The Sound of Mother’s Voice in Womb

May Aid Fetal Brain Growth

Babies may get a brain boost in the womb when they    hear the voices and heartbeats of their mothers, a new study suggests.

Researchers studying fetal development and premature babies in the hospital found that the sound centers in the babies’ brains grew more quickly when they heard recordings of their mothers rather than the normal clamor of intensive care units. The recordings were manipulated to simulate sounds heard in a womb.  The study shows preemies who heard recordings from mom showed a larger auditory cortex

Babies begin to hear at 25 weeks’ gestation.  Previous research in fetal development has shown that fetuses respond to the sound of the mother’s voice. There’s very strong evidence that at birth, full-term babies show strong preference for the language they heard in utero and the voice of their mother over other women.

For this latest study, the researchers chose a group of premature babies who were born at 25 to 32 weeks. Nineteen were randomly assigned to hear the normal noises of the hospital, while 21 heard recordings of the voices and heartbeats of their mothers. The second group listened to the recordings for three hours a day.

After a month, the study authors used ultrasound scans to measure parts of the brains of the babies. Those infants who heard the recordings had larger sound centers — the auditory cortex — in their brains.

The findings do not prove that the brains of these babies are necessarily better, and researchers cannot conclude that they will end up with no developmental disabilities. They don’t know the advantages of having a bigger auditory cortex.

It’s also not clear if mothers’ voices are crucial inside the womb or if the voices of other people might also make a difference.

Still, the research suggests that parents of premature babies need to talk to them during visits in the hospital. “Hold your baby, talk to your baby, sing to your baby,” Researchers did caution that recordings should never be a substitute for actual visits from parents.

Mothers visiting their premature babies in the newborn nursery should be continued as this has so many other valuable effects as well.

A new study appears in the Feb. 23 issue of Proceedings of the American Academy of Sciences.