10/15/2007 at 01:00 AM EDT
is no stranger to deflecting pregnancy rumors. "Yes, this would be my 30th child," the singer joked when asked about the most recent round during a Sept. 20 interview with the U.K.'s Observer Magazine
. But since an eyebrow-raising Just Sweet fashion show in N.Y.C. Sept. 11, when the singer hit the runway in a clingy green dress that highlighted what appeared to be a baby bump, there has been a drumbeat of new expectations.
Lopez's rep could not be reached, while Anthony's said, "No comment." And it's true that Lopez could simply be following the season's wave of babydoll dresses. But at the opening tour stop Sept. 28 at Atlantic City's Trump Taj Mahal, Lopez commanded the stage in four flowy outfits, including a gold cape dress, which prompted this kind of verdict from concertgoers: "I think she's pregnant," says Melody Charen. "To come out with loose clothing like that is not her!" Designer Roberto Cavalli, who created her tour costumes, says Lopez was "very involved in the design process, from start to finish," and "wanted to be comfortable enough to dance." Though clearly not with her usual intensity: As she grooved onstage in Atlantic City, her moves seemed especially tame in light of the montage of her classic, cardio-heavy music videos flashing behind her.
Lopez, 38, may be taking pains to hide a bump from the public, but a source tells PEOPLE that she's already shared the happy news with her friends. The source heard from a mutual friend, "I saw Jenny in New York very recently and she told me she is finally pregnant." Yet her father, David Lopez, told PEOPLE Sept. 18, "She hasn't said anything to me." The singer's stance does follow in the baby steps of other recent moms-to-be (see box) who have tried to keep their news under wraps. Or perhaps, like many expectant mothers in their late 30s, she may not want to reveal the pregnancy too soon. Then there's the issue of timing. "Jenny doesn't want to [distract from] any part of the tour that she doesn't have to," says a family friend. "She may wait until mid-October when she is showing more." Finally, she and Anthony, 39 (who has three children from past relationships), may just like things low-key. "Keeping the pregnancy a private matter for as long as possible [would] alleviate stress," says another friend of the duo who hasn't heard any baby news. "She would do whatever she feels would be best for the child." And, of course, it keeps 'em guessing.