Premature births are defined as any baby delivered before 37 weeks gestation. About 15 million premature infants are born around the world each year, and nearly 1 million of them can't be saved. Those that do survive are at an increased risk of developing hearing and language deficits due to underdevelopment of the brain. A new study published in the Proceedings of the National Academy of Sciences has indicated that premature infants benefit from hearing the sound of their mother’s voice, and it could even help the baby overcome some of these neurodevelopmental shortcomings.

“Brain development is largely shaped by early sensory experience,” the authors wrote in the paper. “However, it is currently unknown whether, how early, and to what extent the newborn’s brain is shaped by exposure to maternal sounds when the brain is most sensitive to early life programming.”

The study used 40 preterm infants who were born between 25 and 32 weeks of gestation, which is considered severely preterm. Ultrasounds of the infants’ brains were taken at birth, with a follow up when the baby was approximately one month old. The infants who had been exposed to sound recordings of their mother’s voice while in the incubator during this time were shown to have more well-developed auditory cortices than their peers who were not.

“Results show that newborns exposed to maternal sounds had a significantly larger auditory cortex (AC) bilaterally compared with control newborns receiving standard care,” the authors continued. “The magnitude of the right and left AC thickness was significantly correlated with gestational age but not with the duration of sound exposure.”

Prior research has shown that fetuses can respond to sounds in the womb at 25 weeks of gestation, and they can recognize the sound of their mother’s voice after birth as well. This study seems to bolster the importance of playing recordings of the maternal voice while in the incubator. However, that’s not to say that listening to the mother’s voice is the only voice that will produce this effect. The voice of the father or another individual the infant may have become familiar with in utero could possibly produce similar results. These factors will likely be tested in future research. Additionally, the researchers would like to determine if listening to recordings of the mother could also benefit infants who were not born premature.

“Our results demonstrate that despite the immaturity of the auditory pathways, the [auditory cortex] is more adaptive to maternal sounds than environmental noise. Further studies are needed to better understand the neural processes underlying this early brain plasticity and its functional implications for future hearing and language development,” the authors conclude.