>> reporter: a baby arrives and a song is sung. ♪ >> reporter: another baby and again singing. ♪ i watch them grow >> reporter: and again and again. ♪ >> reporter: by this time something like 6,000 deliveries, 6,000 vocal performances brought off by a man whose name sounds like a 1960's pop lyric, carey andrew-jaja, obstetrician. >> to the family this is special. >> reporter: he works at women's hospital at upmc and has been singing to newborns since his training days because one of his teachers was also a singing obstetrician. >> he asked me to continue the tradition and i have done it ever since. ♪ happy birthday >> reporter: so much so that new mothers would be disappointed if dr. jaja had not sung when her daughter was born. >> first happy birthday. >> reporter: look at these faces. sure some science that says