Intervention can improve survival odds
Survival chances have greatly improved for premature babies, even those born extremely early, work reveals.
About 70% of babies born alive between 22 and 26 weeks gestation in Sweden now survive past the age of one, largely thanks to medical intervention.
But the authors say their study in the Journal of the American Medical Association does not answer the bigger ethical question over intervention.
Over half of the babies that survived experienced serious health problems.
Getting the balance right is really difficult and we need to keep this under constant review
Professor Neil Marlow,
Expert in neonatal medicine
The researchers looked at all infants born before 27 weeks gestation in their country during 2004-2007.
The overall perinatal mortality or death rate was 45%, meaning over half of the 1,011 babies born survived.
Some babies died before they were born, and some during or immediately after birth.
Of the 707 live-born infants, 70% were still alive at the end of the year-long observation period of the study, which is many more than have been previously reported in studies.
Analysis revealed the risk of death around the time of birth and in the first year of life was increased in the most premature.
Knowing when to intervene
For example, only five (10%) out of 51 babies born at 22 weeks survived to a year and only one of these without any major illness.
In comparison, 53% of those born at 23 weeks and 85% of those born at 26 weeks reached their first birthday, and up to half of them without serious illness.
Medical interventions did appear to make a big difference to survival odds and probably explain why Sweden had such an impressive record.
Babies born at hospitals with the best intensive care facilities and expertise and where active treatment was given - something common-place in Sweden - were far more likely to survive.
And of the 104 deaths occurring at least 24 hours after admission to a neonatal intensive care unit, 42 (40%) involved a decision to withdraw intensive care due to anticipated poor long-term prognosis.
The researchers say this suggests non-initiation or withdrawal of intensive care for extremely premature infants "cannot be based solely on a notion of unlikely survival."
But they stress this is not to suggest that all extremely premature live-born infants should be kept alive at any cost.
Limits of viability
Lead researcher Dr Karel Marsal of Lund University Hospital said: "We do not think that intervention should be done at any cost. We do not have the final answer.
"Certainly, at 22 weeks the chance of surviving is very small, but at 23 weeks the results are much better.
"But gestational age alone is not enough to judge prognosis.
"We know from other studies that some of these premature babies might go on to have problems later in life and we will be monitoring them for this."
A UK study of premature births, called EPICure, found children born very early often had learning difficulties as well as physical problems such as cerebral palsy, blindness or deafness.
As well as the long-term outlook for the child, parental desires need to be taken into account, said Dr Marsal.
Then there are the financial implications of intervening.
Researchers at the Oxford Centre for Health Economics estimate the cost of an average preterm baby is one and a half times more than a baby born full term, which equates to extra £939m a year for the whole of the UK in terms of healthcare, education costs and parental lost earnings.
The rate of premature births has increased sharply in recent years. In 2006, 7% of all births in England were preterm - a total of almost 48,000 babies - rising to 8.6% in 2007.
Professor Neil Marlow, who has been running the EPICure studies, said: "Even with better survival rates, the rate of morbidity, meaning problems that the babies have, is still very high.
"That is why we tend to be less aggressive than in Sweden with the care we offer babies born at 23 weeks gestation and younger because we believe the risks outweigh the benefits in terms of outcomes.
"But getting the balance right is really difficult and we need to keep this under constant review."