Freedom of information requests have revealed that pregnant women may not have been given all the facts before taking an experimental treatment to prevent female fetuses from being masculinised as a result of a rare genetic disorder.

Research has provided some evidence that dexamethasone, a drug normally prescribed to relieve inflammation, can prevent girls with a rare hormonal disease from developing male genitalia and same-sex attraction if they are treated as fetuses. But as yet, no clinical studies show that this treatment is safe, says Alice Dreger of Northwestern University in Evanston, Illinois. She claims that researchers have misled an unknown number of pregnant women into taking the experimental treatment without properly informing them of its risks.

Since the 1980s, Maria New of Mount Sinai School of Medicine in New York has studied and popularised the idea of prescribing dexamethasone "off-label" to women at risk of having foetuses with congenital adrenal hyperplasia (CAH). The treatment is now taught as standard practice in medical schools. But because the drug must be given very early in pregnancy before the fetus' gender or CAH status is known, many fetuses are treated unnecessarily. A child with two carrier parents has a one-in-four chance of having the disease, and the treatment only works for girls.

There is little research available on the effects of dexamethasone, which mimics a steroid hormone. And because dexamethasone doesn't cure CAH but only prevents masculinisation of girls, it can be difficult to distinguish possible effects of the drug from other treatments the children receive after birth.

Developmental problems

However, some evidence suggests that the drug may be harmful to foetuses early in development. A recent study of 43 children in Sweden who did not have CAH but had been treated with dexamethasone as fetuses found that 20 per cent of them had some sort of developmental problem. (Journal of Clinical Endocrinology and Metabolism, DOI: 10.1210/jc.2012-1222).

Through freedom of information requests to Mount Sinai School of Medicine, Dreger and colleagues documented what they see as attempts by New's group to circumvent proper patient consent procedures for experimental use of the drug.

The researchers allege that, according to New's grant applications, she skipped important steps in patient consent, promoting treatment as "safe and effective" without informing parents that the claim is controversial. Years later, New's group then followed up a fraction of the patients to ask about side effects.

Because New doesn't have a financial stake in a drug company, the US Food and Drug Administration says that she is free to promote the treatment as safe and effective.

New declined to be interviewed, but in a statement from Mount Sinai, spokesperson Ian Michaels said the claims are "unfounded" because New's practices have previously been cleared by federal agencies and that the FDA has waived the need for dexamethasone to be approved as an "investigational new drug".