The birth of the couple's first child comes after Mara revealed she was expecting in February. The actress showed off her bump in a short, long-sleeved white and silver dress as she stepped out for Elton’s John‘s annual AIDS Foundation Oscars Party.
“Went on a date with our bun in the oven,” Mara also wrote on Instagram.
Mara and Bell have been dating since 2015 and got engaged in 2017. The former Fantastic Four co-stars announced in July on social media that they had tied the knot.
Bell has previously opened up about the challenges of fatherhood, having been abandoned by his own father when he was young.
"It's difficult raising a child. It's really stressful. It requires a lot of you. You have to sacrifice your life and some people don’t want to do that. It's not particularly noble, but I could see why the easier thing is to leave," he said in an interview with ES Magazine. "You can't be thinking, 'I'm doing this because no one ever gave me this experience.' The thing is not to love from a place of anger, because that is potentially devastating."
Congrats to the couple!
WATCH: Kate Mara And Jamie Bell's Cutest Couple Moments.