Young adults are putting their future chances of parenthood at risk by their lack of knowledge about their fertility, experts say.
Many young people did not learn about their reproductive health until they were trying to conceive, they said.
The comments come ahead of a conference of leading fertility experts, who are gathering to address how the nation can improve young people's knowledge of fertility and reproductive health.
"Many young people encounter few opportunities to learn about their reproductive health until they try to conceive," said Professor Adam Balen, chairman of the British Fertility Society, who organised the summit.
"One in six couples experiences difficulties in becoming pregnant and the associated emotional and physical impacts cannot be underestimated.
"Our aim is to ensure that the knowledge components of sex and relationship education not only cover how to avoid pregnancies and sexually transmitted infections, but also include information about fertility to help people plan.
"It should be choice not chance - we want to enable young people to make informed choices about pregnancy, whether that choice is to start a family or not."
A new poll conducted to mark the Fertility Summit found many 16 to 24-year-olds found "worrying gaps" in their knowledge of fertility and reproductive health.
While fertility rates for both sexes decline gradually from the late 20s, and can be affected by genetic and environmental factors such as smoking, obesity and nutrition, four in five of those polled thought a women's fertility only started to decline after the age of 35.
And two-thirds of the 1000 young adults surveyed thought men's fertility only started declining after the age of 40.
A third of the young women polled were unaware that being overweight or underweight affected fertility.
And 40 per cent of these women mistakenly believed that having a miscarriage or being on the contraceptive pill for too long could adversely affect fertility.
The findings are being presented at the summit which is being held at the Royal College of Obstetricians and Gynaecologists convened by the British Fertility Society and the College and the Faculty of Sexual and Reproductive Healthcare.
Professor Lesley Regan, a fertility expert and vice-president for strategic development at the Royal College of Obstetricians and Gynaecologists, said: "We believe more should be done as a society to help people who would like to start a family earlier, for example, maternity pay, job security for women with young children, access to flexible working and the cost of childcare are all prohibitive factors to having children sooner."
Dr Chris Wilkinson, president of the Faculty of Sexual and Reproductive Healthcare and a consultant in sexual and reproductive healthcare, said: "We strongly urge governments across the UK to improve the quality of sex and relationship education so young people leave school armed with the necessary facts about not only safe sex, contraception and consent but also fertility and reproductive health."
