Newborn preemies more vocal when parents are near

Even tiny preemies hospitalized after birth can make baby sounds - especially when their parents are talking to them, a small study suggests.

Very premature babies are known to be slower-than-average in picking up language skills. That can be due to various reasons, including health problems they may have as newborns.

It's not known whether the sounds preemies hear soon after birth, and their own ability to vocalize, are related to their later language development. But premature infants who spend their early days in the neonatal intensive care unit (NICU) are in a much different sound environment than they would be if still in the womb, said Dr. Melinda Caskey, a pediatrician at Women and Infants Hospital in Providence, Rhode Island, and the lead researcher on the new study.

In the womb, mom's voice is the most prominent sound, Caskey said. In the NICU, the beeps and whirs of medical equipment abound.

Until now, though, no studies had looked at how much language NICU preemies hear during their day.

Caskey's team found that in their hospital NICU, it was surprisingly little - with monitor sounds, general noise and silence being much more common.

"It's very striking," Caskey told Reuters Health, "especially when you compare that with what the fetus hears."

What's more, the study found, when preemies were hearing adults talk - their parents, in particular - they were more vocal themselves. That usually meant making short vowel sounds.

The significance of those vocalizations is not clear, according to Caskey. She and her colleagues are continuing to follow the infants to see whether their NICU language exposure and vocalizations are related to their language development later on.

If they are, Caskey said, "we would need to do a language intervention."

"We'd want both parents and nurses to talk to the infants more in their daily interactions," she said.

The findings, reported in the journal Pediatrics, are based on 36 very preterm infants - born, on average, during the 27th week of pregnancy. (Pregnancy normally lasts about 40 weeks.)

The researchers outfitted each baby with a vest that carried a digital recording device. The recorder captured environmental sounds and the infants' own vocalizations over two 16-hour periods - at what would have been the 32nd and 36th weeks of pregnancy.

Caskey's team found that the infants were already able to make vocalizations at week 32 - or eight weeks before what had been their due date.

And they were more likely to make those vocalizations when their parents were visiting, with baby sounds going up by as much as 129 percent.

Preterm infants begin to make vocalizations at least 8 weeks before their projected due date and significantly increase their number of vocalizations over time. Although infant exposure to language increased over time, adult language accounted for only a small percentage of the sounds to which an infant is exposed in the NICU. 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.