A leading British immunologist has sounded a warning over the unnecessary—and potentially dangerous—immunological tests and drugs on offer at many fertility clinics.

Women are placing themselves at risk by taking drugs that suppress the immune system, despite little evidence that the drugs help them become pregnant, says Ashley Moffett of the University of Cambridge.

Many private clinics offer blood tests that claim to detect elevated levels of immune cells called uterine natural killer (NK) cells, which some doctors believe are involved in the immune rejection of embryos during implantation. If the test returns a positive result, patients are then offered treatment to suppress these cells, usually with steroids or intravenous immunoglobulin—at a cost running to hundreds of dollars. One British clinic offering the treatment charges £173 ($345) just for the blood test.

This has somehow slipped through the net of any regulation. Ashley Moffett, University of Cambridge

“This has somehow slipped through the net of any regulation,” Moffett told Nature Medicine. “It is bizarre that women who may be in early pregnancy are exposed to this sort of risk.”

Potential side effects of immunoglobulin treatment include kidney failure, anaphylaxis and, because the drugs are created from pooled blood products, the risk of hepatitis. “Immunoglobulin is not approved for this—women are signing disclaimers,” Moffett says.

Although fertility patients are often desperate to try anything that could potentially help them conceive, there is only scant evidence linking elevated blood levels of NK cells to an increased rate of miscarriage, and some evidence indicating that the cells might in fact be helpful (Nat. Med. 12, 1065–1074; 2006).

Blood levels of NK cells do not necessarily reflect levels of uterine NK cells, and a 2006 Cochrane Review concluded that immunoglobulin treatment “provides no significant beneficial effect over placebo in improving the live birth rate.”

The idea that immunosuppressive therapy can avert spontaneous abortion has found favor with the media and on patient groups online since a 1995 study reported that the treatment is effective in raising pregnancy rates (J. Reprod. Immunol. 28, 175–188; 1995). The lead author of that study, Alan Beer, went on to found a Los Gatos fertility clinic that offers the treatment.

That center's medical director, Edward Winger, declined to comment on the treatment's effectiveness in a clinical setting. Winger admits that the issue has been a source of confusion among immunologists, but says that “the number of NK cells in blood appears to increase in women with a history of recurrent pregnancy loss.”

The treatment is now offered by a growing number of larger, more established fertility clinics, and is largely unregulated. The Human Fertilisation and Embryology Authority (HFEA), which oversees fertility treatments in Britain, only regulates the direct creation and handling of embryos, and not the accompanying drug regimes.

“The get-out clause is that [doctors] discuss it with their patient,” says Raj Rai, a fertility consultant at Imperial College London. “But that is disingenuous, because how is a patient supposed to decide? I don't think it is reasonable to hide behind patient demand.” What's more, Rai points out that immunoglobulins, used to treat a range of immune diseases, are nationally in short supply.