Women should be encouraged to start families earlier as their chances of giving birth "decrease significantly" after they turn 38, according to a new study.
Would-be mothers were 18 times less likely to have a baby through in vitro fertilisation (IVF) at 44 than at 38, when the chances of success are about 24%, doctors found.
And they should be urged to freeze their eggs by the age of 35 if possible, lead researcher Dr Marta Devesa said, adding women over 44 should not to use their own eggs in IVF treatment.
Fertility experts said the findings of the 12-year study showed women needed to be better informed about fertility and had perhaps been misled by "good news stories about celebrities".
Dr Devesa, who presented her report at the European Society of Human Reproduction's annual conference in Lisbon, said: "There is a clinically relevant decline from 41/42 – but the prognosis is really futile from 44 and onwards.
"Women should be encouraged to have families earlier but if you can't change society then we should encourage them to freeze their eggs by 35.
"Indeed women of 44 or older should be fully informed about their real chances of a live birth and counselled in favour of oocyte (immature egg) donation."
The study, carried out at the Hospital Universitaro Quiron-Dexeus in Barcelona, Spain, analysed nearly 4,200 women, who underwent 5,841 IVF cycles, in four groups aged between 38 and 44.
Birth rates shown to fall from 24% for those aged 38 and 39 to 15% for 40 and 41-year-olds, 6.6% for women aged 42 and 43 and just 1.3% for those 44 and above.
Professor Adam Balen, the chairman of the British Fertility Society and a consultant in Leeds, told the Daily Telegraph: "While you hear lots of good news stories about celebrities who may have given birth at an older age, nobody knows the number of celebrities who may not have been able to have babies, either because of infertility or possibly even having had fertility treatment that has been unsuccessful.
"There is always a strong possibility that many of these celebrities may well have sought the assistance of a fertility clinic and may have conceived either with IVF or donor eggs."
In April, former Countryfile presenter Julia Bradbury spoke of her "dream come true" after she gave birth to twin girls Xanthe and Zena at 44 after undergoing five rounds of IVF.