The National Zoo in Washington is checking for signs of a panda’s pregnancy. Experts at the zoo have identified a rise in hormone levels in its adult female, Mei Xiang.

It is known that once these levels start to increase, the panda delivers after a gestational period of 40 to 60 days. At times this period can also symbolize a pseudo or false pregnancy. Pseudo pregnancy is a common phenomenon in pandas and other bears.

Janine Brown, who is a reproduction expert at the National Zoo, evinces that a panda's level of the hormone progesterone increases when the bear first goes into heat.

It increases for the second time 70 to 100 days after the first phase. Experts are of the opinion that it is during the second increase in hormonal levels if the panda is pregnant, the embryo implants in the uterus.

According to Brown, the second phase of hormonal increase in Mei Xiang started around the middle of last month. She also conjectures that the panda’s breeding season will come to an end around early May.

Brown remarked, "If we don't see a cub at that point, we just assume she was pseudo pregnant".