Nicole Kidman and Keith Urban use a secret code to tell their kids they want to have sex.

How to approach having sex with kids in the house can be an agonising decision for parents.

Do you lock the door? Sneak away and hope for the best? Wait until they’re definitely asleep?

It seems parents may have been over-thinking it if Nicole Kidman‘s recent revelation is anything to go by.

Kidman and husband Keith Urban simply tell their children they need alone time using a secret code-word for sex, the Australian actress shared with US TV hosts of The Moms.

“[We tell them] Mummy and Daddy need to have kissy-kissy time,” the 49-year-old told Denise Albert and Melissa Musen Gerstein when asked about intimate time while the kids are home.

It seems the couple’s daughters – Faith Margaret, 6, Sunday Rose, 8 – are happy to leave their parents to enjoy their alone time. Although the trick may not work so well if Kidman’s two adult children Isabella and Connor are in the house.

The pair’s sex life could be interrupted one day soon, however, with The Lion star also revealing that she hasn’t ruled out having more children, and neither have her daughters.

“One of them wants another [another sibling], the other one doesn’t,” Kidman said in the interview.

“I never say never because the maternal pull is strong.

“My sister has six children… My grandmother had her last child at 49. They said she’d been the oldest woman to give birth in the hospital. At that time that was pretty unusual.”

Listen: Sister Antonia Kidman speaks to Mia Freedman about raising six kids on No Filter.