Public Release: 

Fertility experts urge clinics to consider 'natural cycle' IVF instead of routine use of ovarian stimulants

European Society of Human Reproduction and Embryology

A team of UK fertility experts wants IVF clinics to consider taking advantage of a woman's natural cycle during infertility treatment instead of routinely using drugs to stimulate ovaries into producing extra eggs.

A study published today (Wednesday 31 January) in Europe's leading reproductive medicine journal, Human Reproduction*, has found that for the majority of women the chances of pregnancy are just as good if doctors rely on the woman's natural menstrual cycle.

The researchers' view is that, in 60% to 70% of cases, a series of treatment cycles without using ovarian stimulation would be safer, less stressful and mean fewer multiple births. It also costs only a fifth of the price of current practice and would bring IVF within the reach of more childless couples worldwide and enable countries that state-fund IVF to help more women.

Dr Geeta Nargund and colleagues reached their conclusion following a study of 181 treatments in 52 women at the Assisted Conception Unit at King's College Hospital, London. All the women had treatment based around their natural menstrual cycles.

They were found to have the same chance of having a baby after an average of three to four cycles of treatment as women undergoing conventional drug-stimulated treatment - about a third (32% as against 34%).

The first test-tube baby - born in 1978 in England - was the result of normal menstrual cycle IVF treatment, but the practice was pretty well abandoned with the onset of extensive use of hormonal drugs to stimulate the ovaries into producing more eggs per cycle. This new study is the first to establish that basing treatment on a woman's natural cycle can achieve comparable results with those of drug-stimulated cycles.

Dr Nargund, who now directs the fertility centre at St. George's Hospital, London, said: "We've demonstrated that it is an effective and potentially cost-effective option for certain groups. With a trend now to reducing the number of embryos transferred, our study must open the debate as to whether a series of natural cycle treatments should become a mainstream conception technique for female infertility."

The women most suited are those with reasonably regular menstrual cycles who ovulate normally but who have problems with their fallopian tubes, or those couples where the reason for the infertility is inexplicable. It would not be suitable for women who don't ovulate or who have very erratic menstrual cycles and probably also not for couples undergoing ICSI (the injection of a single sperm into the egg), although research into its feasibility for ICSI is to be carried out.

Dr Nargund said that ovarian stimulation posed significant problems. Most cycles of treatment in the UK, for example, were not funded by the National Health Service and the additional bill for drugs and extra procedures could add significantly to the cost for couples. Disposal of extra embryos generated could cause ethical and religious dilemmas while problems related to multiple pregnancies still occurred and added significantly to the number of premature births and subsequent costs in neonatal care.

Analysis of costs of the two methods showed that, in the UK, natural treatment cycles could be offered at 23% of the costs of stimulated cycles, offering savings of at least between £4,769 and £9,587 per pregnancy.

Dr Nargund said: "Ovarian stimulation leads to up to 5% of women developing ovarian hyperstimulation syndrome, which is a life-threatening condition that affects nearly 1,500 women annually in the UK and 15,000 worldwide. Natural cycle treatment avoids that risk. There are also some anxieties that long-term use of repeated ovarian stimulation may increase the risk of ovarian, endometrial and breast cancer, although that issue has still to be resolved through further research."

Another benefit of natural cycle treatment is that it can be compressed into consecutive cycles whereas repeated stimulated cycle treatment has to be spread over several months or even years because of the need for ovaries to recover. "This aspect should not be underrated as long-drawn out treatment can sometimes cause considerable stress to couples, who may find themselves putting their lives on hold as a result," said Dr Nargund.

One of the advantages of stimulating the ovaries is that treatment can be scheduled to avoid retrieving eggs at the weekend. But, by giving the drug indomethacin (similar to Nurofen) to those likely to ovulate at the weekend the researchers were also able to avoid weekend egg retrieval, as they have established that indomethacin effectively delays the rupture of the ovarian follicle.

"Of course, we are not saying there are no advantages to ovarian stimulation even in those women who could benefit from natural cycles. Multiple egg collection does provide spare embryos for freezing and that will be an important consideration for some women," said Dr Nargund.

"However, I hope that IVF units across the world will look at this research very carefully and accept that it is now time to offer natural cycle treatment as the main line of therapy where it is clinically appropriate."


* Cumulative conception and live birth rates in natural (unstimulated) IVF cycles. Human Reproduction. Vol. 16. No 2 pp. 259-262.

1. Full embargoed text of the paper with participating research teams can be found from 9am Monday 29 January on website:
2. Human Reproduction is a monthly journal of the European Society of Human Reproduction and Embryology (ESHRE). Please acknowledge Human Reproduction as a source. ESHRE's website is:
3. Printed text available on request from Dr Helen Beard, Managing Editor. Tel: 44-0-1954-212404 or email:

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