From the Zoo:
“Scientists at the Smithsonian’s National Zoo have confirmed a secondary rise in urinary progesterone in Mei Xiang. The rise indicates that she will experience the end of a pseudopregnancy or give birth to a cub in 40 to 55 days.
Since the artificial inseminations the Zoo’s panda team has monitored Mei Xiang closely. Zoo scientists will continue to monitor her hormone levels through daily hormone analyses. Veterinarians are conducting ultrasounds regularly as Mei Xiang chooses to participate in them, to monitor changes in her reproductive tract and evaluate for evidence of a fetus. Giant panda fetuses do not start developing until the final weeks of gestation, making it difficult to definitively determine if there is a pregnancy. It may be too early to detect a fetus.
Keepers are also monitoring Mei Xiang’s behavior closely. She has begun nest building which is consistent with a rise in urinary progesterone. The area of the David M. Rubenstein Family Giant Panda Habitat closest to her den will close any day to provide quiet for Mei Xiang, who shows extra sensitivity to noise during the final weeks of a pseudopregnancy or pregnancy. Panda fans can watch Mei Xiang on the upgraded panda cams, sponsored by the Ford Motor Company Fund. The cams in Mei Xiang’s den, where she will be spending much of her time over the next month, have also been replaced with high-definition cameras.”