Playing music around newborn babies may ease the pain of routine medical procedures, suggests research published Wednesday ahead of print in the Archives of Disease in Childhood.

Neonatal units are increasingly using music to calm infants during common painful procedures, despite a lack of solid evidence that it is helpful, the study team notes.

To investigate further, Dr. Manoj Kumar and colleagues from the University of Alberta in Canada systematically reviewed nine randomized controlled trials published between 1989 and 2006 that looked at the value of "newborn music therapy." Lullabies were the most common music selection in the studies. The meta-analysis included both full-term and preterm infants.

Although they were unable to reach definitive conclusions, the researchers say they found a good deal of preliminary evidence supporting "therapeutic benefits of music."

One of the "high quality" studies reviewed found that playing music during circumcision helped lower infants' heart rate, curb pain and improve oxygen levels.

In three of the studies that looked at the painful heel prick test — a common procedure for taking a blood sample from the heel of newborn infants — there was evidence that playing music seemed to help ease infants' pain.

Other benefits of playing music also included calmer infants and parents, more rapid weight gain among preterm infants, and shorter hospital stays.

"There is preliminary evidence to suggest that music may have beneficial effects in terms of ... pain reduction during painful medical procedures," Kumar and colleagues conclude.

They emphasize, however, that more rigorous trials are needed to confirm these findings.