It’s springtime in Washington, and that means it’s time to start the annual panda pregnancy watch at the National Zoo. Mei Xiang’s second hormone rise Tuesday could mean one of two things: pregnancy or false pregnancy. It is still too early to determine whether the female panda is pregnant, but the zoo will know in the next several weeks. If she is pregnant, a cub would be expected early this summer. Mei Xiang’s surviving only cub, Tai Shan, was born at the zoo on July 9, 2005. He was sent back to China last year. ?– Natalie Plumb