nicole kidman and keith urbanNicole Kidman and Keith Urban know the sex of their unborn baby - but they’re not telling.

Speaking before rehearsals for the Academy of Country Music Awards in Las Vegas yesterday, Keith told KCYE that they know “but I’m not saying”.

He added: “I’m glad we found out though, because it brought it home, you know what I’m saying.”

Nicole is currently seven months pregnant with their first child together, although she already has two children Isabella and Connor from her previous marriage to Tom Cruise. Earlier in the week, Nicole and Keith were spotted book shopping near their home in Nashville, Tennessee.

The Moulin Rouge star was spotted reading the ‘Week 30′ chapter of ‘Your Pregnancy Week By Week’ while Keith was spotted reading ‘Pocket Dad’, containing tips on how to do vital dad-to-be things like whistling, barbecuing and unblocking toilets.

An onlooker reported: “They looked so happy and so cute together. They were both pointing at the books and sharing a laugh about what they were doing. You can tell they are thrilled at being pregnant and loving every minute of it.”