Ya Ya is Expecting

The Memphis Zoo has announce that the 6 year old female panda, Ya Ya, is pregnant via artificial insemination performed in January. Since panda gestation is approximately 133 days, Ya Ya is expected to deliver in the next month and a half. More information will be available to the zoological team closer to the panda's delivery date. Right now, Ya Ya remains under 24 hour observation. (She is shown at left, with male friend Le Le.)

Pandas are notoriously poor breeders, in the wild and especially in captivity. For a brief review of the difficulties with panda pregnancy, see this article from ScienCentral News. Excerpted without permission:

The scant patterns that have been found indicate that a pregnant panda’s urine hormones track exactly to a non-pregnant panda’s, except for a four- or five-day period about 30 days before delivery.

The change in hormones is thought to correspond to the implantation of the panda fetus, another mysterious event. Called variable delayed implantation, this phenomenon of pandas means that the embryo floats freely in the uterus until, researchers think, conditions for a successful birth are deemed to be favorable and the fetus implants in the wall of the uterus late in the three-to five-month pregnancy. A human embryo implants within days of fertilization.