Timing, they say, is everything, and that may be true for the question of whether the umbilical cords of premature newborns should be clamped immediately or after a 60-second delay.
A new study, reported Sunday at a meeting of the Vermont Oxford Network 2017 Annual Quality Congress, in Chicago, and online by the New England Journal of Medicine, is concluding that a delay makes no significant difference in a combined endpoint of morbidity and mortality.
But the chief author told Reuters Health in a telephone interview Sunday that a new, broader analysis of 18 trials, including this one and slated to be released by the American Journal of Obstetrics and Gynecology, shows that waiting 60 seconds is clearly beneficial.
The extensive review "will show that delayed clamping reduced the relative risk of hospital mortality by about a third," coauthor William Tarnow-Mordi, professor of neonatal medicine at the University of Sydney, in Australia, told Reuters Health by e-mail.
"The bottom line is that the totality of available evidence continues to support current professional guidelines, which recommend delayed cord clamping in preterm infants who do not need immediate resuscitation," he said.
Immediate clamping had been the norm until evidence surfaced that a delay might improve blood pressure and cut the odds of infection, blood transfusion, intraventricular haemorrhage and necrotising enterocolitis.
As a result, professional guidelines from various groups have recommended delays of up to three minutes when immediate resuscitation was unnecessary.
The new study tried to resolve the question with data from 1,566 babies born before 30 weeks' gestation. Dr Tarnow-Mordi and his colleagues found that the odds of death or major morbidity were virtually identical for newborns whose cords were clamped within 10 seconds (37.2%) and those clamped 60 seconds or more (37.0%) after delivery of a child at no more than 36 weeks' gestation.
Mortality rates were 9.0% in the immediate-clamping group and 6.4% in the delayed-clamping group - but the benefit of delayed clamping was not statistically significant, and the authors calculated that 11,000 births would need to be studied to properly assess a mortality difference.
"The simplest explanation is if you just let babies start to breathe by themselves, and most of them do start breathing within the first minute, they're much less at risk of having complications," Dr Tarnow-Mordisaid. "If you routinely intubate a baby that doesn't really need it, maybe you're introducing a lot of potential complications that baby would have avoided if you simply waited a minute."
"Maybe we have been too quick to intervene in these very tiny, fragile babies without giving them enough time to breathe naturally," hei added. "More and more neonatologists and obstetricians are coming around to this view, that if the baby isn't actually in extremis, there isn't a lot to be gained by immediately starting to intervene. The big controversy is - what does ‘in extremis’ look like?"