Tian Tian should have gone into labour last weekend (August 30-31), experts say.

Experts unsure whether Tian Tian will give birth as she passes her due date

"Will she, won't she?" is the question on panda experts' lips this week, as Edinburgh Zoo's female panda Tian Tian appears to have passed the last date on which she should have given birth.

For more than a year, Britain's animal lovers have waited with bated breath to find out if the panda will finally give birth to a cub.

Sadly, it looks as though they may once again be disappointed as she has passed the last date that she should have gone into labour.

Tian Tian was artificially inseminated in April for the second time after her first pregnancy last year ended with a suspected miscarriage. Experts took the decision to artificially inseminate the panda after attempts to mate Tian Tian and the zoo's male panda Yang Guang proved unsuccessful.

Now, experts at the zoo are afraid "something might be amiss".

In a statement, director of giant pandas at Edinburgh Zoo, Iain Valentine said: "As you are all probably aware, giant panda Tian Tian is now past her due date and the evidence suggests that this may be bad news.

"She is still displaying some of the behaviours of a pregnant panda, but the scientific data from the urine analysis of her hormones is becoming more atypical."

Mr Valentine stressed that Tian Tian's pregnancy was "definitely not a pseudo or phantom pregnancy" and she has had "the profile of a pregnant panda likely to carry to full term".

The zoo is working alongside some of the world's best panda experts, who are in agreement that data extracted from scientific analysis of the panda's hormones and urine proteins was "a text book example of what we wanted to see".

At the end of last week, however, one or two results from hormone tests were atypical.

"Although it is still very new, the scientific data does suggest that the last point she should have gone into labour was over the weekend, unfortunately this did not happen," Mr Valentine added.

As Tian Tian's progesterone levels have not yet returned to base, there is still a chance that the panda may give birth to a live cub, experts have said. She will continue to be monitored closely and more information will be available towards the end of the week as her cycle comes to an end. For now, the panda enclosure remains closed.

Image courtesy of the Royal Zoological Society of Scotland