A new study has raised questions about the appropriateness of admissions to US intensive care units for newborn babies after it found the number has been rising among all birthweights.

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Regardless of birthweight, US newborns are 'increasingly likely to be admitted to an NICU.'

Published in JAMA Pediatrics, the study finds that overall admission rates to neonatal intensive care units (NICUs) in the US rose from 64.0 to 77.9 in every 1,000 live births - for all birthweight categories.

The data have been enabled by the 2003 revision to the US Standard Certificate of Live Birth, which includes a new line to show whether a newborn is admitted to the NICU.

Few studies have investigated rates of NICU admission outside births of very low-weight infants.

Since the first NICU opened 55 years ago in the US to provide highly specialized care to premature and sick infants, the neonatal mortality rate has fallen drastically - from 18.73 per 1,000 live births to 4.04 per 1,000 live births in 2012.

But the results raise questions about "possible overuse of this highly specialized and expensive care in some newborns," say the researchers.

For their study, Wade Harrison and Dr. David Goodman - of the Dartmouth Institute for Health Policy and Clinical Practice at the Geisel School of Medicine at Dartmouth in Lebanon, NH - examined data for almost 18 million live births to US residents between January 2007 and December 2012 in 38 states and the District of Columbia.

A breakdown of the overall rise in newborn admissions shows that:

  • There were 43 NICU admissions per 1,000 normal-birthweight (2,500 to 3,999 grams) infants in 2012
  • The admission rate for the same year for very low-birthweight (below 1,500 grams) infants was 844.1 per 1,000 live births
  • NICUs increasingly admitted full-term infants of higher birthweights from 2007 to 2012
  • Nearly half of all NICU admissions in 2012 were for normal-birthweight infants or for those born at 37 weeks gestation or older.

The authors conclude: "Newborns in the United States are increasingly likely to be admitted to a NICU, and these units are increasingly caring for normal-birthweight and term infants."

"The implications of these trends are not clear," they add, "but our findings raise questions about how this high-intensity resource is being used."

'Hospitals must prove NICU need'

An editorial about the study in the same issue of the journal is more forthright about the question. Dr. Aaron Carroll, of the Indiana University School of Medicine in Indianapolis, writes:

"If hospitals want to argue that NICUs are necessary, they will need to prove that the need exists, especially in light of the increasing share of infants admitted who are at or near full term."

Dr. Carroll adds: "Once again, it is critical to stress that the important work of Harrison and Goodman does not prove that the increased NICU admissions we are seeing are fraudulent or even merely wasteful."

"It is entirely possible that the admissions are justified. However, there is no doubt that they are expensive and carry potential harm," he continues.

"If hospitals are unable to demonstrate that NICUs are necessary, then it is very likely that, at some point in the near future, policies will force them to reduce those admissions, which will have major implications for NICU and hospital finances."