Panda pregnancy watch under way at National Zoo

      Is she or isn't she? Only Mei Xiang knows for sure.

      WASHINGTON (AP) - Teams of panda fans are keeping a 24-hour-a-day watch on the National Zoo's giant panda, Mei Xiang to see if she might give birth.

      Scientists at the zoo detected a rise in hormone levels in May that could indicate the panda may give birth or end a false pregnancy by early July.Mei Xiang was artificially inseminated twice in January

      . But it's difficult to know whether a panda is pregnant or exhibiting signs of a false pregnancy.

      Since early June, zoo veterinarians have been trying to perform ultrasounds several times a week. The zoo says Mei Xiang has not always been cooperative.

      She is also exhibiting signs of a pregnancy, such as eating less, sleeping more and cradling objects.

      But for now, it's too soon to tell.