• Posted October 15, 2025

Mom's Voice Boosts Baby's Speech Development In The Womb

Fetuses are eavesdropping on their mothers' conversations late in pregnancy, with her voice providing an important boost to brain pathways essential for language, a new study says.

Researchers observed this connection among a group of hospitalized premature babies who listened to recordings of their mothers reading to them, according to a report published Oct. 13 in the journal Frontiers in Human Neuroscience.

Preemies randomly selected to hear these voice recordings experienced more maturation in a key language pathway in their brains, compared to those not exposed to their mom's voice, the study found.

“This is the first causal evidence that a speech experience is contributing to brain development at this very young age,” said lead researcher Katherine Travis, an assistant professor at Weill Cornell Medical School and Burke Neurological Institute in White Plains, N.Y.

“This is a potentially transformative way of thinking about how to approach neonatal care for promoting better language outcomes in children born prematurely,” Travis added in a news release.

Fetal hearing begins to develop a little more than halfway through pregnancy, around 24 weeks into the usual 40-week gestation period, researchers said in background notes.

Late in pregnancy, fetuses are capable of eavesdropping on their mother’s conversations — that’s why at birth, full-term newborns recognize their mother’s voice and prefer the sounds of their parents’ native language to other languages, researchers said.

This means that preemies, by arriving early, are missing out on something that contributes to their brain maturation, researchers said.

Preemies often spend weeks or months in a neonatal intensive care unit (NICU), typically being sent home around their original due date. While they’re hospitalized, these newborns hear less speech from their moms than they would have if they continued developing to full term, researchers said.

To see if that hindrance to development can be avoided, researchers played recordings of mothers’ voices to about half of a group of 46 preemies who arrived more than eight weeks early.

The mothers read a chapter from a Paddington Bear story book, and the recording was played during the evening in 10-minute periods that added up to 160 minutes each night, the study said.

The randomly selected preemies were exposed to these recordings for a few weeks toward the end of their hospital stays, researchers said.

Researchers then compared MRI scans of the newborns’ brains taken as part of the usual health checks performed prior to discharge.

Results showed that preemies who heard their mothers’ voice had significantly more development in their arcuate fasciculus tract, a brain region that contains large bundles of nerve fibers that help process and understand sound.

Specifically, the babies had more development in the left arcuate fasciculus tract, which is specialized for language processing, researchers said.

“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.”

This exposure was relatively short, researcher Dr. Melissa Scala, a neonatologist at Lucile Packard Children’s Hospital Stanford, noted in a news release.

“In spite of that, we were seeing very measurable differences in their language tracts,” Scala said. “It’s powerful that something fairly small seems to make a big difference.”

Researchers next plan to test whether the benefits might extend to babies with medical complications.

They also are exploring in more detail how the voice recordings exert their effects and are creating customized plans for NICU patients to better promote brain development.

Scala hopes this will help the parents of preemies feel more empowered during their baby’s hospitalization.

“We’ll always support parents visiting and talking to their babies in person as much as they can,” Scala said, noting that in-person visits also let parents to hold their babies skin to skin, which also has been shown to boost development.

“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,” Scala said. “And the parents are still contributing to the baby’s brain development.”

More information

The American Academy of Pediatrics has more on caring for a premature baby.

SOURCE: Stanford Medicine, news release, Oct. 13, 2025