An Asian elephant at the Ueno Zoo in Tokyo is pregnant in a first for the zoo, which opened in 1882.
Zoo officials said the 18-year-old elephant, named Authi, is expected to give birth around June or July.
Only 10 births of Asian elephants have been reported in Japan, and this would be the first at the Ueno Zoo since it began keeping an elephant in 1888.
Born in 1998 in Thailand, Authi arrived at the zoo in October 2002 along with a male elephant named Artid as a gift from Thailand in celebration of the birth the year before of Princess Aiko, the first child of Crown Prince Naruhito and Princess Masako.
She showed signs of pregnancy after zookeepers made her stay together with the male elephant, now age 19, last October. What appears to be a fetus was observed using an ultrasound in July.
Asian elephants' pregnancies typically take 21 to 22 months.
"We are really glad because we have been working on propagation for a long time," said zoo official Mikako Kaneko. "Since an elephant's pregnancy period is long, we want to take good care of her to let her deliver a baby safely."