Premature infants are at risk for a variety of diseases, the investigators would like to learn more about why some premature babies are at higher risk and some are protected from these diseases.

Scientists at UC Davis and other universities have developed new ways to measure the bacteria and a large number of small molecules in specimens of infant blood, urine, stomach fluid and poop and in mother's milk. These discoveries allow us to consider questions that were impossible to answer before these new techniques were developed. One such question is whether the bacteria in the poop of a premature baby can help us predict the baby's risk for developing infection or a common and serious disease of premature infants called necrotizing enterocolitis. A second question is whether the DNA of a premature baby (obtained from saliva with a q-tip) can predict higher risk for diseases of premature babies.

Samples from eligible infants will be collected and stored for future comparisons. These samples include stool specimens from a messy diaper twice weekly, urine samples from cotton balls in the diaper once weekly, a small sample of stomach fluid once a week just prior to a feeding obtained through the feeding tube, a sample of mom's milk once a week, left-over blood from lab draws, and a sample of saliva on one occasion.

The analysis of key specimens from this cohort will allow us to study the impact of the bacteria in the intestines on outcomes like growth and common diseases of premature infants.

Inclusion Criteria:

• gestational age < 33 weeks at birth

Exclusion Criteria:

• none

All mothers in preterm labor in the labor and delivery ward for whom a consultation by the neonatology group is requested will be screened for eligibility. All premature infants admitted to the NICU will be screened for eligibility.