Improving survival rates for extremely premature babies mean it is now possible to save the lives of babies born at 22 weeks, guidance says.
Previously it was recommended that only babies born at 23 weeks or later were given treatment to save their lives.
But there is now evidence those born earlier can survive – although only in small numbers – the British Association of Perinatal Medicine said.
It said most will die but a third may survive where treatment is possible.
Prof Dominic Wilkinson, a consultant neonatologist who helped draw up the guidance, said since the previous guidance was published, advances in treatment meant doctors were trying to save the lives of some babies born at 22 weeks.
He said evidence from those cases had convinced BAPM to update its guidance.
He said it was “fantastic news” that some babies born at such an early stage were now surviving.
But he added: “The very high risks mean it’s not always the right thing to do to provide intensive medical treatment.”
Survival for babies born before 22 weeks is not considered possible because the lungs are not developed enough.
The twins who survived at 22 weeks
Ruben and Jenson Powell became the youngest surviving pre-term twin boys born in Britain when they were born in August last year at 22 weeks and six days.
Parents Jennie and Rich, from Brighton, were in Cornwall when Mrs Powell went into labour.
They were flown to a specialist hospital in Oxford where the twins were born the next day.
“It really is a story of hope and miracles,” said Mrs Powell. “They defied every set of odds that they were given.”
Eight days after delivery, Ruben had a lifesaving operation when his intestines failed but battled through despite the low survival rate.
Jenson also suffered from weakness in his lungs but pulled through.
The twins had to have 20 blood transfusions, eye injections and laser surgery to prevent blindness and survived both blood poisoning and pneumonia.
