Posting a picture of his expectant wife caressing her baby bump, the Backstreet Boys band member joked, "The Easter Bunny brought a very special egg this year!" The couple, already parents to 5-year-old son Mason, met in 1993 and have been married since 2000.
This will be the sixth child born to a member of the pop quintet: Brian Littrell has one son, Baylee; AJ McLean has one daughter, Ava; and Howie Dorough has two sons, James and Holden. Nick Carter, who has no children, proposed to fitness expert and actress Lauren Kitt in the Florida Keys on Feb. 20.
Before he welcomes his second child, Richardson will join his bandmates to celebrate the group's 20th anniversary with a special concert in L.A. April 20.
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!