Looks like the stars of The Americans have a new mission — parenthood!

A source alleges Keri Russell is pregnant, and expecting her first baby with costar-turned-beau Matthew Rhys.

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keri russell and matthew rhys (photo credit: getty images)

“Keri is more than four months along,” an insider tells Us Weekly of the 39-year-old actress who already has two kids — River, 8, and Willa, 4 — with ex-husband Shane Deary. “It’s so exciting for them!”

The reported pregnancy marks baby No. 1 for the actor, 42.

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The costars and parents-to-be began dating in 2013 shortly after her marriage came to an end.

Congrats to the growing family!