Breast Versus Bottle Study

Inclusion Criteria: * Mothers 18-40 years of age * Infants 0-24 weeks of age * Infants who have not yet been introduced to complementary foods and beverages * Dyads are breast- and bottle-feeding * Mother is predominantly or solely responsible for infant feeding Exclusion Criteria: * preterm birth (i.e., gestational age \<37 weeks) * low birth weight (\<2500 g) * maternal smoking during pregnancy * current or past medical conditions that interfere with oral feeding * history of slow growth or failure to thrive * weight for length percentile \<5th * diagnosed developmental delay (e.g., Down's syndrome)