This is the third child for David, who has a 12-year-old daughter with ex-wife Courteney Cox.
David and Christina Arquette are now the proud parents of two boys.
The couple welcomed their second child on Wednesday and named him Augustus Alexis Arquette, with the middle name being a tribute to David's late sister, Alexis, who died unexpectedly in September. David, 45, and Christina, 35, happily shared the first photos of their bundle of joy on Instagram.
Augustus, who will go by Gus, will have some siblings to show him the ropes. The couple is already parents to 2-year-old son Charlie, and David also has a 12-year-old daughter, Coco, from his previous marriage to Courteney Cox.
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The Arquette family has excitedly been anticipating the birth of Gus. David spilled the news that he and Christina were expecting in October by posting a video to Instagram of Charlie kissing Christina's sonogram while saying, "Hi, baby."
"So incredibly blessed and honored that my wife @christinaarquette is pregnant with a baby boy!" David captioned the sweet post. "Thank you Christina and humbled gratitude to G-D for this tremendous gift! Charlie and Coco are so excited and I am over the moon!!!"