Brad Pitt and Angelina Jolie conceived their newly born twins in vitro according to a source close to the couple, Us Weekly reported.

The source said that the two super stars wanted so bad to have more children that they chose to conceive through in vitro fertilization.

"They both desperately wanted more babies soon," the source said. The couple’s friend added that the 33-year-old Oscar-wining actress has chosen to conceive through the expensive procedure in order to avoid the stress of trying to get pregnant.

"She could just knock it out," the source said.

The beautiful actress gave birth to twins named Knox Leon and Vivienne Marcheline on July 12 at a hospital located on the glamorous French Riviera. The two parents made clear even before Jolie got pregnant that they wanted to have a lot of children. During an interview on “The Daily Show" last year, Jolie said that she and her husband were having a hard time deciding how many children they wanted.

"It fluctuates between seven and 13 or 14. We kind of feel like, damn it, we're up for the challenge," she said.

The Jolie-Pitt family now has 8 members. The four other Jolie-Pitt children are: Cambodian-born Maddox, 6; daughter Zahara, 3, from Ethiopia; Vietnamese-born Pax, 4, and biological daughter Shiloh, 2, born in Namibia.