Quote from : Star Wars: Episode III - Revenge of the Sith Movie

[Padme is in the medical center]
GH-7 Medical Droid: Medically, she is completely healthy. For reasons we can't explain, we are losing her.
Obi-Wan: She's dying?
GH-7 Medical Droid: We don't know why. She has lost the will to live. We need to operate quickly if we are to save the babies.
Senator Bail Organa: Babies?
GH-7 Medical Droid: She's carrying twins.