The True Blood actor, who wed his co-star at a private residence in California in 2010, opened up about his wife's pregnancy to Zap2it.
Moyer has two children from a previous relationship, while this is Paquin's first child.
"It's always amazing," Moyer said. "I love my kids so much, and I think that the fact that Anna is pregnant just adds more crazy to the bundle of fun."
In the same interview, Moyer hinted that Eric (Alexander Skarsgård) and his character Bill will form an alliance on the upcoming season of the HBO series.
The series returns for a fifth season on HBO on June 10 and on FX in the UK later this year.
Watch a promo for the fifth season of True Blood below: