Breastfeeding Duration and Anogenital Distance in 2-Year-Old Infants

Background: The anogenital distance (AGD) is an anthropometric marker determined by exposures to androgens in utero and throughout the first few months of life. Early exposures to endocrine-disrupting chemicals such as phthalates have been significantly associated with shortened AGD in boys. Limited studies have explored phthalate concentrations in breast milk and infant formula. Objective: To explore the associations between breastfeeding duration and AGD measures in infants. Materials and Methods: MALAMA (Medio Ambiente y Lactancia Materna) is a follow-up study of 430 mother-child pairs, from birth to 2 years, from two population-based cohorts in Murcia, Spain. Data were collected through medical visits and telephone surveys from birth to 2 years of age. World Health Organization breastfeeding definitions were used. AGD measurements were assessed in a subsample of 71 boys and 49 girls at the 2-year visit. Descriptive analyses, Pearson correlations, and linear regressions were calculated between AGD and breastfeeding duration. Results: Duration of all types of breastfeeding, especially full breastfeeding (FB), is correlated with AGD measures in boys (p < 0.05). AGD(AS) (anoscrotal distance) and AGD(AP) (anopenile distance) were positively associated with FB (beta = 0.004, 95%CI: 0.001-0.007 and beta = 0.003, 95%CI: 0.000-0.007, respectively). Conclusions: A positive correlation between AGD in male infants and the duration of breastfeeding is reported. Inversely, early introduction of infant formula could lead to the reduction of AGD in boys.