New research has suggested that some common fertility treatments are no more effective than simply letting nature take its course.
The study of 580 women in Scotland found that couples using the drug clomifene citrate or artificial insemination did not have significantly higher chances of falling pregnant than those not having treatment.
One in seven couples in the UK experience infertility, with around a quarter of these having "unexplained fertility" – where investigations have failed to find abnormalities.
Interventions to help these couples have been used for many years in line with fertility guidelines issued by NICE.
The study divided the women into three groups: one where the women were left to try to conceive naturally, one group given clominfene citrate, and the third group given unstimulated intrauterine insemination.
At the end of the study, there had been a total of 101 live births, with 17% among those women trying to conceive naturally, 14% among those taking the drug, and 23% among those having insemination.
Although those receiving insemination had a higher rate of pregnancy, the researchers said this was not significant enough to be solely down to the procedure.
The research team writing in the British Medical Journal said current guidelines need to be reviewed in light of the findings.