Around one in three women conceive naturally in the six years after discontinuing fertility treatment, an internet survey of over 400 women has found.
The study team sent online questionnaires to users of a message board on an infertility website (www.ivf-infertility.com) to find out about conception rates after couples stopped IVF or ICSI treatments. They found that 29 percent of women had conceived naturally within six years of stopping treatment.
'Regardless of the outcome of fertility treatments – whether the patients conceived or not – there is about a 30 percent likelihood of conceiving over a six-year period', said lead author Dr Samuel Marcus, consultant obstetrician and gynaecologist at Queen Elizabeth Hospital in London.
Of 403 responses, 34 of the 96 women who did not conceive during the course of fertility treatment subsequently became pregnant, leading to 30 live births. Of the 307 women who conceived during treatment, 84 also conceived again afterwards.
Most of the pregnancies (87 percent) occurred in the first two years after stopping treatment. Women who had gone through more cycles of IVF or ICSI had lower chances of spontaneous conception after stopping treatment. Compared to women with only one to two cycles of treatment, women who had undergone five or more cycles were 60 percent less likely to conceive.
'There is no easy explanation for spontaneous conception after long-standing subfertility,' said Dr Marcus. 'One possibility is that as fertility treatments have become more widely available, they are increasingly utilised for less prolonged infertility and for less severe cases such as unexplained infertility, mild male subfertility and mild endometriosis.'
The researchers also found that couples were not always happily surprised by the unexpected pregnancies. 'It might be imagined that most infertile couples who conceived spontaneously after stopping fertility treatments would be happy,' Dr Marcus told the Telegraph. 'However, some were not, resenting the physical, financial and emotional burden of fertility treatments and a suspicion that previous such treatments were unnecessary.'
Professor Allan Pacey, editor of Human Fertility, where the study was published, said the results could help clinicians when advising patients undergoing fertility treatment. 'It certainly suggests that there remains a reasonable chance of spontaneous pregnancy after fertility treatment has been attempted.'
The researchers acknowledged that there are some limitations in the study, with women who had achieved pregnancy being more likely to respond than those who did not.
According the National Institute for Health and Care Excellence, around one in seven couples in the UK will experience problems with infertility at some time in their lives.