Clinical Research Directory

Inclusion Criteria: * Healthy full-term infants (gestational age 37-42 weeks). * Age 12-18 months (inclusive). * Weight below the 75th percentile according to the "Growth Reference Standards for Chinese Children Under 7 Years Old". * Has started or plans to start stage 3 formula feeding before enrollment. * Guardian voluntarily signs written informed consent and is able to comply with all study procedures including regular visits, intervention plan, and laboratory tests. Exclusion Criteria: * Known allergy to milk protein or the study formula. * Known allergic constitution or high allergy risk (parent with allergic constitution). * Malnutrition assessed by investigator. * Chronic infectious disease, metabolic disease, genetic disease, or any other condition affecting feeding or growth and development. * History of preterm birth or admission to Neonatal Intensive Care Unit (NICU), excluding phototherapy for jaundice. * Severe constipation or diagnosis of other functional gastrointestinal disorders. * Cognitive or developmental disorders. * Any other condition that, in the investigator's judgment, makes the infant unsuitable for participation.