The former wrestler and her husband, Jared Pobre, are due to welcome a sibling for son Bodhi Brooks, 17 months, and five-year-old daughter Ava Grace, in May (20).
"Seeing the dynamic between our two kids is what made us want to have more kids," the 40-year-old mum-to-be tells People.com.
"We live in Jackson Hole, (Wyoming), and it's so nice to just have a little tribe there."
Tech entrepreneur Pobre adds, "It's exciting. I think once we had our second one, we totally got it and understood how to manage."
The couple wed in 2014, a year after Keibler split from Clooney.