The influence of the preterm gut microbiota in health and disease has been well established. However, relatively little is known about how the microbiome changes after discharge and its relationship with growth, health and disease outcomes in the preterm population. This study aims to follow a cohort of preterm infants and explore the relationship of the later microbiome ('after discharge') with later growth and health outcomes in infancy. The study will also explore the effect of timing of stopping routinely administered probiotics on the post-discharge microbiome, infant feeding and outcomes such as colic.

The investigators aim to longitudinally follow 40 infants born before 32 weeks gestation who have also taken part in the investigators microbiome study during their NICU stay (SERVIS REC No: 10/H0908/39) and where microbiomic sampling has been adequately achieved. The investigators will collect stool at and beyond the time of anticipated discharge (beyond 34 weeks) targeted to include pre- and post-weaning, and again at a year. Actual discharge timing of these infants varies, and is usually latest in the most immature infants, allowing an assessment of the influence of physical location (NICU vs home) as well as increasing age. Using 16S ribosomal RNA amplicon analysis, the investigators will assess bacterial colonisation of the gut and measure infant weight, length and head circumference at each time point. The investigators will use a parent questionnaire to assess daily crying time, parents' perceptions of colic severity using a visual analogue scale as well as vomiting and constipation for the two weeks before sampling.

Inclusion Criteria:

• <32 weeks Corrected Gestation
• Followed up in Newcastle Region

Exclusion Criteria:

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