Family Matters

Mom as Recording Star: Can Playing Maternal Voice and Heartbeat Sounds Benefit Premies?

A new study suggests that premies may miss mom's sounds by being born early

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Photodisc / Digital Vision / Getty Images

Nearly five years ago, Amir Lahav became a parent of twins born prematurely at 25 weeks. They weighed just over 1 pound each.

Welcoming two newborns into the family certainly changed his life, but as a neuroscientist, it also ended up changing the course of his research. Lahav studies how the brain processes sounds, and worked primarily with neurologically impaired adults, but with the birth of his twins, his paternal instinct kicked in. He approached the chief of newborn medicine at Brigham and Women’s Hospital in Boston, where the babies lay in incubators. “Could I put a recording of my wife['s voice] in there?” Lahav asked, convinced that hearing their mother’s soothing tones would improve the babies’ development. The answer: sure.

Using his computer, Lahav recorded his wife’s voice telling the babies they’re fighters and urging them to be strong. He also included some soothing piano music, figuring it could prove relaxing for preemies. Then he tinkered with the sound to make it resemble what a baby would hear in utero. While we hear through air, babies in the womb process sound through fluid so what passes as hearing consists of more low-frequency vibrations. (Think about slipping beneath the surface of the bath as someone talks to you, or try speaking while putting a finger in each ear.) “It’s as if babies are living in a micro-subwoofer,” explains Lahav.

The twins seemed to like the recordings, and doctors and nurses in the neonatal intensive care unit (NICU) were intrigued. Moreover, it proved therapeutic for Lahav and his wife. “It was not a controlled trial,” says Lahav, “but just a crazy father trying to do something because especially in the case of premature babies, you feel very helpless.”

Once his twins left the hospital, Lahav returned to thank the chief for letting him experiment. One thing led to another, and they found themselves in a serious conversation about prematurity and how the focus of neonatal medicine has changed from saving the lives of these babies — doctors have grown expert at keeping preemies alive — to helping them grow into healthy children. Studies have shown that premature infants are at greater risk of having low IQ and developing metabolic or chronic conditions in young adulthood that can shorten their lives. Could keeping them bathed in mom’s comforting sounds lower the incidence of some of these adverse effects on their health? Lahav wound up with a job offer to find out.

MORE: Incredibly, World’s Tiniest Preterm Babies Are Doing Just Fine

As part of that deal, the hospital built what they say is the world’s first professional recording studio in a NICU. Then they embarked on a feasibility study to determine whether babies appear to benefit from hearing their mothers’ voices piped in to their individual incubators. Babies who hear their mother’s voice and heartbeat, it turns out, are indeed less likely to stop breathing or experience a slowed heart rate, according to the research published recently in the Journal of Maternal-Fetal and Neonatal Medicine.

“The majority of babies born before 32 weeks’ gestation, even without a diagnosed brain injury, are likely to have learning, cognitive, social or sensory problems down the road,” says Lahav, who is now a pediatric researcher specializing in neonatal medicine and director of the Neonatal Research Lab at Brigham and Women’s. “That tells us that something we do is still not perfect.”

Could the lack of exposure to maternal sounds at a critical time period account at least in part for subsequent problems with language, attention deficit, learning disabilities, even autism? Lahav doesn’t think it’s far-fetched. “If a baby is in an isolated environment with only the sounds of machines and noise, it could possibly translate into problems with social behavior,” he says.

In the small study, Lahav and colleagues played recordings of moms who spoke, read or sang, to a group of 14 babies born between 26 to 32 weeks, for 45 minutes, four times a day. They found a significant reduction in  problems such as apnea, in which breathing stops occasionally for more than 20 seconds, and bradycardia, in which the heart beat slows down significantly, when babies listened to their personalized MSS, or maternal sound stimulation. Think of it like iTunes for babies.

All babies had fewer adverse episodes when exposed to maternal sounds, but the measurement was only statistically significant in babies 33 weeks or older, according to the study. That might be because by 32 weeks, the auditory brain system is more developed, and the babies are able to process the sounds better. In general, Lahav hypothesizes, babies who hear their mothers may have reduced cortisol levels, which correlate with less stress.

MORE: When It Comes to Preventing Preterm Birth, the U.S. Gets a ‘C’

Lahav is in the process of testing that theory in a more rigorous trial involving 100 babies born before 32 weeks. Half of the babies’ mothers are connecting with their inner rock star in the NICU recording studio, where they are asked to produce three types of vocalization — speaking, reading and, yes, singing. A tech also records their heartbeat, then muffles the sound to remove high-frequency pitches. The other half won’t be making recordings, and researchers are tracking a host of outcomes for babies born to both groups, including growth, weight gain, length of NICU stay, the time it takes the babies to regain their birth weight and their rate of medical complications.

As tempting and appealing as it is to try this at home, Lahav advised against it. He gets emails from all over the world asking how to replicate maternal recordings, but he notes that it’s too easy for something to go wrong: humidity can wreck an iPhone placed in an incubator or a well-intentioned nurse could accidentally jack up the volume, which could alarm the infant.

His lab is working on developing a process that would allow parents outside Boston to make a recording of Mom and send it to Brigham and Women’s, where technicians would give it the in utero sound, then return it to the sender with the appropriate equipment, including speakers, to install in an incubator.

As for Lahav’s own children, they’re healthy preschoolers who show no signs of having arrived 15 weeks before they were due. Did their mom’s encouraging words help? Did the soothing piano music make the difference? Either way, notes their dad, “they’re outstanding kids but clearly outliers in terms of the statistics.”

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