New research from the University of Louisville in Kentucky indicates massage therapy improves the stress response in preterm infants.

Newborn intensive care units are stressful environments for preterm infants; mechanical ventilation, medical procedures, caregiving activities and maternal separation create these stressful conditions, noted a university press release.

For this study, which was recently published in Early Human Development, University of Louisville School of Nursing researcher Sandra Smith, Ph.D., and her team at the University of Utah found massage therapy that involved moderate pressure and stroking of the soft tissues followed by flexing and extending the joints of the arms and legs increased heart rate variability (HRV) in male, but not in female preterm infants.

HRV is a measure of ANS function and development. Infants who are born at term gestation demonstrate increased HRV, but preemies typically show decreased HRV and an inability to appropriately respond to stressors.

“We were surprised to learn the differences in the impact of massage therapy on preterm boys and girls,” Smith said. “Boys who received massage therapy demonstrated increased heart rate variability, but the therapy did not seem to affect HRV in girls–perhaps there are hormonal reasons for this difference.”