Randomized, controlled study consisting of three parallel arms to investigate the effects of novel infant formula on growth, gut health, immune function, and sleep status in healthy infants and young children aged 12-18 months.

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.