To evaluate the efficacy and safety of sunbathing and Bifidobacterium alone or in combination for full-term neonates with hyperbilirubinemia. The investigators hypothesize that the combination therapy of sunbathing plus Bifidobacterium is safe and effective for prevention and management of hyperbilirubinemia in full-term neonates. The investigators therefore design this prospective, randomized, controlled study to assess the preventive effects of sunbathing combined with Bifidobacterium supplementation on hyperbilirubinemia in full-term neonates. These observations may provide scientific evidence for the use of sunbathing and Bifidobacterium supplementation in the management of hyperbilirubinemia in full-term neonates.

To evaluate the efficacy and safety of sunbathing and Bifidobacterium alone or in combination for full-term neonates with hyperbilirubinemia. The investigators hypothesize that the combination therapy of sunbathing plus Bifidobacterium is safe and effective for prevention and management of hyperbilirubinemia in full-term neonates. The investigators therefore design this prospective, randomized, controlled study to assess the preventive effects of sunbathing combined with Bifidobacterium supplementation on hyperbilirubinemia in full-term neonates. A total of 200 neonates treating in Zhuhai Center for Maternal and Child Health Care from Jan. 2024 to Jun. 2024 will be randomized assigned to either trial groups (receiving sunbathing and Bifidobacterium either alone or in combination) or control group receiving traditional therapy. The primary outcome is the incidence of the hyperbilirubinemia and the secondary outcomes include the hospitalization rate, the hospital stays due to hyperbilirubinemia, and the bilirubin levels. Statistical analyses will be performed using ANOVA or chi-square tests, and further pairwise comparisons will be performed using the Bonferroni correction.

Inclusion Criteria:

• Term infants with 37 weeks ≤ gestational age < 42 weeks and 2500g ≤ birth weight < 4000g
• Age ≤24 hours
• Stable basic vital signs
• Liver and kidney function normal
• No prior use of antibiotics or ecological agents before specimen collection
• Healthy mothers during pregnancy, with no history of antibiotics or microecological agents before, during, or after childbirth
• Exclusively breastfed
• Informed consent provided voluntarily.

Exclusion Criteria:

• Gestational age <37 weeks or ≥42 weeks
• Complications present with pneumonia, septicemia, or other illness
• Severe immunodeficiency disease present
• Inherited metabolic diseases identified
• Congenital biliary malformations or other organ malformations
• Drug allergies
• History of asphyxiation
• Before enteral feeding, constipation, abdominal distension, diarrhea, vomiting or other gastrointestinal symptoms had appeared
• Enteral feeding was not performed
• Antibiotics or other microecological agents were used
• Isoimmune hemolysis, extravascular hemolysis, polycythemia, erythrocyte enzyme deficiency, erythrocyte morphological abnormality, hemoglobinopathy, etc.
• Hyperbilirubinemia were diagnosed within 24 hours of birth
• Situations that may warrant exclusion as determined by the researcher, such as a guardian with mental illness or frequent changes in living or working environments, which might result in loss of follow-up

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