Russell, 34, and Hagner, 33, first began dating in 2016, following his split from ex-wife Sanne Hamers. They met while co-starring in the indie comedy Folk Hero & Funny Guy. The pair went on to tie the knot in September 2019.
ET spoke with Hagner in June, while she was promoting her recent comedy Palm Springs, and she addressed her and Russell's plans for expanding their family after having exchanged vows.
"I mean I'm not quite there," Hagner said at the time.
Reflecting on the expected increase in pregnancies due to coronavirus quarantines keeping couples locked in close quarters, Hagner joked, "I feel like there is going to be a major boom!"