26,000 families across Wales will be asked to take part in new research to help to improve the health and treatments for children born prematurely.
The research is being carried out to discover if babies who were born prematurely - both extremely and moderately - in Wales have symptoms such as cough, wheezing, chest infections or hospital infections when compared to similarly aged children who were born on time.
A team at Cardiff University's School of Medicine will be sending questionnaires to parents with children who were born prematurely between 1st January 2003 and 31st December 2011.
The team hope their results will help guide doctors and other health workers by indicating whether children born moderately prematurely need to be closely followed up and if treatments already available should be started early, especially if the children have increased breathing symptoms.
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