A South African woman has pleaded not guilty to charges that she kidnapped a baby from a hospital nearly 19 years ago and raised the child as her own.

The woman faces charges of kidnapping, fraud and breaking South Africa's child protection laws, the African News Agency reported.

The woman told the court she had adopted the baby after struggling with infertility.

She said she was not aware the child was kidnapped, and the woman who facilitated the adoption told her a young woman had given the child up.

State prosecutors say the woman, now 50, allegedly snatched a three-day-old baby from her sleeping mother's hospital bedside in 1997. The prosecution also says the woman allegedly defrauded authorities when she registered the child as her own daughter in 2003, changing her birth date, the agency reported.

Celeste Nurse, the girl's biological mother, broke down in court as she recalled the day her daughter went missing, the agency reported.

Semi-conscious after a morphine drip, she thought a nurse picked up her crying baby. When she woke up her baby was gone.

"I was crying my heart out in the foetal position," said Morne Nurse, the girl's biological father, recalling the same day.

The Nurse family found their kidnapped daughter last year after their second daughter befriended a girl at school who looked remarkably like her.

After a police investigation and DNA tests, that new friend turned out to be their missing child. The alleged kidnapper was arrested and released on bail last March.

The girl, now 18 and known publicly by her birth name Zephany, uses the name given to her by her alleged kidnapper. A judge ordered that neither the woman nor the girl may be identified.