But that doesn't mean an ol' pal like Laura Prepon can't gush over the future mom and dad.
"They're going to be wonderful" parents, their That '70s Show co-star told me at the 2014 Critics' Choice TV Awards before quickly adding, "I don't comment on my friends' private lives, but they're wonderful."
E! News was the first to report in March that Kunis, 30, was pregnant with the couple's first child just weeks after we exclusively revealed that Kutcher, 36, popped the questions with a massive engagement rock.
"The best day of my life so far was the proposal," Kunis says in the latest issue of Marie Claire. "I cried. I was a mess.
"Not to discredit any relationships in my past," the Friends With Benefits star said, "but this relationship is different."
She also tells the magazine about her plans for the birth.
"Two people are allowed in my delivery room: my doctor and my significant other," she reveals. "And [my future husband] is staying above the action. He'll be head to head. Not head to vag. Unless he wants to risk his life and see. But I wouldn't if I were him." Kunis graphically adds, "I highly doubt he wants to see that being ripped apart and shredded. Because it will be shredded. It's just a matter of how badly."
Until that day comes, Kunis is enjoying the perks of being pregnant—like having bigger boobs. "They're amazing! They've tripled in size. I was a 34A; now I'm a 36C. I'm so excited! I'm telling everyone I know, 'Go ahead, touch them!'" she says. "Without being an a--hole, I have to say, I love being pregnant."
Speaking of boobs, did you see how hot Prepon looked at Critics' Choice? Check out the video below.