Infertile Kerry Horan, 34, gave birth after being given Viagra. After one miscarriage and three failed IVF cycles, Mrs Horan had a scan at the private CARE Nottingham fertility clinic, which showed poor blood flow to her womb. Viagra has vasodilatory properties, meaning target areas receive an increased blood flow, which led Director Dr George Ndukwe to recommend the treatment.

According to The Sun, Dr Ndukwe said: 'It can improve the lining, but can be dangerous and must be taken under supervision'. A second scan showed Mrs Horan's uterus lining had thickened, allowing doctors to implant IVF embryos. During the nine-day treatment she complained of her body going pink and face red. But, after giving birth to 6lb 11oz Grace in December, she said: 'When I finally held Grace it was the most emotional experience. Thanks to Viagra I'm a mother at last!'

In 2000, Bionews reported that three American women and one UK women, all with failed IVF attempts and thin linings, became pregnant and had healthy children after treatment with Viagra. These early successes looked promising, but Dr Richard Kennedy, head of the British Fertility Society, remained sceptical: 'I would like to see more evidence of its efficacy in proper clinical trials before recommending it to patients with this problem'.