January Jones' baby bump made its red carpet debut!

The 33-year-old actress, who hasn't revealed who the father of her unborn child is yet, showed off a growing belly at the premiere of "X-Men: First Class" on Wednesday night in NYC -- where she was wearing a black and blue Preen dress with Prada heels.

The rest of the cast was in attendance as well, with Kevin Bacon, James McAvoy, Michael Fassbender, Zoe Kravitz, Rose Byrne and Lucas Till all showing up in classic cars to the premiere.

Notably absent: Jennifer Lawrence, who is currently filming "The Hunger Games."

The movie opens June 3. January is due in the fall.

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