New evidence links a mother’s voice to early language brain development in preterm infants
A pioneering Stanford Medicine-led study suggests that hearing their mother’s voice can promote the maturation of key language pathways in the brains of premature babies. The randomized trial, published online October 13 in Frontiers in Human Neuroscience, compared preterm infants who heard their mothers read to them with a control group that did not receive the recordings.
The research team found that the left arcuate fasciculus, a crucial white-matter tract involved in language processing, showed more advanced development in babies who were regularly exposed to their mothers’ voices. While the right arcuate fasciculus showed less change, the left-side improvement points to a specific neural pathway through which early speech exposure may shape language outcomes.
How the study was conducted and why it matters
The trial enrolled 46 very premature babies, born at least three weeks early, who were medically stable and transitioning from the neonatal intensive care unit to intermediate care. Each mother recorded herself reading a chapter of Paddington Bear in her native language. These recordings were played to the baby during nighttime hours in 10-minute sessions, totaling 160 minutes per day, for several weeks.
To ensure objectivity, families and clinicians were kept unaware of group assignments during the intervention. MRI scans conducted as part of routine discharge assessments revealed a notable difference: the left arcuate fasciculus matured more in the treatment group compared with controls. Researchers observed that the intervention did not disrupt sleep, and the natural nocturnal listening pattern mirrored prenatal exposure when the womb naturally conveys speech sounds to the baby.
Key takeaways from the researchers
Lead author Katherine Travis, PhD, who contributed to the study while at Stanford and later joined Weill Cornell Medical College, emphasized the significance of the findings: “This is the first causal evidence that a speech experience is contributing to brain development at this very young age.” She added that the intervention could transform neonatal care strategies aimed at improving later language outcomes for children born prematurely.
Senior author Heidi Feldman, MD, PhD, noted that even a relatively brief, targeted exposure could yield measurable brain differences. “The 46 babies showed meaningful changes in their language tracts despite the short duration of the intervention,” she said. Co-author Melissa Scala, MD, highlighted the broader implications for parents navigating the stress of a NICU stay: voice recordings can supplement in-person bonding to support brain development.
From womb to nursery: the science behind early hearing
Fetal hearing begins around 24 weeks of gestation, with the uterus naturally filtering and transmitting speech as the pregnancy progresses. By birth, many full-term babies recognize their mother’s voice and prefer native-language sounds. The study leverages this prenatal window, suggesting that artificially replicating in-womb auditory experiences in the hospital can promote neural maturation in preemies at a critical developmental stage.
Travis and Scala explained that enhancing a preterm infant’s auditory environment—by simulating the in-utero speech-rich surroundings—provides a practical avenue to support brain development when the baby is outside the womb. The researchers also noted that the method is low-risk and easily scalable across NICUs, with the potential to improve long-term language outcomes for children born prematurely.
What this means for families and NICU care
Parents of preemies often grapple with stress, time constraints, and limited opportunities for direct, continuous contact. The study’s authors stress that while in-person visits remain vital for bonding and skin-to-skin care, sound-based interventions can be a meaningful supplement. “This is a way that—even if they can’t be there as much as they want—the baby is still hearing them and still knows that they’re there,” Scala said. The approach complements, rather than replaces, live interaction, and clinicians hope it reduces language-delay risks linked to premature birth.
The research was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, underscoring a commitment to translating early neuroscience into bedside practice. Follow-up studies are planned to explore whether benefits extend to infants with additional medical challenges and to better understand the mechanisms by which maternal speech shapes neural development in the NICU environment.
Looking ahead
As more NICUs consider incorporating structured maternal-voice exposure, this study lays the groundwork for standardized protocols that support language-network development in preemies. The ultimate goal is to give premature children a stronger start in language, communication, and overall cognitive trajectory—grounded in concrete neuroscience demonstrated at such an early age.
