Mother's Voice May Shield Sleeping Newborn From NICU Noise

By Marilynn Larkin

August 19, 2019

NEW YORK (Reuters Health) - Babies in the neonatal ICU who are exposed to their mothers' voice during sleep are less likely to awaken after loud bursts of ambient noise, especially if they were born at or after 35 weeks' gestation, researchers say.

"Sleep is increasingly recognized as a critical contributor to cognition and to general health and well-being," Dr. Renee Shellhaas of the University of Michigan in Ann Arbor told Reuters Health by email. "Newborn infants who are ill or who are born prematurely may require extended care in a neonatal intensive care unit (NICU) during a time of critical brain development."

"Our previous work demonstrated that quantitative neonatal sleep measures can be predictive of neurodevelopmental outcomes, and also that sleep is very frequently disturbed in the NICU setting," she said. "The current study (shows that) exposure to a mother's voice recording may insulate NICU patients from some of the impact of unavoidable facility noise by reducing the likelihood of wakefulness during the highest peak noise levels."

"NICU patients born at or after 35 weeks gestation, but not more premature neonates, showed sleep-wake patterns that appeared to respond increasingly with age to enriched exposure to their mother's voice," she noted. "This raises the possibility that newborns may become progressively more responsive to their mothers' voice as they approach full term."

Further, she added, "interventions designed to improve sleep in newborns who require intensive care may need to be tailored according to gestational age."

Dr. Shellhaas and colleagues studied 47 neonates who underwent 12-hour polysomnography. Their mothers were recorded reading children's books. Continuous maternal voice playback was randomized to either the first or second six hours of the polysomnogram.

As reported online August 13 in Pediatrics, after adjustment for peak noise, gestational age and neurologic examination score, the probability of the infant being asleep during any given polysomnogram epoch was higher with - versus without - maternal voice exposure.

However, the 20 neonates born at 35 weeks' gestation or later - in contrast to those born at 33 to 34 weeks - showed an age-related increase in the percent time awake; a decrease in overall sleep; a reduction in rapid eye movement sleep bouts per hour; and an increase in sleep-wake entropy solely during the six hours of maternal voice exposure.

These associations remained significant after adjustment for neurologic examination scores and ambient noise.

Summing up, the authors state, "Hospitalized newborns born at or >35 weeks' gestation but not at 33 to 34 weeks' gestation show increasing wakefulness in response to their mother's voice. However, exposure to the mother's voice during sleep may also help protect newborns from awakening after bursts of loud hospital noise."

Dr. Sourabh Verma, Associate Medical Director of the Neonatal Intensive Care Unit at Hassenfeld Children's Hospital at NYU Langone Health in New York City, told Reuters Health, "The findings are interesting and clinically relevant."

"We know that maternal voice exposure in preterm and term infants is associated with better cardiorespiratory stability," he said by email. "This new finding certainly adds to our understanding of complex neonatal sleep physiology. Also, this finding is in sync with growing evidence that maternal voice exposure may potentially benefit infants in their early days of life."

"Sleep is extremely important in both premature and term infants, although ideal duration and quality of sleep, as well as how sleep disruption exactly impacts long-term neurodevelopmental outcomes, remains unknown," he said. "There seems to be increasing evidence suggesting benefits of bedside parental talking, story reading and exposure to relaxing music even at early stages of neonatal life."

"Future studies are needed to better define the strategies that could be implemented in the NICU to ensure better quality sleep, aimed at improving long-term neurodevelopmental outcomes," he concluded.


Pediatrics 2019.