Orlando, Florida // Foetuses show evidence of learning by their 34th week, three weeks earlier than thought, new research has found.
By that time they show signs of recognising nursery rhymes sung by their mothers, so much so that their hearts slow down.
“It really pushed the envelope” in terms of how early babies begin to learn, lead researcher Charlene Krueger, associate professor at the University of Florida’s College of Nursing, said on Thursday.
The study was published in the journal Infant Behaviour and Development.
It followed 32 women from their 28th to their 38th weeks of pregnancy in an investigation to pinpoint when the ability to learn emerges.
Ms Krueger had the women repeat three times out loud a 15-second nursery rhyme, and do it twice a day for six weeks.
The rhyme chosen was previously unknown to the mothers.
The foetuses’ heart rates were monitored at 32, 33 and 34 weeks as they listened to a recording of a female stranger recite the rhyme.
By the 34th week, Ms Krueger said, the heart rates of the foetuses showed an overall slight decline while listening to the recording, compared with a control group of foetuses whose heart rates slightly accelerated while listening to a recording of a new nursery rhyme.
A decelerating heartbeat has long been associated with the foetus recognising something familiar, compared with an accelerated heartbeat response to a novel sound or experience.
“We cautiously concluded, because it was not statistically significant, that learning emerged by 34 weeks gestational age,” Ms Krueger said.
At that point, the mothers stopped reciting the rhyme to their babies, who were tested again at 36 and 38 weeks.
“At 38 weeks we confidently concluded the foetus could remember the rhythm of that nursery rhyme, which was four weeks after the mother stopped reciting the rhyme,” Ms Krueger said.
“The deeper and more prolonged response [at 38 weeks], the more confident I felt that learning had gone on.”
The findings have implications for the care of pre-term babies in neonatal units.
Ms Krueger next wants to try placing recordings of the mothers’ voices in the babies’ cribs so they will benefit from positive effects of their mothers’ voices.
“What it really shows is how sophisticated the interaction is between a mother and her infant,” the lead researcher said.
* Reuters