Actress Kristen Stewart has gained a significant amount of weight for her small frame, sparking rumors that she is pregnant by ex-boyfriend and "Twilight" co-star Robert Pattinson, whom she dated for three years.

“She definitely has gained weight. However, it is not a bad thing! She was getting to be too thin anyway, and now it appears she is eating, looks healthy, happy and has some curves,” a dietician told Hollywood Life, noting that it appears Stewart, 23, has gained about 15 pounds.

If Stewart is pregnant with Pattinson’s child, it would be shocking considering she cheated on him in 2012 with her “Snow White and the Huntsman” director, Rupert Sanders, 43, and when the affair went public later that year, she and Pattinson split.

But the pair reportedly spent Valentine’s Day together this year. "Even though [Rob] and Kristen aren’t together, he wanted to make sure that she knows she still matters to him,” an insider told Hollywood Life, adding, “Rob is good with stuff like that.”

The actress last month discussed her love life in Marie Claire magazine: “You don't know who you'll fall in love with. You just don't. You don't control it ... If you fall in love with someone, you want to own them -- but really, why would you want that? You want them to be what you love. I'm much too young to even have an answer to that question."

So is she pregnant with the 27-year-old actor's child? One of her friends told Hollywood Life that the rumor is false and that Stewart put on weight for a new movie role: “Don’t get me wrong, Kristen would love to be a mom one day and have little rugrats running around, but not for a while. Her priority right now is her work.”