October 7, 2025
3 min reading
Babies’ brains recognize foreign languages they heard before birth
Babies process foreign languages they heard in utero the same as their native language, researchers find
Babies begin processing language before they are born, a new study suggests. A Montreal research team found that newborns who heard short stories in foreign languages while in the womb processed those languages the same as their native language.
The study, published in August in Nature Communications Biologyis the first to use brain imaging to show what neuroscientists and psychologists have long suspected. Previous research has shown that fetuses and newborns can recognize familiar voices and rhythms and even prefer their native language soon after birth. But these findings come primarily from behavioral cues – sucking habits, head turns or changes in heart rate – rather than direct evidence from the brain.
“We cannot say that babies “learn” a language before birth,” explains Anne Gallagher, neuropsychologist at the University of Montreal and lead author of the study. What we can say, she adds, is that newborns develop familiarity with one or more languages during gestation, which shapes their brain networks at birth.
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The research team recruited 60 people for the experiment, all of whom were around 35 weeks pregnant. Of these, 39 exposed their fetuses to 10 minutes of pre-recorded stories in French (their native language) and an additional 10 minutes of the same stories in Hebrew or German at least once every two days until birth. These languages were chosen because their acoustic and phonological properties are very distinct from French and from each other, explains co-lead author Andréanne René, Ph.D. candidate in clinical neuropsychology at the University of Montreal. The other 21 participants were part of the control group; their fetuses were exposed to French in their natural environment, without any particular input.
Between the first 10 hours and three days after birth, the team observed how the newborns’ brains responded to German, Hebrew and French using functional near-infrared spectroscopy (fNIRS), a non-invasive imaging technique that measures changes in blood oxygenation in the brain.
All babies in the cohort showed increased activity in the left temporal lobe, the language processing center of the brain, when they heard French spoken. But only those exposed to Hebrew or German before birth showed similar brain activation when listening to those languages. Newborns who had not heard the Hebrew or German stories before birth showed activation in brain regions for processing sounds in general and less activation in regions for processing language.
The study supports the idea that the newborn brain is not a “blank slate,” says Ana Carolina Coan, an expert in pediatric neurology and member of the Brazilian Academy of Neurology. Instead, the gestational environment begins to shape fetal brain function even before birth.
It’s unclear how much in utero exposure to a given language is necessary for newborns’ brains to process it as language. Some previous research on the effects of the auditory environment on fetuses used exposure lasting several hours; other studies have used a duration of as little as 15 minutes. Gallagher was concerned that the exposure time in the new study wasn’t enough to note a response, but asking for more than that might have been burdensome for participants. So the clear results of the study were a pleasant surprise, she says.
“The study does not suggest that mothers should expose their unborn babies to foreign languages to become more intelligent or multilingual later,” says Coan, who was not involved in the research. But studying how in utero language exposure affects a child’s speech development will be important for understanding speech disorders, which affect about 5 to 10 percent of children in the United States. “For clinicians, this adds evidence that language development begins much earlier than birth, which is important for how we detect and treat delays,” she says.
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