A fascinating video has shown unborn babies reacting to music in the womb as early as 16 weeks, as part of a study into foetuses and sounds.
In the video, the babies appear to be 'singing' as their mouths open and tongues begin to move when the music is played.
Scientists at Instituto Marques in Barcelona studied pregnant women between 14 and 39 weeks and played music via an intravaginal device (called a 'Babypod') and speakers on the bump.
They uploaded the results on their YouTube channel, in the "first study" of its kind.
Although it was previously known an unborn baby's ear is developed at 16 weeks, experts didn't think they were able to hear until 18 weeks.
Throughout the study, published in the journal Ultrasound, researchers used ultrasound to see how the babies reacted after hearing music.
When exposed to sound emitted via the intravaginal device, 87% of babies reacted with head and limb movements.
And 50% of them reacted with more striking movements, such as opening their jaw very wide and sticking their tongues out.
The study revealed babies were able to hear as early as 16 weeks.
Dr Marisa Lopez-Teijon, who led the study, said the findings show a foetus responds to music transmitted intravaginally by moving their mouth and tongue, "as if they were trying to speak or sing".
She also noted this method could potentially be used to rule out foetal deafness as well as stimulating communication skills before they are born.
The researchers added, according to the Daily Mail: "Foetal response begins at 16 weeks, with statistically significant variations throughout the pregnancy.
"The further on the mother is in the pregnancy, the more striking the facial movements. We are aware of and recognise the importance of talking to babies from the moment they are born to promote neurological stimulation.
"Now we have the amazing opportunity to do this much sooner, which is a huge advance."