It's something mamas everywhere have innately understood from the beginning of time: Speaking to your baby
can help soothe them.
But new research shows just how powerfully calming a mother's voice can be.
A study out of the University of Geneva found that when mothers spoke to their premature infants during routine medical procedures, the babies' pain signs decreased—and their levels of oxytocin (the feel-good hormone) increased—all because they heard their mama's voice.
When babies are born prior to 37 weeks' gestation, they're often immediately whisked away to the neonatal intensive care unit (NICU) for monitoring, medical support and testing. These premature babies must undergo a slew of stressful medical procedures, ranging from blood tests to feeding tubes to intubation. And while researchers know this separation can be profoundly impactful on the infant
, the separation can also be difficult for the birthing parents, who aren't able to savor that precious bonding time with their baby immediately after birth. It's hard for everyone involved
But having the ability to speak soothing words to your infant while they're undergoing a painful procedure can help both mama and baby feel more connected—and can ease the infant's pain.
Talking and singing during heel pricks
The study's authors looked at pain profiles and oxytocin levels of 20 preterm infants and assessed how those metrics changed during routine daily heel prick procedures for blood collection. They then analyzed three versions of the intervention: performing the procedure the first time without the mother present, a second time with the mother talking to the baby and a third time with the mother singing to the baby. The mother was asked to start talking or singing 5 minutes before the heel prick, during the procedure and after the procedure was over.
"We focused this study on the maternal voice, because in the first days of life it is more difficult for the father to be present, due to working conditions that do not always allow days off," says Dr. Manuela Filippa, first author of the study, to ScienceDaily
. However, other researchers
have examined the effects of the father's voice on NICU babies: finding it has a calming effect, as well.
A mother's voice decreases infant pain
Infants' pain expressions decreased as a result of hearing their mothers talking to them—even more so than hearing their mothers sing. The researchers used a coding grid known as the Preterm Infant Pain Profile (PIPP) to score the infants' facial expressions and biological metrics of pain, like heartbeat and oxygen levels, from 0 to 21.
When a mother was absent from the procedure, the PIPP scores were 4.5. When a mother sang to her baby, the scores were 3.8. But when a mother talked to her baby, the score dropped down to 3.
"This difference with the spoken voice can be explained by the fact that the mother adapts her vocal intonations less to what she perceives in her baby when she sings, because she is in a way constrained by the melodic structure, which is not the case when she speaks," says Didier Grandjean, full professor at the Psychology Section of the Faculty of Psychology and Educational Sciences and at the Swiss Center for Affective Sciences of the University of Geneva, in ScienceDaily.
A mother's voice increases oxytocin levels
The researchers also noticed that oxytocin levels taken from the babies' saliva samples increased when their mothers spoke to them. Oxytocin, often referred to as the cuddle hormone, can be released during skin to skin contact or breastfeeding, but also through vocalizations. Oxytocin is correlated with positive effects on social behaviors, pain, stress due to separation, and anxiety, note the study's authors. Even if traditional bonding can't take place after birth, this emotional attachment can still form through a parent's presence in the NICU.
Parental presence in the NICU is good for both babies and parents
The results from this study are incredibly validating for parents who are navigating the protocols of the NICU and new parenthood at the same time. Just being there matters. "We demonstrate here the importance of bringing parents and child together, especially in the delicate context of intensive care," says Dr. Filippa. No parent wants to helplessly watch their baby writhe in pain while undergoing a medical procedure—and these study results show not only the positive impact of maternal voice specifically but give mothers and fathers a purposeful role in helping their child feel safe, soothed and protected.
Filippa M, Monaci MG, Spagnuolo C, et al. Maternal speech decreases pain scores and increases oxytocin levels in preterm infants during painful procedures
. Sci Rep
11, 17301 (2021). https://doi.org/10.1038/s41598-021-96840-4
Flacking R, Lehtonen L, Thomson G, et al. Closeness and separation in neonatal intensive care
. Acta Paediatr
. 2012;101(10):1032-1037. doi:10.1111/j.1651-2227.2012.02787.x
Saliba S, Gratier M, Filippa M, Devouche E, Esseily R. Fathers' and mothers' infant directed speech influences preterm infant behavioral state in the NICU
. Journal of Nonverbal Behavior
. 2020 Dec;44(4):437-51.