Family source unwraps Ashlee Simpson's Pregnancy Mystery

Is Ashlee Simpson pregnant or not? Earlier this month rumor mills started churning out stories that Ashlee Simpson and her fiancé Pete Wentz are expecting their first child together this fall, however, the celebrity couple have denied those reports till now.

Now, a source close to the pop star’s family has told People Magazine that Ashlee is expecting a baby with fiance Pete Wentz, bassist for Fall Out Boy, and the couple plans to get married next month at a private residence in Southern California. The first Wentz-Simpson offspring is due in October, the source said.

Simpson, 23, is reportedly engaged to Wentz, 28, who initially denied pregnancy reports. "There is a witch hunt for people to be pregnant whenever they get engaged in Hollywood ... I mean we're engaged, that's true, and happy about it," Wentz earlier told MTV News.

But on Tuesday, during a taping of the MTV show TRL in New York, Simpson put off the rumors, saying simply, "Some things you want to keep personal."

And now the People Magazine report says that Simpson is indeed pregnant with Wentz, and the couple is planning to exchange vows in May at a friend's house in La Jolla, Calif., north of San Diego.

Meanwhile, OK! Magazine reports that Ashlee’s older sister Jessica is happy for her sister, but the baby news is not sitting well with her. Jess has yearned for a baby for years, and has said on numerous occasions that she can't wait to be a mom.

"Jessica never imagined that her tom-boy younger sister would have a baby first," the Simpson’s family source said. "It would be very hard for her not to be jealous."

Ashlee and Wentz went public about their relationship a couple of months after they started dating in late 2006. The same year, Simpson, a singer, songwriter and actress, had said in an interview that she was not considering marrying anytime soon. “I definitely want to wait until my late 20s or 30s or whenever the time is right,” she had said.

Of late, the singer had reportedly started joking that between her and her elder sister, Jessica Simpson, she would be the more likely one to get married.

Ashlee Simpson’s two albums received mixed response from the audience, and her new album, "Bittersweet World," is set for release on April 22.