Krasinski, best known for his role as Jim Halpert on "The Office," married the 30-year-old "Devil Wears Prada" actress in Italy in 2010.
Blunt told Manhattan magazine last year that she and Krasinski hoped to have children, but needed to consider timing.
"We want to have children; I just don’t know when yet. I’m just not sure about the timing of all of that,” the actress said. “We’re both from big families so I think it’s something we want.”
"They both want kids, it's one of the reasons they got a bigger place, in a neighborhood that you can raise a family," a source told US Weekly. "They both couldn't be more excited."
Parenthood isn't Blunt's only upcoming role. She'll star with Johnny Depp, Chris Pine, Anna Kendrick in an upcoming adaptation of "Into the Woods."