disorders may influence mothers' early feeding practices and indicate that additional support may be necessary to assist women with anorexia nervosa in maintaining breastfeeding.