The Smithsonian National Zoo in Washington DC has a new addition.br On Friday evening, the giant panda family grew by four paws with the birth of a giant panda cub.br The zoo found out that mom Mei Xiang was pregnant about a week ago following an ultrasound.br The 22-year-old giant panda mom gave birth to her new baby and according to zoo officials is happy and healthy.br A neonatal exam will be performed when keepers are able to retrieve the cub, which may take a few days.br The sex of the cub will not be determined until a later date.