Last year, almost 1.1 million of the global deaths among children under the age of 5 were a result of complications related to preterm birth, according to researchers.
The research team, led by Dr. Robert Black of the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, publish their findings in The Lancet.
According to the World Health Organization (WHO), the global mortality rate among children under the age of 5 years has reduced from 76 deaths per 1,000 live births in 2000 to 46 deaths per 1,000 live births last year, representing an annual reduction of 3.9%. During the same period, however, mortality rates from preterm births only reduced by 2%.
In this latest study, Dr. Black and his team estimated that there were around 6.3 million deaths among children under the age of 5 last year. Almost 1.1 million of these deaths were a result of complications related to preterm birth - making it the leading cause of death among young children.
In detail, the team found that 965,000 deaths in the first 28 days of an infant's life were caused by direct complications from premature birth, and such complications caused 125,000 deaths among children aged between 1 month and 5 years.
India was the country with the highest number of deaths from preterm birth complications, at 361,600, followed by Nigeria, Pakistan, Democratic Republic of Congo, China, Bangladesh, Indonesia, Ethiopia, Angola and Kenya.
Macedonia was the country with the highest percentage of deaths from preterm birth complications among under-5s, followed by Slovenia, Denmark, Serbia, UK, Hungary, Slovakia, Poland, Republic of Korea and Switzerland.
In the US, 28.1% of deaths among under-5s were a result of preterm birth complications - the equivalent to 8,100 deaths. This ranks the US at 141 out of 162 countries for the worst rates of preterm birth-related deaths.
The researchers note that among high-resource countries, the US has one of the worst preterm birth rates. According to the National Center for Health Statistics, around 11.4% of babies in the US were born prematurely last year.
Findings 'mark a turning of the tide'
In addition to preterm birth, the researchers found that pneumonia was a major cause of death among children under 5 years, killing 935,000 last year.
Childbirth complications were also responsible for 720,000 deaths in under-5s, of which 662,000 occurred within the first 28 days of life - the majority on the first day - and 58,000 occurred after this point.
Commenting on their overall findings, co-author Dr. Joy Lawn, of the London School of Hygiene and Tropical Medicine in the UK, says:
"This marks a turning of the tide, a transition from infections to neonatal conditions, especially those related to premature births, and this will require entirely different medical and public health approaches.
The success we've seen in the ongoing fight against infectious diseases demonstrates that we can also be successful if we invest in prevention and care for preterm birth."
If current trends continue, 4.4 million young children will be dying in 2030
The researchers estimate that if global death rates among children under the age of 5 continue to follow their current trends, then around 4.4 million will be dying in the year 2030.
What is more, the team estimates that 60% of deaths among children under 5 will occur in sub-Saharan Africa by 2030. Last year, the region accounted for 50% of these deaths.
"Our projection results provide concrete examples of how the distribution of child causes of deaths could look in 15-20 years to inform priority setting in the post-2015 era," the team says.
"More evidence is needed about shifts in timing, causes and places of under-5 deaths to inform child survival agendas by and beyond 2015, to end preventable child deaths in a generation and to count and account for every newborn and every child."
$250 million funding received to tackle preterm birth
Since preterm birth is now the global leading cause of death in children under 5, four new research projects - receiving a total of $250 million in funding - are now underway to better determine the underlying causes of preterm births and find ways to prevent or delay them.
One of these projects is a $75 million drive being launched by nonprofit organization the March of Dimes. The Campaign to End Premature Birth will consist of five research programs aimed at uncovering the unknown causes of preterm birth.
"The March of Dimes initiative is looking at the whole spectrum of prematurity," says Dr. Joe Leigh Simpson, senior vice president for research and global programs at the March of Dimes. "Some 200 scientists from 20 disciplines are already involved in this research effort and those numbers are expected to double by next year."
Another one of the projects - led by the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS) and receiving $20 million in funding - also aims to discover the causes of prematurity, as well as find new treatments for the condition.
Talking about the overall projects, Dr. Larry Rand, director of perinatal services as the University of California-San Francisco and co-director of the university's Preterm Birth Initiative, says:
"To be successful, this has to be a team effort. Effective collaboration will accelerate discovery, increase access to interventions that work and optimize the project's impact on rates of early preterm birth and mortality."
Medical News Today recently reported on a study claiming that mothers with rheumatoid arthritis are more likely to give birth prematurely and have babies of a low birth weight.