When you've tried everything under the sun, should you look to the stars?

At The Fertility Show in November 2010 Nicola Smuts ran a busy booth offering advice for fertility problems. She spoke to couples about finding the optimum time for trying IVF, about sperm motility and morphology, and about number and condition of eggs. She says she has helped scores of women, many of whom had tried and failed to conceive with IVF in the past, get pregnant. There is nothing unusual about this at a show which is packed with exhibitions from fertility clinics and specialists offering cutting edge medical treatments and advice. Except Smuts is not a medical expert, she's not even medically trained. She's an astrologer.

Fertility astrologers claim that they can pinpoint the best time to try to get pregnant if they know the place, date and time of a women's birth. They say they will diagnose the condition of a woman's fallopian tubes, hormone disorders and psychological problems from astrological charts. And they can recommend specific fertility treatments depending on the position of the planets when you were born.

Could they really have evidence for this? How does Smuts know her intervention led to the women getting pregnant and that this wouldn't have happened anyway? Her website suggests the evidence is thin. Where you might expect to see descriptions of randomised controlled trials there is anecdotal testimony from former patients and instead of links to peer reviewed journal papers there are stories from grateful new mothers in the Daily Mail, Daily Express and Sunday Times.

And these stories are moving. In the Daily Mail in November 2010 Mandy said her visit to the astrologer after seven failed IVF treatments and four miscarriages gave her 'the courage and hope to continue in what is a very hard journey'. Testimonial on Smuts' website say finding the fertility astrologer during the IVF process 'when you are obsessed and desperate and looking for answers' helped couples to conceive. Many of the stories describe a consultation with the astrologer as 'the last resort'. Some women have gotten pregnant after a visit to an astrologer - we just can't tell if there was any correlation.

But so what? Having problems conceiving and going through fertility treatment can be a long, stressful experience with no guarantee of a happy ending. After a while without success, couples might be willing to try anything. It is understandable that people want to find ways of coping with this. A consultation with Smuts costs £150, certainly cheaper than a round of IVF. If couples trying for a baby feel better after speaking to her, where's the harm?

At Sense About Science we know the emotional cost of chasing false hope and the dangers of promotion of something that is not evidence based from having worked with neurological disease charities to help patients make sense of claims and cures for their chronic diseases. This is what the organisation was founded to do, to promote the tools of scientific reasoning for the public. You do not need to be a fertility specialist to ask searching questions about the status of claims regarding IVF and astrology - you can talk about peer review, replication, consensus, stability of the science, levels of confidence and certainty.

But you probably do need to be a specialist to know why scarring on fallopian tubes can only be diagnosed by a gynaecologist, and that only specialist IVF doctors should suggest different IVF techniques. Whilst people must be left to make up their own minds about what treatments to use, doctors and scientists must address misleading claims loudly and publicly, particularly when they are promoted to people most susceptible to their promises such as those struggling to conceive. We shouldn't let people get away with marketing - with misleading claims, optimistic testimonials and pseudoscience - to people who are desperate for some source of hope leaving them unsure about what to try and uncertain where to draw the line.

If you were wondering about the title, this was originally the subtitle of an article by Harris (2008) on using astrology as part of fertility treatment from SRM, the journal of the American Society for Reproductive Medicine.