Summary: Hearing their mother’s voice appears to support the development of language pathways in the brains of premature infants. In a randomized controlled trial led by Stanford Medicine researchers, preterm babies who regularly heard recordings of their mothers reading showed more mature language-related brain connections on MRI than infants who did not receive those recordings.
MRI scans revealed measurable improvement in the left arcuate fasciculus, a white-matter tract that plays a central role in language processing. The findings indicate that increased exposure to maternal speech — even via recorded readings — can meaningfully influence early brain development in infants born preterm.
Key Facts:
- Language pathway development: Preterm infants exposed to recordings of their mothers’ voices developed more advanced microstructure in a critical language tract.
- Short, practical intervention: A few weeks of nightly recordings were associated with detectable neurological differences before discharge from the hospital.
- Low-cost, scalable approach: Playing maternal speech recordings in neonatal units offers a simple way to support cognitive and language growth for hospitalized preemies.
Source: Stanford
Hearing their mother’s voice supports development of language pathways in premature infants, a new Stanford Medicine-led trial finds.
In a randomized study published in Frontiers in Human Neuroscience, hospitalized preterm infants were assigned either to a treatment group that heard recordings of their mothers reading aloud or to a control group that did not. After the intervention period, MRI scans taken near the time of hospital discharge showed that infants who heard their mothers’ voices had more mature structural connectivity in the left arcuate fasciculus compared with controls. This is the first randomized trial demonstrating a causal link between increased speech exposure and early brain development in preterm neonates.
“This is the first causal evidence that a speech experience is contributing to brain development at this very young age,” said lead author Katherine Travis, PhD, who conducted the study while at Stanford Medicine and is now at Weill Cornell Medical School and the Burke Neurological Institute. “It suggests a potentially transformative approach to neonatal care to promote better language outcomes for children born prematurely.”
The study’s senior author is Heidi Feldman, MD, PhD, Ballinger-Swindells Endowed Professor in Developmental and Behavioral Pediatrics.
Preterm infants—born at least three weeks early—often spend weeks or months in the hospital and, as a result, hear far less maternal speech than they would have experienced in utero. Parents are not always able to be at the hospital full time due to work, other children, or other obligations. Since premature infants are at elevated risk for later language delays, researchers hypothesized that reduced early exposure to speech could be one contributing factor.
To address this gap, the research team supplemented infants’ auditory environment by playing recordings of each baby’s mother reading aloud. Mothers recorded a chapter of Paddington Bear in their native language. Recordings were played during nighttime hours in repeated 10-minute segments, totaling about 160 minutes per night, for several weeks near the end of the infants’ hospital stays.
Nighttime playback also blinded parents to group assignment, reducing the chance that parental behavior would influence outcomes. Clinicians reported that the recordings did not disrupt the infants’ sleep, and the intervention mirrored the kinds of exposures a fetus would receive late in a full-term pregnancy when the uterine wall thins and more external sounds—including maternal speech—reach the developing brain.
Study population and measures
Forty-six very preterm infants (born more than eight weeks early, gestational ages 24–31 weeks) who were medically stable and had moved from the neonatal intensive care unit to an intermediate care nursery were enrolled. Infants with major congenital anomalies or major complications of prematurity were excluded.
As part of routine pre-discharge care, infants underwent high-angular-resolution diffusion MRI and T1 relaxometry scans that included assessment of the arcuate fasciculus in both hemispheres. The left arcuate is specialized for language processing; the team focused on diffusion measures such as mean diffusivity (MD) and fractional anisotropy (FA), plus R1 (1/T1), to index microstructural maturation.
Results: More mature left-language pathway
Compared with control infants, those who heard maternal voice recordings showed significantly lower MD and higher FA and R1 in the left arcuate fasciculus—indicating more advanced microstructural development. The right arcuate showed smaller or no consistent effects, consistent with known lateralization of language processing in the brain.
“I was surprised by how strong the effect was,” Travis said. “Detecting differences in brain development this early suggests that what happens in the hospital matters—speech exposure matters.”
Researchers plan follow-up studies to determine whether similar benefits occur in infants with more complex medical needs, to examine the mechanisms by which maternal speech supports neural maturation, and to explore how to optimize auditory environments in neonatal units. Melissa Scala, MD, co-author and neonatologist at Lucile Packard Children’s Hospital Stanford, is leading efforts to create tailored sound plans for NICU patients to promote healthy brain development.
Encouragement for parents
Parents of preterm infants often experience stress and feelings of helplessness when they cannot be present as much as they wish. Clinicians emphasize that in-person visits and skin-to-skin contact remain valuable for neurodevelopmental outcomes. At the same time, voice recordings can supplement visits—allowing infants to hear their mother’s voice even when parents can’t be at the bedside and giving parents a tangible way to contribute to their child’s early brain development.
Funding: This research was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (grants 5R00-HD84749 and 2R01-HD069150).
Key Questions Answered:
A: Premature babies often miss the late-gestation sounds they would otherwise hear in the womb. Exposure to a mother’s voice may help close that auditory and developmental gap and support language-related brain maturation.
A: Mothers recorded a chapter of a children’s book in their native language. These recordings were played in repeated 10-minute segments during nighttime hours, totaling roughly 160 minutes per night for several weeks.
A: Infants exposed to maternal voice recordings demonstrated more mature microstructure in the left arcuate fasciculus—measured as lower mean diffusivity and higher fractional anisotropy and R1—compared with controls.
About this language development research news
Author: Erin Digitale
Source: Stanford
Contact: Erin Digitale – Stanford
Image: The image is credited to Neuroscience News
Original Research: Open access. “Listening to Mom in the Neonatal Intensive Care Unit: A randomized trial of increased maternal speech exposure on white matter connectivity in infants born preterm” by Katherine Travis et al., Frontiers in Human Neuroscience.
Abstract
Listening to Mom in the Neonatal Intensive Care Unit: A randomized trial of increased maternal speech exposure on white matter connectivity in infants born preterm
Objective:
Early speech exposure is believed to shape the brain structures that process speech, but prior work has been largely correlational. This randomized trial tested whether increasing maternal speech exposure for preterm neonates during NICU hospitalization causally affects structural maturation of white-matter tracts involved in language.
Study design:
Forty-six neonates born at 24–31 weeks gestational age were randomly assigned to increased maternal speech exposure (T, n = 21) or routine care (C, n = 25). The T-group heard 10-minute recordings of their mothers reading a children’s story twice per hour between 10 p.m. and 6 a.m., adding about 2.67 hours of maternal speech per day. The C-group received no recorded speech exposure. Near-term-equivalent MRI assessments included diffusion scans and T1 relaxometry. Primary outcomes focused on mean diffusivity (MD) in the left and right arcuate fasciculus; secondary outcomes included fractional anisotropy (FA) and R1 (1/T1).
Results:
Groups were similar on medical and demographic variables. Compared with controls, the treatment group showed significantly lower MD and higher FA and R1 in the left arcuate fasciculus across scans, indicating more mature microstructure. Effects in the right arcuate were smaller and not consistently significant.
Conclusion:
Increased exposure to maternal speech was associated with more mature left arcuate microstructure in preterm neonates, supporting a causal role for speech exposure in early brain development. Enhancing speech exposure in the NICU may help improve language outcomes for children born prematurely.