Two sourced confirmed Mara's pregnancy to ET last month.
Kate Mara is showing off her growing stomach!
The couple's night out marks their first public appearance since two sources confirmed to ET last month that they're expecting their first child together. Bell, 32, already has a 5-year-old son, Jack, with his ex-wife, Evan Rachel Wood.
Mara was glowing at the event, sporting a short, long sleeve, white Giambattista Valli dress, which she paired with a Tyler Ellis clutch and black Jimmy Choo heels. Her handsome date opted for a classic Dior tux for the occasion.
While inside the event, the expectant parents posed with their host, Elton John, while the mom-to-be snagged a snap with Diane Lane as well.
Following their time on the carpet, Mara took to Instagram to officially confirm her pregnancy for the first time. "Went on a date with our bun in the oven," she captioned the pic.
Ritter, 37, was glowing as she posed alongside her longtime boyfriend, Adam Granduciel, while cradling her bump.
Ritter shared pics on social media as well, simply captioning the shots, "Surprise!!!"
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