Child health experts are taking the unprecedented step of trying to contact 26,000 families across Wales to get a better understanding of how premature babies develop in the long term.
Dr Martin Edwards, one of those leading the study from Cardiff University, says there's been minimal research in this field: "This is an area of the Health Service that hasn't really been monitored or observed until now."
Researchers at Cardiff University are asking families in Wales, who have had babies born prematurely, for their help.
They want ask the parents if their children have had any breathing and health related problems, and also to ask about the child's developing and learning.
Researchers say this will help them to establish if children born only moderately prematurely need to be followed more closely during childhood "than has occurred until now."
In Wales, there are about 35,000 babies born each year and from these about 2,500 are born prematurely.
There has been a lot of research demonstrating the negative effects that extreme premature birth can have on the lung function of children, but there's limited data on the lung function of moderately preterm born children, especially as they grow older.
– Professor Sailesh Kotecha, Cardiff University's Department of Child Health
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.