The San Diego Zoo's 17-year-old giant panda Bai Yun is pregnant, it was announced today.
The mother of four was subjected to an ultrasound examination on Monday that clearly showed a panda fetus, which was seen moving its paws and tucking in its head, according to the San Diego Zoo.
The heartbeat of a second fetus was also detected, but veterinarians don't know if it will survive because it does not appear to be developing as quickly as the first.
Bai Yun is due to give birth next month, according to Meg Sutherland- Smith, a zoo veterinarian.
"Unfortunately there are still no hormone tests to confirm a pregnancy early on," she said. "We rely on ultrasound images to see the development of a fetus, and based on previous years' observations, we can predict a birth will occur in August."
The father is Gao Gao, according to zoo veterinarians. The two mated naturally in April.
Bai Yun is in an off-exhibit habitat where she has been showing signs of pregnancy, including changes in her hormone levels, nest building and a loss of appetite, according to the zoo.
Bai Yun has delivered four healthy cubs at the San Diego Zoo.
In 1999, her first cub, Hua Mei, became the first giant panda conceived by artificial insemination in the western hemisphere and the first in the country to survive to adulthood.
Hua Mei is now part of a breeding program in China, along with her brother, Mei Sheng, born in San Diego in 2003.
Bai Yun's two other offspring, Su Lin and Zhen Zhen, born in 2005 and 2007, are still at the San Diego Zoo.
