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Ryan Phillippe's ex girlfriend has given birth to a girl. Aspiring actress Alexis Knapp welcomed an 8 lb. baby, Kai, on July 1.

Phillippe, 36, is said to have been by her side in the delivery room at Cedars-Sinai Medical Centre, despite questions surrounding the paternity of the child. “He's waiting for the DNA test to see if he's the father, but he's acting like he is,” a source close to the former couple told In Touch. Phillippe, who recently starred in The Lincoln Lawyer, is expected to undergo a paternity test in the upcoming weeks to determine if the child is his. However, Us Weekly reports that there is no doubt in his mind that he is the father. He has even been photographed accompanying Knapp on her visits to the doctor.

On her part, Knapp, 26, has previously said she doesn't expect Phillippe to take responsibility for the child. “She has never asked Ryan for any help, nor does she expect it,” her representative said.

Knapp, who dated Phillippe briefly last year after his split from girlfriend Abbie Cornish, but ended her relationship with the actor in October when rumors surfaced of him kissing another woman at his 36th birthday celebrations, announced her pregnancy in March 2011.

Knapp’ mother, Marjorie Knapp, also believes the child is Phillippe’s. “She [Alexis] told me right away that it was Ryan’s. They were in a relationship,” she told Radar Online in a recent interview.

Phillippe already has two children, Ava, 11, and Deacon, 7, with his ex-wife, Reese Witherspoon. The couple divorced in 2006 after seven years of marriage, amid reports alleging he was in an extramarital relationship with Cornish, his co-star in the war film Stop Loss. After his split from Cornish, Phillippe briefly dated Knapp before moving on to Amanda Seyfried. The two recently ended their relationship. Witherspoon has also remarried, getting hitched to CAA agent Jim Toth this year.

Knapp has only appeared in small roles in comedy movies like Couple's Retreat and Percy Jackson and the Lightning Thief. She is set to appear in the upcoming Miley Cyrus film, So Undercover.