Jessica Simpson has an insatiable appetite for sex during pregnancy.

The singer admits she can't get enough lovemaking with fiancé Eric Johnson as the countdown to delivery begins.

The heavily-pregnant star, who was once called "sexual napalm" by ex-boyfriend John Mayer, says: "I'm kinda unstoppable at the moment."

And Jess admits sex has never been better.

She told Los Angeles DJ Ryan Seacrest: "The big O (orgasm) is, like, the biggest O ever."

But Jessica, who is due to give birth next month, reveals she "freaked out" after suffering a false labor recently.

She said: "I had contractions last night and I freaked out a little bit. You know those Braxton Hicks things.

"It's like these contractions that pregnant woman have towards the end. It prepares your body for delivery. I'm prepared. It's scary. It's like: 'Oh God, this can happen right now.'"

Go to The Sun for more.