Hearing Mom’s Voice Boosts Language Development in Preemie Babies

Science shows that even before birth, babies are tuning into their parents’ voices. Around 24 weeks into pregnancy, a baby’s hearing begins to develop, and as the uterus expands and thins, more sounds—especially Mom’s voice—filter through. By the time full-term babies are born, they already recognize Mom’s voice and even prefer it over others. But for premature babies, that comforting soundtrack is suddenly interrupted.

Because preemies often spend weeks or months in the hospital, they hear far less of their parents’ speech than they would in utero. And since parents can’t always be at the hospital around the clock, researchers have long been interested in how increasing those moments of connection might support development in other ways.

To explore just how powerful a parent’s voice can be, Stanford researchers recently studied the effects of hearing Mom’s voice on the brain development of hospitalized preemies. The study, published in Frontiers in Human Neuroscience followed 46 babies born more than eight weeks early who were still in the hospital.

Babies could join the study once they were medically stable and had “graduated” from the NICU, but still needed hospital supervision. Half were regularly exposed to recordings of their mothers reading Paddington Bear for 2 hours and 40 minutes a day during the last few weeks of their hospital stays, while the other half had no exposure.

MRI results revealed that premature babies who heard recordings of their mothers reading to them had more mature white matter in a key language area of the brain than those who were not exposed to recordings. This increase in white matter led scientists to believe that mom’s voice may have a role in boosting speech and language development early on.

“This is the first causal evidence that a speech experience is contributing to brain development at this very young age,” said the lead author, Katherine Travis, PhD, who was an assistant professor at Stanford Medicine when the study was conducted and is now an assistant professor at Weill Cornell Medical School and Burke Neurological Institute. “This is a potentially transformative way of thinking about how to approach neonatal care for promoting better language outcomes in children born prematurely.”

While the study size was small and the babies were exposed to their mothers’ voices for a relatively short period, study co-author Melissa Scala, MD, a clinical professor of pediatrics and neonatologist at Lucile Packard Children’s Hospital Stanford, says the measurable benefits of hearing Mom’s voice are encouraging.

“I was surprised by how strong the effect was,” Travis said. “That we can detect differences in brain development this early suggests what we’re doing in the hospital matters. Speech exposure matters for brain development.”

For parents who missed talking to baby during those last few weeks of gestation or feel like they’re missing out on big first week moments, Scala hopes the study will offer some reassurance. “This is a way that — even if they can’t be there as much as they want to — the baby is still hearing them and still knows that they’re there,” she said. “And the parents are still contributing to the baby’s brain development.”