The aim of this study is to obtain a longitudinal view of the gut microbial establishment of a cohort of 51 preterm (PT) infants compared to 50 full-term (FT) infants from birth to 90 days of age, and to identify key clinical factors that affect the establishment of neonatal microbiome.

The hypothesis of the investigators is that the gut microbiota progression of PT group and FT group is different in diversity and composition. Antibiotics and its usage duration is likely the main factor disturbing the colonization and development of the gut microbiome of PT infants.

Premature birth is a global clinical problem. Early colonization and development of the neonatal gut microbiome is critically important with a profound impact on the host lifelong health. V3-V4 region of 16S rRNA amplicons of 581 stool DNA will be sequenced from a cohort of 51 PT infants and 50 FT infants to examine the microbial profiles. A random-effects generalized least square regression model is used to compare the difference in the main bacterial groups over time with the adjustment for multiple variables including gestational age and use of antibiotics .

Inclusion Criteria:

Preterm infants

1. gestational age <37 weeks;
2. no gastrointestinal tract disorders, metabolic diseases, or viral hepatitis;
3. hospital stay > 7 days;

Exclusion criteria:

1. NICU stay less than 7 days
2. Necrotizing enterocolitis infant

Control group:

1. Full-term healthy infants;
2. gestational age >37 weeks;
3. vaginally born;
4. no gastrointestinal tract disorders, metabolic diseases, or viral hepatitis.

About 50 preterm infants and 50 full-term healthy infants