Williams, who has a two-year-old daughter with Field, is over the moon with the news that the couple will have a baby boy, reported The Daily Star.
"Robbie is expecting a boy and is over the moon. They went for scans recently when they were in LA and once again got the doctor to put the sex of their baby in an envelope so they could take it away and open it later. They went out for dinner and opened it after dessert," a source said.
Williams first announced the happy news he and his wife were expecting their second child back in April. "Ayda and I are delighted to announce that Theodora Rose Williams is going to be a big sister," he had tweeted.