The girl, who cannot be identified by law, gave birth on March 29 by Caesarean section in Colombia. She is one of the youngest mothers on record.
Under Colombian law, the 15 year-old father could be jailed for at least nine years for having sex with a child under 14.
But the authorities have been frustrated in their attempts to file criminal charges against him because the girl is from the ethnic Wayuu tribe which has its own laws.
Experts say that under Colombia's 1991 constitution the Wayuu have jurisdiction.
The baby weighed 5.6lbs and measured 14.5ins, but according to the doctor who delivered the child, the mother "barely understood what was happening" at the moment of birth.
Dr Fabio Gonzalez said he had to operate because at that age the pelvis is still growing "and it's too small for the foetus to pass through the vaginal canal".
He said the mother, who was discharged from the clinic in good health, is also relatively short at 4ft, 7ins.
When nurses took the newborn to her mother "it was as if a doll was being given to her", said Dr Gonzalez.
"She has no idea. She doesn't understand anything and that's normal," he added.
The doctor said it was not the first time he had delivered the baby of a 10-year-old girl. He said he had a similar case last year.
A Wayuu tribal leader, Rosa Iguaran, said they don't consider that the girl was raped but rather that the baby was conceived in consensual sex.
It will be up to the parents of both the boy and girl to decide whether the two should be married and what the boy's family owes the girl's family, whether it be "necklaces, cows, goats, whatever the family agrees on".