Sir

Your recent Editorial, Special Report and Commentary article (Nature 442, 601, 606–608 and 629–630; 2006) focused on the ethics of payments to donors of human eggs for research purposes. There is, however, a source of embryos that would not have been generated specifically for this purpose.

The increasing popularity of clinically assisted reproduction has led to an accumulated surplus of frozen embryos in fertility clinics worldwide. Couples who have attained success in clinically assisted reproduction are often faced with the dilemma of what to do with their surplus frozen embryos: whether to discard them, donate them for research or give them to other infertile couples. When such embryos are donated for research, a pertinent question is whether the donor should receive payment, at least to the extent of reimbursement of storage and medical fees.

Clinically assisted reproduction is an expensive medical procedure that imposes a heavy economic burden on sub-fertile couples in countries where the patient pays. Patients undergoing fertility treatment often use their entire savings for the purpose, leaving scant resources for childcare and education. Hence, it seems fair and ethically justifiable for them to receive reimbursement for part of the medical and storage fees that they had previously paid for their treatment, if they later decided to donate their surplus frozen embryos for stem-cell research.

The portion of medical fees most eligible for reimbursement would be the amount of money directly spent on cryopreservation and storage of surplus embryos in liquid nitrogen. Another eligible component is the pro rata cost of superovulatory drugs, which makes up a substantial portion of the medical fees, particularly in the case of highly purified recombinant gonadotropins. For example, suppose that ten embryos are produced during a prospective donor couple's fertility treatment and six of these are used for treatment. If the remaining four embryos are cryopreserved, stored under liquid nitrogen and subsequently donated for stem-cell research, then the fraction of drug prescription costs reimbursed to the patient would be 40%. The reimbursement could come either from the research grant per se, or from another charity or trust supporting stem-cell research. In this manner, former patients who had previously paid hefty medical bills for fertility treatment would receive an influx of much-needed cash for raising their new family.

The chief ethical objection would be the perception of reimbursement being equivalent to the sale and purchase of the human embryo as a marketable commodity. Nevertheless, it can easily be counter-argued that the payment does not involve embryos donated specifically for research, as patients would be reimbursed only for money that they had already spent in generating surplus frozen embryos in case of initial failure in attempting clinically assisted reproduction. Because patients have to qualify for assisted-reproduction programmes, the issue of 'undue incentive' for egg donation does not arise. Of course, it is essential that patients should receive professional counselling so that they can make a well-informed decision, before any reimbursement is given.