Model Alexis Knapp is allegedly seven months pregnant with Ryan Phillippe's child, having dated him briefly last summer/fall, which we reported yesterday.

The timeline makes sense, but other than that, there was little evidence to go on. Until the actor privately acknowledged it's a possibility, sources say.

Ryan Phillippe will "gladly" take a DNA test to determine if he's the dad, TMZ reports, although he will not do so until the baby is born for health reasons.

There are prenatal paternity tests, but there's a slight risk and The Lincoln Lawyer star does not want to risk the health of Alexis Knapp or her child.

Ryan sources says he will obviously step up and provide all the support necessary for Alexis' unborn baby, provided that the baby is indeed his.

There are reports Ryan and Alexis were boyfriend and girlfriend, but it was brief it so. The couple dated for a while but it was never serious.

Ryan dated Alexis in between Abbie Cornish and current GF Amanda Seyfried. He has two children from his marriage to Reese Witherspoon.

[Photos: Pacific Coast News]