Maternal voice reduces pain in premmies
Researchers from the University of Geneva (UNIGE), in collaboration with Italy’s Parini Hospital and University of Aosta Valley, have shown that the maternal voice reduces signs of pain in premature babies when they undergo life-saving medical interventions.
Their results, published in the journal Scientific Reports, demonstrate the importance of parental presence with premature babies, who are subjected to intense stress from birth.
As soon as they are born before 37 weeks of gestation, premature babies are separated from their parents and placed in an incubator, often in intensive care. They have to undergo daily medical interventions, necessary to keep them alive, which have potential impacts on their development and pain management. Unfortunately, it is not always possible to relieve them with pharmaceutical painkillers, as the short- and long-term side effects on their neurological development can be significant.
There are other ways to relieve the baby, such as wrapping, restraint, sugar solutions or non-nutritive sucking with a teat. However, for several years now, studies have shown that the presence of a mother or father has a real calming effect on the child, particularly through the emotional modulations of the voice. This is why the team of UNIGE Professor Didier Grandjean has been interested in early vocal contact between the mother and the premature baby, the impact of the mother’s voice on the management of pain resulting from the routine practices necessary for the follow-up of the babies, and the psychological and cerebral mechanisms that would be involved.
To test this hypothesis, the scientists followed 20 premature babies at the Parini Hospital and asked the mother to be present during the daily blood test, which is done by extracting a few drops of blood from the heel. As explained by first author Dr Manuela Filippa, a researcher in Prof Grandjean’s group, “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.”
The study was conducted in three phases over three days: a first injection was taken without the mother being present, a second with the mother talking to the baby and a third with the mother singing to the baby. The order of these conditions changed randomly. “For the study, the mother started talking or singing five minutes before the injection, during the injection and after the procedure,” Dr Filippa said.
First, the research team observed whether the baby’s pain decreased in the presence of the mother. To do this, they used the Premature Infant Pain Profile (PIPP), which establishes a coding grid between 0 and 21 for facial expressions and physiological parameters (heartbeat, oxygenation) attesting to the baby’s painful feelings. The results were significant: the PIPP was 4.5 when the mother was absent and dropped to 3 when the mother talks to her baby.
“When the mother sings, the PIPP is 3.8,” Prof Grandjean said. “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.”
The scientists then looked at what changes in the baby when it hears its mother speak, with Dr Filippa stating, “We quickly turned to oxytocin, the so-called attachment hormone, which previous studies have already linked to stress, separation from attachment figures and pain.” Using a saliva sample before the mother spoke or sang and after the heel prick, the research team found that oxytocin levels rose from 0.8 picograms per millilitre to 1.4 when the mother spoke — a significant increase, according to Dr Filippa.
These results show the positive impact of the mother’s presence when premature babies undergo painful medical procedures, and demonstrate the importance of bringing parents and children together — especially in the delicate context of intensive care, Dr Filippa said.
“Furthermore,” Prof Grandjean concluded, “parents play a protective role here and can act and feel involved in helping their child to be as well as possible, which strengthens the essential attachment bonds that are taken for granted in a full-term birth.”
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