Edinburgh Zoo has admitted it is "really difficult" to tell if a female panda is pregnant as the wait goes on for a possible sighting of cubs.
Edinburgh Zoo said in a statement: "Panda breeding is not a precise science and combined with this each animal has their own individual biology - and Tian Tian is definitely not a text book panda!
“Whilst Tian Tian continues to behave like she’s pregnant and whilst her hormones, behaviour and physical changes suggest the same, we will continue to manage her accordingly; as soon as we know otherwise we will of course announce this.
"To put it into context, there are no experts around the world who can say definitively how long a giant panda pregnancy is."
The zoo can still not confirm whether or not Tian Tian is pregnant.
Edinburgh Zoo's female panda Tian Tian is still looking like she could give birth any day.
Her keepers say she continues to show all the positive hormonal and physical signs of being pregnant and in recent days apart from becoming increasingly sensitive to noise she's become rather grumpy and aggressive.
The panda enclosures will remain closed off to the public for at least the next five days during which time those looking after Tian Tian hope she will have a panda cub.
It may seem rather strange to have such uncertainty surrounding a pregnancy and over such an extended time but panda gestation periods are hard to determine and in the case of Tian Tian experts say she is an especially complicated case.
Her behaviour and blood levels are being monitored 24-hours a day so if she shows any signs of going into labour or having lost her babies keepers will be able to tell straight away.
There's apparently a bet among staff at the zoo that she'll keep us guessing till this weekend. The wait goes on.
A research centre in southwest China has brought 14 newborn panda cubs together for the first time.Read the full story ›
Edinburgh Zoo has closed off their panda enclosures to the public as Tian Tian continues to keep them guessing about her condition.
The female giant panda is still showing signs of being pregnant and in recent days has become increasingly sensitive to noise, prompting keepers to take the decision to stop public viewings of her and male partner Yang Guang.
Despite this move the Zoo can still not confirm whether or not Tian Tian is pregnant. She’s been keeping everyone, even the experts, guessing for almost a month now but this week is likely to provide us with an answer as the normal panda birthing season has already closed.
Her keepers who have been on 24 hour red alert since August 26th will be more glad than anyone that the waiting game is coming to an end.
Officials at Edinburgh Zoo said they are continuing to monitor the hormone levels of giant panda Tian Tian whose pregnancy is "atypical".
In terms of Tian Tian’s possible pregnancy, we’re not out of the game yet although she’s keeping us on our toes.
Her hormones are following an atypical pattern, with lots of rises and dips, which make timings much harder to predict.
We are continually analysing hormone and protein samples and, based on the latest results, our external experts now believe Tian Tian may have experienced her secondary progesterone spike two weeks later than the results previously available suggested.
As Edinburgh Zoo waits to see if giant panda Tian Tian is pregnant they have revealed that her mystery pregnancy is especially difficult to verify.
In a statement the zoo said: "Predicting pregnancy in giant pandas isn’t straight forward and we’re all rapidly learning that Tian Tian is a panda whose behaviour and physiology appears to be more complicated than most."
However the zoo remains hopeful that it could see a panda cub or two and say they will continue to monitor Tian Tian's hormones for more concrete evidence that she is pregnant.
A zookeeper at Edinburgh Zoo, where it is hoped that Tian Tian the giant panda may be preparing to give birth, has said that so far she is "sticking to her normal routine".
Sharon Hatton said that Tian Tian is "doing very well" but that the zookeepers are "not seeing any changes" to suggest that a birth is imminent.
Tian Tian is looking rather relaxed this morning, despite news that she may be about to give birth to the UK's first giant panda baby.
Tian Tian (meaning Sweetie) and Yang Guang (Sunshine) arrive in Scotland from Ya'an reserve in Chengdu, China.
The pair are introduced at Edinburgh Zoo and shown to a specially made "love tunnel", but they only go as far as wrestling.
The zoo launches a “panda-cam” so people across the world can watch the two giant pandas in the run-up to mating season.
After failing to show signs that she is ready to mate, Tian Tian is artificially inseminated.
The zoo's plans to carry out an ultrasound to see if Tian Tian is pregnant are shelved because it is deemed too risky to sedate her.
The Royal Zoological Society of Scotland reveals that hormone changes indicate Tian Tian may be pregnant.