DUBLIN, Calif. (AP) _ A pregnant Autumn Jackson, convicted of trying to extort $40 million from Bill Cosby by claiming to be his out-of-wedlock daughter, has begun her prison term of 26 months.

Ms. Jackson turned herself in Wednesday at the Federal Correctional Institution in Dublin. She will remain there for 30 days before moving to a prison maternity program in San Francisco, where she is due to deliver twin boys in late July.

After the births, she will complete her sentence at Dublin.

Ms. Jackson was sentenced in December after testimony showed she faxed Cosby a threat to tell her story to the tabloids. Cosby admitted that he had a sexual relationship with Ms. Jackson's mother but denied Ms. Jackson was his daughter.