As embryonic stem cell research comes under closer scrutiny in the US, UK and Australia, stem cell scientists are examining the ethics of egg procurement. Since most biologists doubt that an embryo is a human person, the possibility of exploiting women is the only major ethical issue which divides them. One of the misdemeanours of disgraced Korean stem cell scientist Hwang Woo-suk which most disgusted other scientists was that he forced some of his junior colleagues to donate eggs and bought other eggs illegally.

With this in mind, and no doubt its political battles as well, a task force of the International Society for Stem Cell Research has issued draft guidelines. These insist on informed consent for this uncomfortable and potentially fatal procedure. But they leave the door open to remunerating women for the time, discomfort and trouble involved in egg donation. The chair of the task force, Insoo Hyun, of Case Western Reserve University, argues in the leading journal Nature that local ethics committees will act responsibly in setting compensation at a level which constitutes fair compensation, but not an inducement.

Nature's editorial in the same issue is sceptical of Dr Hyun's confidence in ethics committees and points out that the health risks of ovarian stimulation are still not clear. There is some evidence that the fertility drugs used in IVF and egg donation pose long-term risks of cancer. Researchers say that longitudinal studies are needed, as the cancers may not appear until women are in their 50s or 60s. However, as Nature journalist Helen Pearson remarks, "it's unclear who will drive the effort, particularly when private fertility clinics may have little interest in finding out the potential risks of the drugs they use."

Ironically, in the week of Nature's focus on the dangers of egg donation, a healthy 37-year-old woman in the UK died after her eggs were retrieved for IVF treatment. Nita Solanki appears to have succumbed to internal bleeding and renal failure. Her death follows the fatal IVF treatment given to a 33-year-old woman in the UK last year. Temilola Akinbolagbe died of a heart attack caused by ovarian hyperstimulation syndrome (OHSS). IVF is generally regarded as safe, but OHSS does affect about 6% of women to some degree.