Premature infants who are exposed to their parents voices in the NICU (neonatal intensive care unit) tend to have better vocalizations at 32 and 36 weeks gestational age, researchers from the Department of Pediatrics, Women and Infants Hospital, Providence, Rhode Island reported in the journal Pediatrics.

For a baby, vocalizing (uttering sounds) starts with the first cry. The mother, parents or caregivers start the communication process by responding to their baby's vocalizations. When the mother responds consistently to a baby's vocalizations (utterances), the baby starts acquiring language - learning which sounds are important for communications and survival. Experts say that continued successful communication development depends on two things: 1. The baby's ability to send messages clearly. 2. The parent's ability to interpret those messages.

Melinda Caskey, MD. and team set out to determine whether infants exposed to more adult language would make more vocalizations. They also studied the sound environment in the NICU of preterm infants.

Their prospective cohort study included 36 infants whose birth weight was 1250 grams or less. They carried out 16-hour recordings of the baby's sound environment in the NICU at 32 and 36 weeks' gestational age - a digital language processor was used. They gathered data on how many words were uttered by adults, total infant vocalizations, as well as conversational turns.

The authors inform that as early as 32 weeks, infant vocalizations were detected. Between 32 and 36 weeks there was a significant increase in infant vocalizations and adult word counts per hour. Even though infants were exposed to a relatively small percentage of time to language, this exposure increased considerably during those four weeks.

The researchers found that the number of conversational turns per hour were much higher when a parent was present, compared to no parent present at both 32 and 36 weeks.

The authors found that premature infants start making vocalizations at least 8 weeks earlier than the typical starting date for a newborn - over time, these utterances increase considerably.


Mom and Premature Baby at Kapiolani
Mother and preterm infant, Kapiolani Medical Center NICU, Honolulu


Even though infants are exposed to an ever-increasing amount of language as time passes, exposure to adult language makes up only a tiny proportion of all the sounds they hear in the NICU.

The investigators concluded in an Abstract in Pediatrics:

"Exposure to parental talk was a significantly stronger predictor of infant vocalizations at 32 weeks and conversational turns at 32 and 36 weeks than language from other adults. These findings highlight the powerful impact that parent talk has on the appearance and increment of vocalizations in preterm infants in the NICU."

Written by Christian Nordqvist