"Mother and baby are doing great," the actress's husband, Eric Zee, tells PEOPLE.
Cooper Dominic Zee was born at 2:23 p.m. at St. John's Hospital in Santa Monica, Calif. He weighed in at 8 lbs. 9 oz. Cooper joins his 4-year-old sister, Michaela.
Ming-Na, 41, played Dr. Deb Chen on ER, and this year she was cast on the NBC drama, Inconceivable, which was set in a fertility clinic. (The show has been pulled from NBC's schedule.)