The 29-year-old actress is expecting her first baby with her fiancé Jason Sudeikis and she is trying to follow the example her mother, TV documentary maker Leslie Cockburn, who traveled to war zones while she was expecting Olivia and her two other children, Chloe and Charles.
When Olivia is worrying about things like whether she is exercising too much while expecting, she reminds herself of what her mother was capable of doing.
During an appearance on 'The Tonight Show with Jay Leno,' the 'Rush' star said: "I have a great mom. But she set the standard quite high. When I'm worrying about, 'Am I allowed to get on the treadmill?' My mom's like, 'I was in warzones with you guys!' It's good. It makes me feel like I'm not afraid of anything, I can keep going."
Olivia also revealed lots of people don't realize she is expecting or aren't sure because her bump isn't huge and so don't mention it for fear of insulting her.
She added: "I find that people will go to such great lengths to not mention it. People will be like, 'Hey would you like a glass of whiskey?' Or, 'You want to get on this roller coaster?' And I'm like, 'Oh well I'm actually pregnant.' And they go, 'What!?'
"I think it's because unless someone is watching you give birth they don't want to make the wrong call, because that's the worst thing in the world - when you congratulate a non-pregnant woman on her pregnancy."