The 'Black Panther' star also talked to ET about the impact of seeing kids dressing up as the black Marvel superhero.
*Story contains spoilers from the most recent episode of This Is Us.
The 41-year-old actor and his wife, Ryan Michelle Bathe, talked to ET's Ashley Crossan at the inaugural IndieWire Honors, which celebrated independent film and television, on Thursday night, where he revealed that Beth's unexpected homebirth on the show was inspired by what really happened to him and his wife.
"Six plus years ago, we had our first child, Andrew Jason Sterling Brown -- love you buddy -- at home in our bedroom. Not intentionally!" Brown explained.
"We were going to go to this birthing center -- it was this beautiful birthing center that we were going to go to, very civilized -- and that went out the window at, like, 11 o'clock in the evening," Bathe added.
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"My wife had her first contraction at 11 p.m., and Andrew came into the world at 2:23 a.m., 3 hours and 23 minutes later. It never happens like that the first time. It's not supposed to," Brown continued. "But my wife is not your ordinary human being, so she does extraordinary things all the time!"
Brown explained that the This Is Us show creator, Dan Fogelman, had seen him talk about the home birth on a show and decided that the storyline needed to become a part of the NBC drama.
"He's like, 'Oh, we gotta put it in the show, we gotta put it in the show,' and so they incorporated it into our [TV] life nine years ago," he said.
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It really is all in the family with the This Is Us cast, as was evident when Brown and his co-stars turned out for the real-life wedding of his TV brother, Justin Hartley, to soap star Chrishell Stause.
"It was magical. It was small. It was intimate. It was beautiful," Brown said of Hartley and Stause's nuptials. "It was everything I think that he and his lovely lady wanted, and we were just happy to be there."
"It was festive -- like people danced real hard afterwards. We had a few drinks. There was imbibement for all and just joy," he added.
Meanwhile, Brown, who stars in the upcoming Black Panther movie, explained that he felt a slightly different sense of joy when he witnessed the impact of seeing a black superhero inspire kids -- and their costumes -- over the Halloween weekend.
"To see those kids dressed up, black and white alike -- it's cool that a black superhero has crossover and universal appeal, so I'm excited to see how people respond to the film," he told ET.
We'll get to see that response when Black Panther hits theaters on Feb. 16. In the meantime, you can catch Brown on This Is Us, Tuesdays at 9 p.m. on NBC.
Watch the video below for more from the This Is Us cast on how their roles affect their real lives.