New parents Brad Pitt and Angelina Jolie were so desperate to find the perfect names for their newborn twins, they were still undecided until the last minute.

The actress gave birth to son Knox Leon and daughter Vivienne Marcheline by Caesarian section in Nice, France on Saturday.

But according to the New York Daily News, the couple almost named their newborn son Rex.

A source tells the publication the pair ordered an embroidered play mat from baby website plainmary.com with the name Rex Leon Jolie Pitt - just weeks before the newborns' birth.

Jolie and Pitt are already parents to adopted children Maddox, aged six, Pax, four, three year old Zahara, and biological daughter Shiloh, two.