A source told the mag that the former "Felicity" star gave birth sometime in the last week. The outlet also reports that the 40-year-old's mother and brother, "have been staying with Keri for the last week, spending all their time doting over the baby."
The source added, "Keri and Matt both look overjoyed and are over the moon to be new parents. They are always snapping pictures of the baby, and family and friends have been sending gifts."
The actors just wrapped their fourth season of their hit FX show about two KGB spies who are in an arranged marriage.
Us Weekly first reported that that Keri Russell was expecting a child with her co-star back in January. Following months of speculation that they were in a relationship, the pair first stepped out publicly as a couple at NYC's The Public Theater in April 2014. Two years later the duo is taking their relationship to a whole new level.
A source at the time told Us, "Matthew is really in love. They feel they should have always been together."
Keri has two children from her previous marriage, son River, 8, and daughter Willa, 4. The actress was married to Shane Deary for seven years, but split with him in December 2013. Rumors soon swirled that the actress had taken up with her Welsh co-star shortly after her break up. Looks like the rumors were true!