Was Nicole Kidman in a movie called the birdcage about a mother grieving the loss of her child?

No, Nicole Kidman was not in "The Birdcage." The film, released in 1996, stars Robin Williams and Nathan Lane and is a comedy about a gay cabaret owner and his drag queen partner who put up a false straight front for their son's future in-laws. Kidman is not part of this film's cast, nor does it focus on a mother grieving the loss of her child.