Hopes are rapidly diminishing that America's giant panda Ling-Ling, expected to give birth last weekend after showing strong signs of imminent motherhood, is indeed pregnant.

The National Zoo's Panda House was closed to the public last Friday after Ling-Ling began grooming herself and cradling apples, and zookeepers noted a strong drop in the level of the hormone pregnanediol in her urine, said Dr. Robert Hoage, a zoo spokesman.Ling-Ling has not given birth, and the hormone level and behavioral changes have continued to diminish this week, Hoage said.