The big sister in the world's only set of giant panda triplets is about to become a mum.

It is hoped that because Meng Meng is a triplet, she might give birth to a trio herself in September.

There are only 1,864 pandas in the wild, according to the World Wildlife Fund, which considers the animals a vulnerable species, and with only around 300 captivity, three more would be a welcome boost to the population.

"We should say she is more likely to give birth to triplets than other pandas, after all she has the genes, " said Li Guo, an expert at the China Conservation and Research Center for Giant Panda.

Meng Meng now has to eat for two. Credit: AP

Meng Meng and her brothers Shuai Shuai and Ku Ku were born on July 29, 2014 at the Chimelong Safari Park in south China's Guangzhou City.

At the end of 2018, a keeper of the Chimelong Safari Park found that Meng Meng surprisingly showed a sign of being fertile.

She was promptly sent back to her native home in Sichuan and, in mid-May, she successfully mated with a male panda.