Waiting for two minutes or longer to clamp the umbilical cord of a premature baby soon after birth could help reduce the risk of death, compared with immediately clamping the umbilical cord, or waiting a shorter time before doing so. Delaying clamping could decrease the child's risk of death by more than half relative to immediate clamping.
The new findings, published today in two companion papers in The Lancet, examined clinical trial data and outcomes of thousands of premature babies which had delayed cord clamping compared to those whose cord was clamped immediately after birth.
Delaying clamping of the umbilical cord allows blood to flow from the placenta to the baby whilst the baby's lungs fill with air. This is thought to help ease the transition to breathing in the infant.
"Worldwide, almost 13 million babies are born prematurely each year and, sadly, close to 1 million die shortly after birth. Our new findings are the best evidence to date that waiting to clamp the umbilical cord can help save the lives of some premature babies," says first author Dr Anna Lene Seidler at the NHMRC Clinical Trials Centre, University of Sydney.
"We are already working with international guideline developers to make sure these results are reflected in updated guidelines and clinical practice in the near future."
Delayed cord clamping is now recommended routine practice for babies born at full term. However, whilst previous research , including trials led by University of Sydney, showed potential benefit for premature babies, best practice for this vulnerable group remained uncertain. Until recently, clinicians generally cut the cord of preterm babies immediately so urgent medical care could be given.
These uncertainties have led to different recommendations in national and international guidelines.
For instance, for preterm infants not requiring resuscitation at birth, the Australian and New Zealand Committee on Resuscitation (ANZCOR) suggest delaying cord clamping for at least 30 seconds.
The World Health Organization and the UK's National Institute for Health and Care Excellence (NICE) recommend delayed umbilical cord clamping (not earlier than 1 min after birth) for improved maternal and infant health and nutrition outcomes.
For preterm babies requiring resuscitation, the WHO recommends immediate clamping, while ANZCOR make no recommendation due to insufficient evidence.
Largest delayed cord clamping dataset to date
The studies were the result of a massive global effort (the iCOMP collaboration) among more than 100 international researchers on umbilical cord management, who shared their original data with Dr Seidler and her team for analysis, including the large APTS trial led out of the University of Sydney.
This created one of the largest databases in this research field, with over 60 studies and including more than 9000 babies.
The first paper using data from 3,292 infants across 20 studies found delayed clamping of the umbilical cord, clamped 30 seconds or more after birth, likely reduced the risk of death in premature babies by a third compared to those whose umbilical cord was clamped immediately after birth.
In a subgroup of premature babies where infants were born before 32 weeks of pregnancy, 44.9 percent of the babies with immediate cord clamping experienced hypothermia after birth, compared to 51.2 percent of those with delayed clamping. The average difference in temperature between the deferred clamping group and the immediate clamping group was -0.13 °C.
"Our findings highlight that particular care should be taken to keep premature babies warm when deferring umbilical cord clamping. This could be done by drying and wrapping the baby with the cord intact, and then by placing the dry baby directly on the mother's bare chest under a blanket, or using bedside warming trollies," says Prof Lisa Askie, senior author of the study from the NHMRC Clinical Trials Centre.
The second paper analysed data from 47 clinical trials, which involved 6,094 babies, and found waiting at least two minutes before clamping the cord of a premature baby may reduce the risk of death compared with waiting less time to clamp the cord.
In comparing different timings, waiting two or more minutes to clamp the cord had a 91 percent probability of being the best treatment to prevent death shortly after birth.
Immediate clamping had a very low (
"Until recently, it was standard practice to clamp the umbilical cord immediately after birth for premature babies so they could be dried, wrapped, and if necessary, resuscitated with ease," says Dr Sol Libesman, lead statistician for this study and research fellow at the NHMRC Clinical Trials Centre.
"Our study shows that there is no longer a case for immediate clamping and, instead, presently available evidence suggests that deferring cord clamping for at least two minutes is likely the best cord management strategy to reduce the risk of premature babies dying shortly after birth."
However, the researchers highlight situations where more research is needed on cord clamping. This includes when there are babies requiring immediate resuscitation, unless the hospital is able to provide safe initial breathing help with the cord intact, or in a low-income setting with limited medical resources.
"We need further research into how to best provide immediate care to the sickest premature babies while the cord is intact. Even for healthier premature babies, it may seem counter-intuitive to some doctors to defer cord clamping when the baby requires care, but with appropriate training and equipment, along with a full team approach involving midwives, doctors and parents, it is possible to successfully defer cord clamping whilst ensuring the baby is warm, breathing, and cared for," says Dr Seidler.
