Foetuses can distinguish between people speaking to them in English and Japanese a month before birth, researchers have found.
Foetuses can hear things in the womb, including speech although it was muffled, they could still perceive the rhythm of a language, and the study suggested that foetuses could differentiate between different types of language based on rhythmic patterns.
Researchers at the University of Kansas used a magnetocardiogram to measure the magnetic field produced by electrical activity in the heart. The study involved 24 eight-month pregnant women.
A bilingual speaker made two different recordings, on each in English and Japanese which was played back successively to the fetuses.
English and Japanese were chosen because they are said to be rhythmically distinctive, with English speech having a dynamic rhythmic structure resembling Morse code signals, while Japanese had a more regular-paced structure.
According to the researchers, the heart rates of the foetuses changed when they heard the unfamiliar language (Japanese) after having heard English speech.
Their heart rates did not change when they were read a second passage of English instead of Japanese.
According to the lead author, the study conducted by researchers at the University of Kansas Medical Center, had implications for fetal research in other fields.
"Research suggests that human language development may start really early - a few days after birth," says Dr Utako Minai, associate professor of linguistics and the team leader on the study, IANS reported citing agencies.
''Pre-natal sensitivity to the rhythmic properties of language may provide children with one of the very first building blocks in acquiring language,'' Minai adds.
''The intrauterine environment is a noisy place. The foetus is exposed to maternal gut sounds, her heartbeats and voice, as well as external sounds.
''Without exposure to sound, the auditory cortex wouldn't get enough stimulation to develop properly. This study gives evidence that some of that development is linked to language,'' explained Kathleen Gustafson, a research associate professor at the university.