Calls for mandatory HIV testing of specific groups are usually dismissed because they are an unacceptable infringement of civil rights. However, since reports in 1994 suggested that maternalfoetal HIV transmission could be reduced by the use of zidovudine (ZDV) [1], there has been a general trend towards viewing pregnant women and newborns as exceptions to the usual opposition to mandatory HIV testing.

In the USA, for example, the 1996 re-authorization of a law on care for persons living with HIV/AIDS included an amendment that appears to allow for, and ultimately promotes, mandatory testing of pregnant women and newborns [2]. Also in 1996, the American Medical Association announced an exception to its general policy of backing voluntary HIV testing; they now endorse mandatory HIV testing for all pregnant women and newborns [3]. In February 1997, hospitals in New York State began mandatory HIV testing of all newborns as part of the Health Department's Newborn Screening Program [4].

Those who propose mandatory HIV testing of pregnant women and infants appeal to established public health precedents of imposing similarly coercive measures in times of crisis. They point, for instance, to mandatory vaccination and quarantine, where expected benefits are perceived to compensate for any loss of autonomy. By introducing mandatory testing of pregnant women and infants, it is hoped that there will be an increase in uptake of treatments which could reduce the risk of vertical transmission and improve the prognosis of any infected newborns.

While mandatory HIV-testing programmes are generally considered unjustifiable on grounds of efficacy alone, advocates claim that pregnant women and newborns present a special case. If such claims are to be seriously considered, evidence of effectiveness must be available. Is this evidence available in the case of pregnant women and newborns?

At present, data regarding the effects of ZDV use on vertical transmission rates are inconclusive and incomplete. In addition, the longterm effects of ZDV use during pregnancy and after birth on the woman and any resulting child are yet to be discovered. At best, the evidence suggests that ZDV could reduce the risk of vertical transmission from around 25% to around 8% [1], but the possibility has not yet been ruled out that this "risk-reducing" measure may not be effective and may prove detrimental to the health of both mother and child. For instance, the effectiveness of a woman's subsequent own treatment may be compromised if she has taken ZDV prenatally. In addition, most children born to HIVinfected women are not infected with HIV themselves; these uninfected infants would be exposed to a drug whose longterm consequences are not known [5].

HIVantibody tests are unable to give a reliable picture of infection in infants younger than 18 months because maternal antibodies, including those to HIV, cross the placenta during pregnancy. As a result, mandatory testing of newborns cannot give an accurate indication of whether the child is infected with the virus; testing can only indicate reliably the mother's HIV status. Mandatory testing of newborns would seem to have less to recommend it than prenatal testing: the opportunity to take measures that may reduce the risk of vertical transmission before and during birth have been missed.

Nevertheless, testing proponents claim that this information, though limited, could notify mothers so that they might refrain from breastfeeding, which may cause an infant to be infected [5]. The question we must ask is whether this chance to persuade HIV-positive mothers not to breastfeed is of such significant benefit that it outweighs the distress which is likely to result from disregarding the autonomy of pregnant women in this way and the possibly harmful long-term effects of treatment given to infants, the majority of whom will be uninfected.

If proponants of mandatory testing are aiming to ensure that as many HIV-positive women as possible accept ZDV prenatally, then unless we are prepared to introduce mandatory treatment of these individuals, there seems no clear indication that the uptake of treatments would be greater than those resulting from, say, a programme of mandatory HIV counselling with an option to be tested.

Although enforced treatment of this kind is not unprecedented, it could only be justified by clear indications of its benefits for the woman and her future child. If, for example, a "cure" were found for HIV, this would be a strong argument in favour of mandatory testing. At present, however, treatments attempting to reduce the chance of vertical transmission may at best reduce the rate of infection by around 15% [1]. At worst, they may cause serious longterm problems for mother and child. Clearly, if compelling evidence was available of a treatment that was likely to reduce significantly the rate of vertical transmission without harmful side effects, then the benefits of knowing one's HIV status would increase. Then also the use of free, voluntary and confidential testing would likely increase, removing the urgency for coercive testing regimes.

Rebecca Bennett, Research Fellow, The Centre for Social Ethics and Policy, University of Manchester, Humanities Building, Oxford Road, Manchester M13 9PL, United Kingdom; Tel: 44161275; Fax: 441612753468; Email: Rebecca.Bennett@man.ac.uk.