Abstract Aims To identify maternal food‐avoidance diets and dietary supplement use during breastfeeding, and to explore factors associated with food avoidance diets. Design A prospective mother–child birth cohort study. Methods Electronic questionnaires were answered by 1,462 breastfeeding mothers 6 months postpartum in the Preventing Atopic Dermatitis and Allergies in Children (PreventADALL) study from 2014–2016. Demographic and antenatal factors were analysed for associations with food avoidance diets in 1,368 women by multiple logistic regression. Results Overall, 289 breastfeeding women (19.8%) avoided at least one food item in their diet, most commonly cow's milk in 99 women (6.8%). Foods were most often avoided due to conditions in the child, maternal factors or lifestyle choice. The odds for food avoidance diets were 2.1 (95% CI: 1.3, 3.4) for food allergy (presumed or diagnosed) and 19.4 (5.4, 70.1) for celiac disease in the mother. Dietary supplements were reported by nearly 80%, most commonly cod liver oil.
