Jennifer Aniston pregnancy rumors after she steps out with rounded stomach

COULD Jennifer Aniston be pregnant?

The 44-year-old star has reportedly had fertility treatment after being engaged to actor Justin Theroux for almost a year.

Oveight she stepped out at We're the Millers premiere in a tight satin dress that left little room for a small bulge to hide.

Her representative Stephen Huvane has denied rumours that she is already expecting, but recent reports claim Aniston has started IVF treatment.

"She definitely seemed to have gained some weight," an eyewitness from the set of Aniston's latest movie Squirrels to the Nuts, which is filming in New York City, told In Touch magazine.

The source added that the Friends actress is aware of her window of opportunity if she wants to have a baby naturally.

"She wasn't as chipper as she has been," a witness said about her on-set mood.

"She knows the clock is ticking - she's well aware of it. She's also done her homework. She's explored all methods for having a baby and knows what her options are with IVF. She's educated herself."

Apparently Aniston is handling the stress of conceiving well. The source added that Theroux is also growing increasingly broody as time goes on.

"There is no desperation. If it's meant to be, it's mean to be," the insider finished.

"Justin didn't always want kids, but his life with Jen changed his perspective on being a dad."