The 30-year-old actor accidentally revealed the sex of their second child in September on Jimmy Kimmel Live!, saying, "You can find out now at nine weeks, which is really bizarre. They do a blood test. They test if there are hormones in there. They go, 'Oh, you've got testosterone -- so you've either got balls or you're having a baby boy." Oops!
Back in November, the Birth of a Nation star opened up about his nerves over their new addition to ET at the Nocturnal Animals premiere.
"I'm a little nervous," he confessed. "You have a little more faith in the human mechanism. The only reason you're here and I'm here is because it works. We got through with one good baby, I think we can do it again."
For more on Hammer and Chambers, watch the video below.