Did Mary Poppins have it all wrong when she advised sugar to help the medicine go down? Doctors in England suspect she may have, at least when it comes to newborns.

A new study suggests that giving a small amount of sugar solution to newborns to help relieve pain from needle pricks does nothing to stop the pain.

Infants are routinely given tiny amounts of sugar in hospitals around the world. The thinking had been that because the baby's facial expressions changed after they were given the sugar, from puckered-up to relaxed, the sugar was at least distracting the babies from their pain, if not relieving it altogether.

Many previous studies have found that the practice works, including a review of all the existing medical literature on the subject, conducted by the influential Cochrane Review.

But the new study, published in The Lancet, says those studies were flawed because they measured facial expressions rather than pain receptors.

Dr. Rebeccah Slater of University College London and colleagues pricked the heels of 59 newborns -- a procedure that was required anyway to draw a blood sample -- and monitored pain activity in the brain and spine, using a neonatal electroencephalography (EEG) cap on their heads, and spinal reflexes activity recorded with electromyography (EMG).

Half the babies were given either sterile water or a tiny amount of sucrose solution, on their tongues about two minutes before the heel lance.

They found that although the babies given the sugar water didn't wince as much, pain activity did not differ significantly between the two groups. The babies' leg reflexes also indicated they still felt pain despite receiving the sugar.

While it may seem safe enough to give babies a tiny amount of sugar, some babies who need lots of medical treatment in the early weeks of their lives may receive many doses of sugar.

She notes that it's not clear whether it's safe for babies to have multiple doses of sugar, and therefore advises that the practice of offering sugar water be stopped.

"This notion is especially important in view of the increasing evidence for short-term and long-term adverse effects of infant pain experience on neurodevelopment," the authors wrote

"The absence of evidence for an analgesic action of sucrose in this study, together with uncertainty over the long-term benefits of repeated sucrose administration, suggest that sucrose should not be used routinely for procedural pain in infants without further investigation," Slater's team said.

Authors of an accompanying commentary in The Lancet called the findings "premature." They said the study was not set up to test for more subtle effects.

"Therefore we should not be surprised that the study failed to detect an effect of sucrose on cortical evoked responses," the commentators wrote.

They added that the "study adds an important and innovative measurement to evaluating pain management in newborn babies," but that larger studies were needed.