Purpose: To verify the anatomophysiological, psychological, and sociocultural factors of the mother-newborn binomial, as well as their association with the initiation of breastfeeding. Methods: Cross-sectional study conducted in a maternity hospital in Lima, Peru. The sample consisted of 304 healthy neonates and their mothers. Breastfeeding performance was estimated by clinical assessment using the Clinical Evaluation of Breastfeeding Efficacy scale and maternal self-perception by the Breastfeeding Self-Efficacy Scale. Multivariate Prevalence Ratios (PR) were estimated by Poisson Regression with Robust Variance and 95% confidence intervals (CI). Results: The prevalence of clinical low breastfeeding performance was 27.6%. Primiparous women were associated with higher prevalence of low performance when they did not trust to succeed [PR:2.02(95%CI:1.18-3.44)] and lower prevalence in having a good latch [PR:0.52(95%CI:0.29-0.95)], as well as in coping successfully [PR:0.59(95%CI:0.37-0.91)]. Multiparous women showed higher prevalence when they were not confident in staying motivated [PR:3.47(95%CI:1.67-7.22)] and in calming the neonate [PR:4.07(95%CI:1.83-9.95)]. There was lower prevalence in keeping the neonate awake [PR:0.32(95%CI:0.14-0.75)] and when they did not feel confident in the presence of their family [PR:0.29(95%CI:0.13-0.64)]. Conclusion: It is important that health professionals be aware of emotional, social, and cultural issues to promote quality breastfeeding.