The presidential couple's daughter, Jenna Bush Hager, 31, an NBC "Today" show correspondent, told the morning show Wednesday that she is pregnant with her first child, due in the new year.
Bush Hager and husband, Henry Hager, married in May 2008 at the Bush family ranch in Crawford, Texas.
Hager worked as a White House aide and on Bush's presidential campaign. His father, John Hager, previously served as Virginia's lieutenant governor.
In an interview conducted by phone, "Today" anchor Matt Lauer asked the former president what he would like his future first grandchild to call him. Jenna suggested "Popsicle,'' according to NBC.
"Sir,'' countered the former president.
Last month, Bush Hager announced her new role as editor-at-large of Southern Living magazine. She will continue working as a "Today" correspondent.
"I'm kind of a homesick Southern person, a Texan living here in New York," the expectant mom told Lauer last month. "I do miss the slow Texas way."
"I think it's fun to be able to talk about what the new generation of Southern women are doing, which is balancing a lot," she said.