When zookeepers discovered an endangered Asian elephant was pregnant, they were overjoyed.
Unfortunately animal rights activists were less happy.
They say they are "shocked" Taronga Zoo has allowed a nine-year-old juvenile to conceive, claiming it is "the equivalent of allowing your 12-year-old daughter to become pregnant". Scroll down for more...
'Gymslip mum': Thong Dee is five months pregnant, which animal lovers say is too young
"It is completely irresponsible," said Erica Martin, Asia Pacific Director of the International Fund for Animal Welfare.
The Sydney zoo, which is famous for its views over the city's harbour and Opera House, proudly announced yesterday that Thong Dee is almost five months into her 22-month pregnancy.
In a statement, director Guy Cooper called the occasion "an historic event" and said the birth would be the first by a captive elephant in Australia.
The zoo even released several ultrasound images, which show a 4ins foetus with the beginnings of a spine, front and hind legs - although a spokesman stressed it is too early to tell whether it is male or female. Scroll down for more...
Ultrasound: The calf foetus is 10cm long with the beginnings of a spine, front and hind legs
But animal rights groups have attacked the zoo, claiming that there is very little conservational benefit to Thong Dee becoming pregnant.
The young elephant faces "considerable health risks", they added.
Bidda Jones, chief scientist with Australia's Royal Society for the Prevention of Cruelty to Animals, said: "Calves born in zoos have double the mortality rate in the wild. This pregnancy will put both mother and calf at great risk. Still birth, infanticide and rejection of calves are the main causes of infant mortality.
"Thong Dee's age and lack of maternal and social experience make this pregnancy very risky.
"Under captive breeding plans, elephants should be at least 11 years old before having children."
But the zoo insisted last night that all four of its female elephants - Porntip, Pak Boon, Tang Mo and Thong Dee - have been assessed by reproductive specialists from Germany and were found to be eligible for breeding. Scroll down for more...
Youngest mum on the block: Thong Dee with her older family members at Taronga Zoo
"The well-being of all animals in our care is of paramount importance," Mr Cooper said. "Our breedingprogrammes are carefully managed to exacting standards that ensure our specialist staff employ the latest advice and scientific research."
The youngest Asian Elephant to become pregnant in a European zoo was only five and a half years old, he added.
It is not the first time the zoo has caused controversy.
In November 2006, animal welfare groups criticised a decision to import eight Asian elephants - including Thong Dee - from Thailand.
Several groups staged demonstrations protesting against the elephants' captivity.
Animal lovers in uproar as Australian zoo celebrates 'gymslip mum' elephant | the Daily Mail