Born in Atlanta, Ga. at 10:30 a.m., Quincy weighed in at 8 lbs., 8 oz., measured 20 inches long and joins big brother Sebastian Alexander, 6½.
"We are so blessed and grateful to God for this newest gift to our family," the couple, who married in 2007, tell PEOPLE.
Fields, 44, announced the pregnancy in July.
"It was planned. We've actually been trying for a couple years," she said at the time. "We had gotten pregnant twice and [miscarried]. If I'm encouraging to anybody ... it's not like I'm the poster child for over 40 and pregnant."