06/01/2005 AT 12:10 AM EDT
Rod Stewart and Penny Lancaster confirmed on Wednesday that they are expecting a child.
"It will come as no surprise that Penny and I wanted to start a family as soon as possible," the Grammy winner and Rock Hall of Famer tells PEOPLE exclusively, adding that he is "overjoyed and extremely proud."
"The best news of all is Penny is feeling just wonderful, is very happy and looks more radiant than ever," Stewart adds.
The rocker, 60, and his 34-year-old model-photographer fiancée, say that they postponed confirming earlier reports of the pregnancy until Lancaster reached her 12th week, so that they could notify family members.
The couple, together for nearly six years, say the baby is due in December, and afterward they will aim for a spring 2006 wedding.
This will be Lancaster's first child, while Stewart has five children from previous relationships: Kimberly, 25, and Sean, 24, by first wife Alana Stewart; Ruby, 17, with former girlfriend Kelly Emberg; and Renee, 13, and Liam, 10, from his marriage to second wife Rachel Hunter.
For more on this story, pick up PEOPLE magazine on newsstands Friday.