Mary Kay Letourneau, 36, is serving a seven and a half year sentence at Washington Corrections Center, Purdy, after admitting sex with the teenager.

She gave birth to a girl, Georgia, on Friday night in a nearby hospital.

It is not clear what will happen to the baby as inmates cannot keep children in prison.

Mary Kay in jail before Georgia's birth

Letourneau has said the father is the 15-year-old former student, and says the baby was conceived in January after she was released from jail on condition she stop contact with the boy and undergo sex-offender treatment.

Letourneau was sent back to prison in February after she and the boy were found together in a car.

She first met the boy when he was a nine-year-old student in her classes at elementary school in Seattle. The relationship became sexual when he was 13.

Letourneau's husband has since divorced her and has custody of their four children.

The boy has repeatedly denied being a victim, and his mother has said she accepts Letourneau as one of the family.

She is already caring for their first child, who was born last year.

The boy is reported to have been in Europe promoting a book co-written with Letourneau about the affair. He was not present at Georgia's birth.

Meanwhile, a 38-year-old physical education teacher accused of having a sexual affair with a 15-year-old student in Florida has been charged with three counts of lewd, lascivious or indecent assault or act on a child.