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."
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A milder feel than last night but there's wind and rain on the way, and ice will form in places too!
Public Health Wales has spoken to ITV Cymru Wales about how to safe and well during the winter months.
Paramedics are poised to deal with any emergency – but 35,000 feet in the air is the last place you'd expect to have to spring into action.