PARENTHOOD is bound to be a hot topic tonight as Madonna visits David Letterman’s “Late Show” for the first time in three years.

Mommy Madonna, 45, is the mother of a seven-year-old girl, Lourdes Maria Ciccone Leon (dad is Carlos Leon), and a three-year-old boy, Rocco Ritchie (with hubby Guy Ritchie).

Daddy Dave, 56, is the brand-new father of a baby boy, Harry Joseph Letterman, born Nov. 3. His mom is Letterman’s long-time and seldom-seen girlfriend, Regina Lasko.

Madonna’s also an author of kids’ books these days, although no one’s likely to confuse her with Dr. Spock. Her appearances on “Late Show” have been infamous ever since 1994, when she shocked viewers – and Letterman – by uttering the F-word 13 times (the word was bleeped).

This time around, the only dirty talk you’re likely to hear will be about dirty diapers.

TALE OF THE TAPE

Family Affair

Dave vs. Madonna: Who’s the better parent?

Challengers Madonna, 45, mother of two

David Letterman, 56, new father of one

As a role model

Madonna

Hard work and showbiz savvy made her a zillionaire. But the kids will want to know: What was the deal with that cone-shaped bra?

Dave

Except for speeding tickets, his record’s clean. Advantage: Dave

Silver spoons

Madonna

She’s as rich as Oprah. Advantage: Madonna

Dave

He’s as rich as Dr. Phil.

Where they’ll grow up

Madonna

Rainy England’s a downer.

Dave

Take your pick: Westchester, Tribeca or Montana – Harry Joseph’s a home boy. Advantage; Dave

Roots

Madonna

Bay City, Mich.

Dave

Indianapolis.

Gene pool

Madonna

Singing, dancing, writhing on floor, shedding clothes – it runs in the family.

Dave

Kid’s a born clown.

Dental DNA

Madonna: See for yourself.

Dave: Gap is more than a clothing store.

TLC

Madonna

By all accounts, she’s a loving, attentive mom.

Dave

Letterman hugging and kissing a kid? Stranger things have happened.