This is the touching moment a baby appears to join her mother singing.

The footage, captured at a home near St. Louis, shows a two-month-old girl giggling and babbling as her mother -who is a songwriter- performs a song that she wrote for her.

The mother writes: ‘’I decided to write a song for her, called 'Smile'.

‘’I noticed that when I sang it to her, she lit up and was instantly enthralled so much to where she started singing along with me, which is incredible given that she was only two months old.’’

The story of the video - I (the mother) am a songwriter, and I had just had a little girl (in the video). I decided to write a song for her, called "Smile." I noticed that when I sang it to her, she lit up and was instantly enthralled so much to where she started singing along with me, which is incredible given that she was only two months old. So all of this sparked my interest to film it and share it.