Primary Objective: To evaluate the capacity of Lactobacillus reuteri DSM17938 to activate NOD2 receptors in preterm infants.

Secondary Objective: To analyze the impact of Lactobacillus reuteri DSM17938 on the gut microbiome of preterm infants

This study was designed as an open-label, stratified, randomized, parallel-controlled pilot study, using gestational age as the stratification factor. Participants were stratified according to birth gestational age < 32 weeks, 32 weeks ≤ birth gestational age < 37 weeks, and simple randomization method was used in each gestational age group. All subjects were enrolled after birth/hospital admission, and the experimental group started intervention at 10-14 days after birth, and the intervention period was 14 days.

Inclusion Criteria:

1. Preterm infants with a gestational age of less than 37 weeks.
2. Birth weight of less than 2500 grams.
3. Hospitalized within 72 hours after birth.
4. Parents or legal guardians have signed an informed consent form.

Exclusion Criteria:

1. Congenital digestive tract malformations, genetic metabolic diseases, or congenital immunodeficiency diseases.
2. A history of severe asphyxia, infection, or liver and kidney dysfunction at birth/enrollment.
3. Death within 72 hours after birth.

The following study documentation will be made available for sharing: study protocol, statistical analysis plan, informed consent form, clinical study report, and analytic code.

The study data will be accessible for sharing during a specified temporal window, initiating three months after study completion and publication, with availability extending through a two-year period post-publication.

Data can be shared with researchers for scientific purposes upon application to the corresponding author. The research institution's ethics committee and data safety committee will review such requests. Data sharing will be permitted only following committee approval and after proper de-identification of patient information.

Open Label