Panda at Washington's National Zoo births twins, one stillborn This still image from the PandaCam at Washington Zoo shows Mei Xiang during labour. Picture: AFP/Smithsonian National Zoo Source: AFP A PANDA at Washington's National Zoo that has been tending to her squealing newborn cub also gave birth to a stillborn cub that wasn't fully formed and was never alive outside the womb, a zoo official said. Mum still hasn't let zoo staffers get close enough to get a good look at her live cub, but it was squealing throughout and appears to be doing well, Baker-Masson said. The zoo began performing a necropsy on the stillborn cub late on Saturday that they hope will tell them why the cub stopped developing and died in-utero, she said. She compared the planned exam to a race car pit stop, a fast and highly choreographed checkup before reuniting mom and cub. Mei Xiang gave birth to a cub last year that died after just six days. An early exam at the zoo is a change from last year, and staff members made several other changes in preparation for another cub. Mei Xiang's den was altered to allow keepers to get closer to her, and the zoo invited a panda expert from China who specializes in newborns to help out. Zookeepers made two attempts at examining the cub Saturday, but Mei Xiang was cradling the cub and officials were unable to take it for a closer examination, zoo spokeswoman Baker-Masson said. They planned to try again on Sunday. Information collected during the exam will serve as a baseline for future exams. And the DNA sample, either from a swab of the cub's mouth or feces, will be used to determine the cub's father. Mei Xiang was artificially inseminated both with sperm from the zoo's male panda, Tian Tian, and sperm from a panda at the San Diego Zoo, Gao Gao.