Gertner and Marshek, who were married in November 2010, are expecting their first child via surrogate Feb. 1, 2015.
"We are beyond excited to become parents," Gertner told Playbill.com, "and we can't wait to meet the little guy."
Gertner made his Broadway debut in The 25th Annual Putnam County Spelling Bee. He was seen on Broadway, on tour and in the West End (receiving an Olivier nomination for Best Actor in a Musical) as Elder Cunningham in The Book of Mormon.