No other details have been released yet about the baby or the birth.
Last December, Knightley, 30, joked about going into labour during an appearance on “The Ellen DeGeneres Show.”
“My plan is to get it out,” she said, laughing. “[I’ll] drop it out, keep working. Pick [the baby] up, that’s my plan. That would be wonderful for television, but not so good for me.”
Knightley and Righton, 31, got married in May 2013 in France.