The zoo says the 34-year-old Sumatran Orangutan went into labour on Thursday night and died just hours after giving birth.

“Everyone at Adelaide Zoo is deeply saddened by this loss, which marks a heartbreaking end to an unexpected pregnancy,” the zoo said today.

The zoo said the cause of death would not be known until a post-mortem examination was completed.

But it said an ultrasound had been performed on Wednesday which revealed the baby had a strong heartbeat and was showing no signs of distress.

Karta had not been expected to fall pregnant as she was on contraception.

She had previously lost six babies since 1995, with most dying shortly after birth.

The zoo said the despite the circumstances of her latest pregnancy it was decided to proceed because Sumatran orangutans were critically endangered in the wild and because Karta deserved the opportunity to become a mother again.

“We were realistic about the challenges faced in the past and we were doing everything in our power to ensure this had a different ending,” the zoo said.

“It has been a very tough 12 hours for everyone at Adelaide Zoo.

“Our focus now is on supporting our dedicated primate team who have been by Karta’s side through this entire journey and of course Karta’s partner, Kluet, our male Sumatran orangutan.”

Karta was born at San Diego Zoo in 1982 and arrived at Adelaide Zoo in 1992.

She has one baby in America.

– AAP