Brad and Angelina had IVF

Brad and Angelina conceived twins through IVF, claim US sources

Brad Pitt and Angelina Jolie turned to fertility treatment to conceive their newborn twins, Knox and Vivienne, according to US reports.

Hollywood's golden couple put mother nature to one side and took matters into their own hands in order to expand their ever-growing brood.

One source told US Weekly magazine: 'They conceived through in vitro fertilization. They both desperately wanted more babies soon'.

According to LA-based fertility expert Dr Arthur Wisot, the chance of having fraternal twins at Angelina's age (33) naturally is less than 1%, but with IVF, the chances are 25%.

Angelina opted for the treatment, which set Brad and Ange back $12,000, so that 'she wouldn't have to deal with the stress of trying to get pregnant. She could just knock it out,' the source revealed.

The actress confirmed her desire to increase the size of her family quickly in a magazine interview last year saying: 'If we're going to have 10 kids, we'd like to raise them while we're young'.

FOR MORE ANGELINA JOLIE PICTURES CLICK HERE