Telling the time on a woman's biological clock

According to last week's newspapers, women will now be able to 'tell the time on their biological clocks', and 'see how long they have left to have children' - all for £179. The launch of a new home test kit to help women gauge their egg supply was accompanied by a predictable blaze of publicity. The headlines promised a solution to anyone alarmed by last September's news that women who wait until their thirties to start a family are 'defying nature and risking heartbreak'. It all sounds too good to be true - and unfortunately it probably is, being yet another example of media hype obscuring reality in medical science.

The 'Plan Ahead Kit' measures levels of three different hormones, to assess the number of eggs present in a woman's ovary over the following two years. It appears to be aimed mainly at women in their thirties, who want to know whether they can delay having children for a while longer. But - as many commentators writing in the weekend papers a couple of days later were quick to point out - there are many other factors that can affect fertility, apart from the quantity of a woman's eggs.

Female infertility can be down to endometriosis, past infections or blocked Fallopian tubes, as well as a shortage of eggs. Or, eggs may have chromosomal errors that cause recurrent miscarriages. Even with a sufficient supply of 'high quality' eggs, a fertile man is still required - preferably one whose desire to become a parent coincides with that of his partner. So while a kit to predict ovarian reserve might rule out one source of potential fertility problems, it cannot provide any information on a host of others. For this reason, a 'good' test result could lull women into a false sense of security, and possibly delay any medical treatment that might be required.

For most women, the chances of conceiving - whether naturally or through fertility treatment - drop sharply after the age of 35. But whilst on one page many newspapers urge women to remember this fact of life, elsewhere they carry stories of high profile celebrities seemingly defying nature with ease. These stories are offered as proof that women can 'have it all', whilst omitting details of any fertility treatment they may have had. To take a specific example, in yesterday's Sunday Times, India Knight wrote that 'one of the most active bees in my bonnet concerns the fallacy that if you are a woman it's fine to wait almost indefinitely before you start having children'. Yet in the accompanying magazine, a piece on the birth of twins to the 47-year-old actor Holly Hunter excitedly reported that 'the age for fashionable, first-time motherhood just got revised upwards'.

With such contradictory news coverage, it is perhaps not surprising that some people believe having babies over 40 is entirely possible, and perhaps even desirable - with IVF acting as a panacea for anyone who experiences problems conceiving. The truth is that for most women - those who don't have the money to pay for repeated cycles of fertility treatment using donated eggs - the tick of the biological clock becomes ever more insistent once they turn 35. IVF offers few solutions to this modern dilemma, but it does give infertile couples the chance to become parents. For these people, it is especially critical that nothing delays the diagnosis of any medical problems, and the start of their treatment.