Source: Hugh Hefer Tried, Failed to Knock Up Holly Madison

The friction between Hugh Hefner and the busy stars of The Girls Next Door has now been well documented. But Scandalist has some new gossip today.

The newest rumor is that Holly Madison’s desire for a baby may be just what sparked the recent round of troubles between Hugh and his "#1 girlfriend."

Sources say one of the main reasons Hef and Holly’s relationship began to deteriorate in recent months was unsuccessful attempts to have children.

Despite seeing a whole bunch of Holly Madison nude, and seeking help from medical professionals, Hef wasn't able to put a baby in that. A source says:

“They tried fertility treatments and couldn’t get pregnant. [Holly Madison] really wanted to get married, but even more, she wanted a baby with Hef.”

Two of three Girls Next Door (Holly Madison, Kendra Wilkinson) are said to be dating other people. Bridget Marquardt is still loyal (or better at keeping secrets) we guess.

Earlier this year, Hefner and Madison were reportedly spotted at the office of a prominent Beverly Hills gynecologist who specializes in in-vitro fertilization.

Following rumors of their split, Holly (who has been linked to Criss Angel), said, “I want to be with somebody who I can be married to, and have kids.”

Earlier this week, Kendra Wilkinson, who is also rumored to have a new boyfriend in mediocre NFL player Hank Baskett, confirmed that things are in flux.

“There are lot of changes going on ... people are going through changes," Wilkinson told Us Weekly, adding that she could beat up The Hills cast. "[Hef] is taking it in stride. He keeps it cool, and has a lot of girlfriends around to keep him happy.”