The 44-year-old actor said the five-month-old boy, the fifth child of the couple, has become a "symbol" of a new phase in their marriage, reported People magazine.
"I feel like Beau is really the pillar of the rebirth of our relationship because our relationship had to crumble for it to be rebuilt and it was really important that we just start it over.
"I think Beau is a symbol of that because he's the first baby out of all five that we're raising in a communicative way," Spelling said at the seventh annual Santa's Secret Workshop event here.
Spelling and McDermott tied the knot in May 2006.