Babysitter 'wholly unfit' to look after four-year-old he assaulted.
Stephen Biggs, 26, was looking after the children of a friend when the little boy had a tantrum and would not calm down, a court heard.
The boy, his three-year-old sister and their two-year-old brother were described as "boisterous" and the court heard the older two would frequently fight over toys.
The oldest child began to "throw himself about" as he had a tantrum saying he wanted his mother, Cardiff Crown Court heard.
Biggs, who pleaded guilty to one count of assault causing actual bodily harm, hauled the boy to his feet by the hood of his sweatshirt, causing him to lose his balance and fall down the stairs, Clare Wilks, prosecuting, said.
Ms Wilks said the doctor found that the injuries "appeared to be inconsistent with rough and tumble play".
Sentencing Biggs to eight months in prison, suspended for two years, Judge William Gaskell said: "You were quite clearly wholly unfit to look after this child."