People.com reported Exton Elias Downey was 7 pounds, 5 ounces, and 20 inches long when he was born at 7:24 a.m.
"Everyone is healthy and they couldn't be happier," a friend of the couple told People.com.
The child is the first for the Downeys, who married in 2005. Downey Jr. also has an 18-year-old son from a previous marriage.
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