Adelaide Zoo's female panda Fu Ni could give birth to a cub in the next few weeks, or just be coming to the end of a phantom pregnancy, keepers say.

Key points: Female panda Fu Ni has been displaying pregnancy-like behaviours

Female panda Fu Ni has been displaying pregnancy-like behaviours Keepers may not know if she is pregnant until she possibly gives birth

Keepers may not know if she is pregnant until she possibly gives birth She could be experiencing a phantom pregnancy

Fu Ni was artificially inseminated on two occasions in mid-September during the yearly panda breeding season and has since been treated as if she is pregnant.

Adelaide Zoo has unsuccessfully tried to breed Fu Ni with her male counterpart, Wang Wang, four times in the past.

Fu Ni has been continually monitored since she was inseminated, with zookeepers conducting progesterone testing and closely monitoring behavioural and physical changes.

But senior panda keeper Simone Davey said there were no definitive tests to confirm pregnancy in giant pandas, as hormonal changes and other typical early-pregnancy symptoms can also be shown during a phantom pregnancy.

She said the only definitive way to confirm a pregnancy was through an ultrasound when a foetus could be seen.

Fu Ni had her first ultrasound with a professional sonographer in November, but has recently been less willing to take part in the examinations.

"In the last week, Fu Ni's attention span has started to wane and she's becoming less willing to participate in ultrasound examinations," Ms Davey said.

"So there's a good chance we won't be able to discover if she's pregnant via ultrasound."

Fu Ni has been observed scratching her rear in a way which keepers consider to be a nesting behaviour.

Next few weeks crucial in determining pregnancy, keepers say

Ms Davey said the next few weeks would be crucial in determining whether Fu Ni is actually pregnant and she said keepers may not find out whether or not she is pregnant until she possibly gives birth.

"Over recent days we've seen a few changes in Fu Ni's behaviour, which based on what we've previously seen in years when Fu Ni has gone through phantom pregnancies, we believe the coming weeks will be the most crucial in discovering if Fu Ni is pregnant," Ms Davey said.

"She's eating less, sleeping for longer periods of time, has become more sensitive to light and sound and is nest making, all signs she's within weeks of giving birth or finishing a phantom pregnancy.

"We hope we'll get the chance to confirm her pregnancy via ultrasound and see her go on to give birth to a healthy cub, but we could also find that after we confirm a pregnancy she may still miscarry or reabsorb the foetus or lose the cub shortly after birth.

"We might also not be able to confirm a pregnancy at all because she continues to be unwilling to take part in ultrasound examinations and she could just simply surprise us one day and give birth or she could not even be pregnant and simply be experiencing a phantom pregnancy."