The song's lyrics suggest Beyonce - who gave birth to Blue Ivy by caesarean section with Jay-Z by her side on Saturday - lost a baby before falling pregnant with their daughter.
The song, called Glory, has the words: "Last time the miscarriage was so tragic, we was afraid you disappeared". Jay-Z also sings about 'false alarms and false starts' but says Blue is his 'greatest creation', rapping:
"The most beautifullest thing in this world is daddy's little girl."
The sound of a newborn babies cries can be heard on the track, which also includes the lyrics:
"So there you have it, s--- happens."
"All the pain of the last time, I prayed so hard it was the last time. Your mama said that you danced for her, did you wiggle your hands for her?"
Congratulations to the couple, especially after the heart ache they must have been through.