The father of a baby in an Auckland hospital's intensive care unit waited for the nurse to leave the room before helping to snatch the boy and go on the run.
The man, who cannot be named, pleaded guilty in the Auckland District Court to abducting a child on 21 March last year.
The man was sentenced to one year in prison in August last year, but court documents were only released to Radio New Zealand on Friday.
They say the man and his partner lost custody as soon as their son was born. He was in the care of Child, Youth and Family suffering from breathing and feeding problems.
His mother, who is still before the courts, was living at the hospital to help feed him.
The documents say she unhooked her son from machines he was connected to and left with her partner. They were caught the next day.
Judge Geoff Rea said it was an unusual case. He took into account the man's previous criminal history, which runs to four pages, and the fact he was serving a sentence of intensive supervision at the time.
Judge Rea said the baby was vulnerable, but there was no evidence that he suffered any long-term effects.