Nicole Richie has joked she "offered" her own children to Jessica Simpson to prepare her for motherhood.

The stars are working together on TV show Fashion Star and Nicole insists she didn't have too much parenting wisdom to share with the expectant songstress.

However, Nicole did have another idea for helping Jessica prepare for motherhood.

"I offered for her to take my kids up until she has hers," she told Access Hollywood. "That didn't really work, but the offer still stands because she hasn't had her kid yet.

"If she wants to take them, go ahead. I will go to Cabo, no problem."

Nicole has daughter Harlow, four, and two-year-old son Sparrow with Joel Madden.

Jessica is expecting her first child with fianc Eric Johnson.

Nicole also talked about her penchant for watching Bravo's reality TV show The Real Housewives of Beverly Hills. The star is a little obsessed with the popular series.

"I don't feel guilty about it at all, so I don't know if it's my guilty pleasure. I just love it. I'm a big Lisa VanderPump fan," she said before adding she isn't a fan of the other Real Housewives series.

"It's a big time commitment, so I only have enough room in my heart for one at a time."