PURPOSE: No studies addressed the influence of breastfeeding on cataract formation. The objective of this study was to address the relationship between breastfeeding and maternal age-related cataract. DESIGN: A nationwide cross-sectional study. METHODS: This study analyzed data for 3821 parous women aged 50 years or above in the Korea National Health and Nutrition Examination Survey 2010-2012. Participants were aggregated into quartiles according to the number of breastfed children and duration of breastfeeding. Logistic regression analysis was used to examine the relationships between less or short duration of breastfeeding and increased risks of cataract. RESULTS: A total of 2197 women (57.5%) were classified as having 'age-related cataract. Women who breastfed 4-12 children (odds ratio [OR] = 0.56; 95% confidence interval [CI] = 0.35-0.89) had significantly lower risks for cortical cataract, compared to those who breastfed no or 1 child (P for trend across quartiles = .010). Women who breastfed for 36-60 months (OR = 0.61, 95% CI = 0.42-0.90) or 61-324 months (OR = 0.53, 95% CI = 0.33-0.83) had lower risks for cortical cataract compared to those who breastfed 16 months or less (P for trend across tertiles = .003). The population-attributable fractions of cortical cataract induced by number of children breastfed less than 3 and duration of breastfeeding less than 36 months were 9.4% (95% CI = 1.3%-17.6%) and 10.7% (95% CI = 3.0%-18.4%), respectively. CONCLUSIONS: Breastfeeding more children and long-term breastfeeding were associated with lower risk of cortical cataract formation in parous women. (C) 2018 Elsevier Inc. All rights reserved.