Many women are risking their chances of being able to have children by leaving it too late, according to Bill Ledger, Professor of Obstetrics and Gynaecology at the UK's University of Sheffield. He told the Daily Telegraph newspaper that women who chose to delay motherhood until their 30s and beyond in order to establish their careers were ignoring the implications this could have for their fertility.

Professor Ledger recommends that women planning to start a family later in life have a fertility test at the age of thirty to help gauge how quickly their fertility is declining. He helped to develop a test, launched in 2006, called the 'Plan Ahead Kit' which works out the number of eggs that a woman has left in her ovaries. From this, it predicts the woman's 'ovarian reserve' for the following two years. Professor Ledger believes the test, which costs £179, could help women make more informed reproductive choices and conceive naturally.

However, Dr Gillian Lockwood, medical director of Midland Fertility Services and vice president of the Royal College of Obstetricians and Gynaecologists' ethics committee, and Tony Rutherford, chair of the British Fertility Society, have both voiced concerns that tests could also create a false sense of security, as egg reserves are not the only factor involved in getting pregnant naturally.

Professor Ledger said that too many women were relying on the availability of IVF as a fallback, not realising that the treatment was not freely available on the National Health Service (NHS) in the majority of cases. Last week a report showed that eight out of ten primary care trusts were failing to provide the recommended three cycles of IVF to women under 40 on the NHS.

Speaking to the Observer newspaper, Dr Mark Hamilton, the leading consultant obstetrician and gynaecologist at Aberdeen Maternity Hospital and former chairman of the British Fertility Society, made further calls for a campaign to raise awareness of fertility issues in primary and secondary schools: 'Sexual health messages focus entirely on avoidance of sex, but this should be coupled with promotion of fertility awareness. We should be teaching everyone, from childhood up, about all the factors linked to fertility potential, and how the huge range of things from lifestyle choices to genetic inheritance can have harmful effects on that potential.'

The average age for women to start a family is now over thirty and has been steadily increasing for decades. Research shows that fertility halves by the age of 35 and declines steadily thereafter.