Russell, 35, is already mom to son River, 4 1/2.
The actress initially announced her pregnancy in July, though she kept a low profile as her baby bump grew over the past few months.
Russell and Deary wed in 2007.
“I like getting to be in the adult world a little bit and then getting to be in the mom world and cook dinners,” she told People magazine in 2010 of juggling work life with family life. “And, for me, that balance is what makes it nice.”