Celebrity mum Nicole Richie has urged pregnant women to tell strangers to keep their hands off their bellies.

The former reality TV star-turned-designer admits that was the worst part of being pregnant with son Sparrow and daughter Harlow, who are now seven and eight, respectively, and she thinks all mums-to-be should stand up and demand to be left alone.

"I would say, 'Don't let anyone touch your stomach. Don't let everyone think they have the right to just touch you'," the 34-year-old star tells People magazine. "Who wants that? Nobody."

And she's also sharing another piece of new mum wisdom she picked up - don't listen to other parents.

"There's not one way to raise children," she adds. "There's not one way to be a mother. It really depends on your house and your lifestyle."

That said, there are a few things the mum-of-two, who is married to rocker Joel Madden, would have done differently: "I was very quiet around my kids when they were babies and now they're light sleepers," she explains. "I wish that I had been a little more rough with them."

But Nicole, whose dad is soul singer Lionel Richie, loves being a mum, revealing her kids make her laugh every day.

"I'm always finding (funny) pictures on my phone of them that they take, and videos that they take," the House of Harlow designer chuckles.

Nicole recently embraced Alicia Keys' no makeup campaign, revealing she has never been a fan of cosmetics.

"I know people (who) are so comfortable in makeup and they feel alive and that is what they love to do," she recently told PeopleStyle, "so I wouldn't say that I am against it because I know people that really get joy and feel the most like themselves when they put on makeup. I feel the most like myself when I don't have any on and so that's the road that I go down.

"Some people love to wear makeup and that's their thing. They like it. They're comfortable in it. It's not something that I would do. I like having a bare face. That's me."