For the first time, IVF doctors will be able to provide women with helpful statistics about the chances of giving birth based on their age and the number of treatment cycles undertaken.
New research published in TheMedical Journal of Australia shows that women who start the IVF process while aged between 30 to 34 have a 43.4 per cent chance of a live birth after just one cycle, compared to those between 40 to 44, who have a 10.7 per cent chance.
As expected, the greater the number of cycles, the higher the chances of success. For women who begin the process aged 40 to 44, the success rate can climb to 37.9 per cent for the eighth cycle.
"Firstly, we considered a cycle as all fresh and frozen embryos associated with an ovarian stimulation cycle, and secondly, we calculated the probability of success over repeated cycles," said Associate Professor Georgina Chambers from the University of New South Wales.
"This patient perspective over a course of treatment provides women and couples with more meaningful estimates on the likelihood of achieving their first live birth in one, two, five, etc, cycles."
The researchers followed 56,700 women who began IVF treatment in Australia and New Zealand between 2009 and 2012, and tracked them until 2014 or the first IVF live birth.
Live birth rates were calculated for up to eight cycles, stratified by the age of the women.???
The study's findings will be welcomed by the $500 million-a-year IVF industry, which the Australian Competition and Consumer Commission last year put on notice for peddling false or misleading information about success rates.
Clinics generally report success rates per individual cycle attempt, rather than from the overall perspective of a course of IVF treatment. Some clinics have been accused of fudging the numbers.
Now, doctors will be able to provide tailored advice based on cumulative success rates based on complete ovarian stimulation cycles for women undergoing IVF.
The research also shows that for women who start IVF before the age of 45, about 23 to 35 per cent will give up after each complete cycle - mainly because of the psychological and physical demands, as well as costs.
For those who start after 45, nearly half will stop the process after one cycle.
"The average number of complete cycles undertaken in this study was 2.1," said Associate Professor Chambers. "But each individual and couple is different, so they should discuss individual circumstances with their clinicians."
Jo, 45, from Niddrie, Victoria, endured 10 cycles over five years before falling pregnant with her daughter, now four.
Jo, whose IVF journey led her to open an organic baby clothes shop, said even if she was told about the success and discontinuation rates, she would have pushed on. The doctors told her she had a "small" chance.
"The reasons some women can't conceive are so varied and even unknown, so I still would have persevered, still optimistic that I wouldn't have to wait too long," said Jo, who asked for her surname to be withheld.
"You start, thinking that you're not going to go through seven, eight, nine cycles, but it didn't affect my course of action," she continued.
"There's always that percentage of success, it's really a jackpot, but if you don't give it a go, you don't know."
Co-author Professor Michael Chapman, a senior fertility specialist at IVF Australia, said the data will give women "more hope".
"So now I can tell a woman [who is 35]: 'Chances of our first embryo transfer producing a baby are in the order of 32-33 per cent, but it's highly likely you'll have frozen embryos and so by the end of those frozen embryos your chances will be well above 50 per cent," he said.
Official data shows that 33,750 women in Australia and New Zealand undertook 67,700 cycles in 2014, resulting in the births of 12,900 babies. A single cycle can cost up to $12,000.