Children should have fertility lessons from age 11 to warn of the dangers of starting a family too late, a leading doctor in the UK has said.
Adam Balen, chairman of the British Fertility Society, said pupils must be told about the best age to have a child when they are taught about contraception in sex education lessons.
He will tell a summit that many girls are unaware how quickly their biological clock speeds up as they get older - and that the problem is exacerbated by celebrities who parade "miracle babies" in their 40s but hide the fact they have had expensive fertility treatment.
Professor Balen will add that the number of childless middle-aged women has doubled in two generations and that the lessons could spare tomorrow's women from the "profound heartache" of infertility.
Boys should also take part in the classes as founding families is "all about couples". The academic, making the call on behalf of the BFS's Fertility Education Taskforce, said fertility lessons should be part of the national curriculum.
"Young people need to be informed that fertility declines as you get older and getting pregnant doesn't happen easily," he said. "Young people should be supported to establish relationships, establish careers and establish families - not one to the exclusion of the other."
His warning comes as growing numbers of women are putting off motherhood. They are now more likely to have a child when over 35 than under 25. The number of children born to women aged 40-plus has trebled in the past 20 years.
But many who wait are not so lucky and IVF is not an insurance policy. Even the best fertility clinics have only a 50 per cent success rate. Those who do become pregnant at a later age have a higher risk of miscarrying and having a baby with Down's syndrome.
Professor Balen said young people have a limited awareness of the facts. They are also being given a false sense of security by celebrities who trumpet the fact they have had babies late in life without making it public that they have used IVF, donor eggs or surrogacy.
On Friday, fertility doctors and family planning experts will meet at the Royal College of Obstetricians and Gynaecologists to discuss plans including educational materials for teachers in sex and relationship lessons that already run from the age of 11.
Trained student volunteers could also go into schools and give out advice, including facts on how quickly fertility declines and how it is affected by smoking, drinking and weight.
Professor Balen said couples should start trying for a family by their late 20s or early 30s. Leaving it later could cause "profound emotional heartache, huge distress, anxiety and uncertainty".
The professor, a consultant in reproductive medicine at Leeds Teaching Hospitals NHS Trust, said: "This is not something that young people think about. We are not trying to scare them, we want to inform them."
Professor Geeta Nargund, medical director of Create fertility clinics, who will take part in Friday's summit, said: "Contraception and conception are two sides of the same coin. This doesn't mean we are trying to tell women to have babies when they are young. It is about raising awareness and giving them the knowledge they deserve and that is missing at the moment."
Norman Wells, of the Family Education Trust, said: "So much sex education has placed such a strong emphasis on how to avoid pregnancy, that it has frequently presented a very negative image of childbearing... and some, to their cost, are leaving it too late."