Preemies show less pain when mom holds them than when dad tries to comfort them, according to a new study of babies having blood drawn at the hospital.
But the differences were small, said an outside researcher, and what's more important is that being held by either parent seemed to help babies get through the heel-stick procedures more easily.
Researchers investigated the effect of so-called "kangaroo care" on the babies' expressions of pain. In kangaroo care, an adult holds the infant, wearing only a diaper, against his or her bare chest, with a sheet or other cover wrapped around the pair.
"There's a big difference between when a baby gets (blood drawn) alone in an incubator and when the mom or dad holds the baby for this procedure," said Dr. Larry Gray, a pediatrician at Comer Children's Hospital at the University of Chicago who was not involved in the new study. "The first take-home is, boy, this really works."
Previous studies have shown that skin-to-skin contact has a number of positive health benefits for the baby, including relieving pain. And that could be especially important in preemies that need extra medical procedures and are more fragile than full-term babies, experts say.
"Here's a little 3-pound baby who says, 'I'd much rather have weighed 6 pounds or 7 pounds at birth, and now I have to keep myself warm, I have to beat my little heart,'" Gray said. With kangaroo care, "the parent provides the warmth, and the breathing regulation, and all of those hidden things," he told Reuters Health.
For the new study, C. Celeste Johnston from the McGill University School of Nursing in Montreal looked at 62 preemies in the neonatal intensive care unit who needed multiple heel stick procedures for blood tests. For each of those procedures, the investigators had the baby's mom and dad alternate who held the baby using kangaroo care.
At the same time, they videotaped the faces of each of the babies during and after the blood draw. The faces were then analyzed for tell-tale expressions of pain, such as squeezed eyes and a furrowed nose and lip. Pain was rated on a 0-to-21 scale.
With dads providing kangaroo care, pain scores were 8.5 and 8.6 at 30 seconds and 1 minute after blood was drawn. When babies were held instead by their moms, the scores were 1.4 to 1.5 points lower at those intervals -- but no different after 1 minute. That compares to pain scores of about 11 to 13 in other studies of babies who got a heel stick while lying in an incubator.
In general, moms reported having a bit more experience with kangaroo care than dads, although Johnston and colleagues said that didn't necessarily seem to explain the differences in babies' pain.
"This supports the hypothesis that there is something unique about the comfort of a mother's contact over and above that of another caring adult," they wrote in the Archives of Pediatrics and Adolescent Medicine. "The difference in the male physique, especially the chest, may be perceived by the infant to be not that of a natural caregiver."
Still, according to Gray, the main message is that "mothers or dads are way better than just having (a painful procedure) done with no kangaroo care, no parent contact," though "mothers who have a little experience with it can do it a little bit better than dads."
He also noted that both moms and dads in the study said they felt positively about doing kangaroo care with their babies and would do it again. Although it's a scary thing to hold a tiny vulnerable baby, he said, the new findings show it does help.
"Mothers and fathers should feel very comforted," he concluded.