Brady announced the birth Wednesday. He said the boy was born Tuesday and that he and Bundchen hadn't chosen a name. He called it "a wonderful experience in my life."
"Everyone's great," Brady said. "I didn't get much sleep."
Brady also has a 2-year-old son, Jack, with actress Bridget Moynahan. Bundchen is a mother for the first time. The birth was first reported by People.com.
Brady and Bundchen were married in February in Los Angeles in a small ceremony. In April, they held another wedding ceremony in Costa Rica for friends and family.
On Wednesday, Brady showed up 16 minutes late for his weekly media availability. Asked what was new, he said, "a normal week," and smiled.
"I owe it to the guys in the locker room to really focus on what I need to do for this team," he said, "and put all these emotions aside and kind of come in here with a great sense of determination on what we have to do as a team. So, as a captain and a leader of this team, the last thing they need from me is to be really not focused on the job at hand. There's plenty of things for me to really be doing here this week."
Moynahan released a statement Wednesday.
"I wish them the best with their baby, and I'm sure my son will enjoy having a half sibling," Moynahan said. "I ask the press to respect our privacy while we are welcoming this new addition to our extended family."
Copyright 2009 by The Associated Press