April 10, 2010 12:06 am

The stork knows best

When it comes to finding out whether we are pregnant, it is our bodies, rather than expensive tests, that give the clearest answers

Most couples are aware of the potential hazards of putting off “trying for a baby” – and rightly so. As less than 2.2 per cent of women over 43 who undergo IVF are successful, it’s not as if there is an easy solution on hand for couples who fail to conceive naturally.

But now a host of fertility tests is piggybacking on to this fear that women (and, yes, men) may be leaving it too late. The most established test measures a woman’s follicle stimulating hormone, or FSH. This fluctuates slightly through the menstrual cycle, but rises in the menopause. However, this test is not useful for everyone, as it may not give much more meaningful information beyond what a woman already knows about her body.

Newer types of test investigate different factors. One in particular, Plan Ahead, claimed it could enable you to become “more informed about your fertility”. Although Plan Ahead is not presently on sale in the UK, gynaecologists have told me that some women still use it. It involves three blood tests: one for FSH and two that measure ovarian hormones. However, it cannot be “read” properly if the woman has been off the contraceptive pill for less than a month, or is using contraceptive methods such as the intrauterine system, injections or an implant. In terms of results, you are simply told that your fertility is either “above average”, “below average” or “average”.

The truth is that the only real test of whether or not you can get pregnant is to try. Your blood tests may be perfect, but about one-third of couples trying for a baby have unexplained infertility – all their tests are normal, but a pregnancy remains elusive.

Reproductive Ageing, recently published by the Royal College of Obstetricians and Gynaecologists, shares my lack of enthusiasm for tests like Plan Ahead. The writers comment that AMH (one of the hormones tested in the Plan Ahead kit) is a “good test for ovarian response but less successful in predicting pregnancy”. Indeed, they go on to say that the accuracy of these tests “in predicting clinically relevant outcomes (pregnancy and live birth) is either poor or unknown”. If you have a normal test, you might still have problems getting pregnant, and vice versa.

Our bodies, rather than expensive tests, give us the clearest answers.

Margaret McCartney is a GP in Glasgow

margaret.mccartney@ft.com

Go to Margaret McCartney’s blog at www.ft.com/healthblog;
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