Despite lengthier active resuscitation of very preterm babies over the past 15 years, their survival rates have not improved, indicates research published ahead of print in the Fetal & Neonatal Edition of Archives of Disease in Childhood.
The authors base their findings on a case note review of babies born alive after 22 or 23 completed weeks of pregnancy between 1993 and 2007, in one region in the north of England.
During the study period, there were 480,662 live births, of which 229 babies were born at 22 or 23 weeks, a time point that is considered to be at the "margins of viability."
Two hundred and 10 of these babies died, one in three (34%) of whom lived for more than six hours. The length of time they lived gradually increased between 1993 and 2007.
The average survival of those who died, but were actively resuscitated, was 11 hours in 1993 to 1997, increasing to 20 hours in 1998-2002, and 3.7 days in 2003 to 2007.
In the last five years of the trends analysis, the accompanying documentation clearly showed the types of treatment given to these very premature babies.
Forty six out of 77 babies (60%) were actively resuscitated, 43 of whom survived for at least six hours. Ten of these babies underwent surgery.
These figures indicate that babies born at 22 to 23 weeks are increasingly being actively treated and for significantly longer in intensive care, but that the outcome is still the same, say the authors.
There was little evidence that more babies survived as time went on. Among the total of 19 survivors over the study period, six survived between 1993 and 1997; six survived between 1997 and 2002; and seven survived between 2003 and 2007.
The authors point out that survival rates for babies born at 24 weeks and above have increased, and that this may be why those born under 24 weeks are increasingly being actively treated as well.
Despite guidelines, the cut off point for providing active treatment for those born under 24 weeks remains "extremely contentious," they say, and parents push for treatment.
"Our local (anecdotal) experience is that most parents request an active approach immediately after delivery at 23 weeks' gestation, despite counselling from experienced clinicians using nationally consistent survival data," say the authors.
Explore further: Study: Prematurely born babies feel pain