Unborn babies remember music played to them in the womb long after birth, a study has found.

Many pregnant women play music for their babies in the belief that it might bring benefits. But until now, it has been unclear what impact sound has on a foetus.

The new study involved women in a learning group playing a CD of the nursery rhyme Twinkle Twinkle Little Star five times a week during the last three months of their pregnancy.

Soon after they had given birth, researchers measured the brain activity of their babies while playing the melody again.

A similar test was carried out four months later.

Both after birth and at four months, infants from the learning group showed much greater brain activity in response to the music than a control group of babies who had not heard it before.

The difference between the two groups was only apparent when the original music was played, rather than a version with changed notes.

Eino Partanen, from the University of Helsinki in Finland, said: “Even though we’ve previously shown that foetuses could learn minor details of speech, we did not know how long they could retain the information.

“These results show that babies are capable of learning at a very young age, and that the effects of the learning remain apparent in the brain for a long time.”

The research is published in the online journal Public Library of Science One.

In their paper the scientists speculate that unpleasant or noisy sounds heard in the womb might have adverse effects.

They wrote: “It seems plausible that the adverse pre-natal sound environment may also have long-lasting detrimental effects. Such environments may be, for example, noisy workplaces and, in the case of pre-term infants, neonatal intensive care units.”