Olwyn Hirst, 66, said she went on foreign holidays with the priest - known only as Father X - and he even took her to the Vatican to see the Pope.
Hirst denied five charges of blackmail. She was convicted of four charges involving pounds 10,000, pounds 15,000, pounds 20,000 and pounds 20,000, but cleared of one of pounds 6,000.
The jury heard that the child was allegedly born in Dorset in 1977, given to an American friend and the birth was never registered.
Hirst, of Bradford, West Yorkshire, had been convicted in 1979 of theft and forgery. She was remanded in custody for sentencing.Reuse content