Mila Kunis "forgets" how pregnant she is.

Mila Kunis

Mila Kunis

The 'Bad Moms' actress is expecting her second child with husband Ashton Kutcher and admits the experience is "very different" to when she was carrying daughter Wyatt, who was born in October 2014.

She said: "I forgot how far along I was today. I think with the first one, you're so enamoured with the initial experience that I was constantly checking the app, 'What fruit size is the baby? Is it the size of a grape or an avocado?'

"Now I'm like, 'Wait, how far along am I?'

"You're busy running after the other one and working full time."

The 32-year-old actress also recalled one of her favourite parenting moments, admitting she was left "dying laughing" when she caught her spouse desperately trying to clear up their little girl with an "entire roll" of paper towels following an explosive poop incident.

She recalled to 'Entertainment Tonight': "Sometimes babies projectile poop, and it was one of those days where there was a lot of poop.

"I turn around and he's like, 'I got it babe!' and I was like, 'Great!' And then I turned back around, and he literally bathed her in the sink, which is fine, and then wrapped her in an entire roll of paper [towels].

"I was like, 'What are you doing?' and he's like, 'Drying her up!' and he goes, 'I couldn't find the towel.' And I literally was like, 'What is happening!?'

"She was cocooned in this little Bounty roll, and I was like, 'Oh my god I love you so much!' It made me so happy. I took so many photos of it. I literally was dying laughing."

Mila previously admitted she relates to all the misfit parents depicted in her new comedy 'Bad Moms'.

She said: "I'm very young as a mother. I only have just 16 or 17 months, so I'm very new at this, but I would say 100 percent I have all the characters within me. Every mother does, and if they say they don't, then they are that person."