Diuretics in pregnancy: a case study of a worthless therapy

In the 1960s and 1970s diuretics were used during pregnancy to prevent and treat toxemia, but this therapy is now widely condemned as ineffective and harmful. The purpose of this paper was to study this example, to learn from it and to help to prevent further such examples. Data sources included selected articles in medical journals and text-books; in Finland drug catalogues, handbooks, unpublished sales data and interviews and questionnaires to physicians; in Sweden drug catalogues and sales data; controlled clinical trials were also analyzed. Analysis of the controlled clinical trials suggested that the whole episode of wide-spread diuretic use in pregnancy could have been avoided, if the available information had been used. A reason for the neglect of the critical information was apparently that the use of diuretics was in accordance with the common medical reasoning which values changes in clinical signs rather than looking for better health indicators. Use of diuretics was condemned in Finland later than, for example, in the United States, and decline in use occurred prior to the warnings in the local literature. Changes in practice seem to have occurred hierarchially and locally: opinions of a few leading obstetricians were crucial and they were rapidly and effectively disseminated to the providers of antenatal care in the domain of each obstetrician. This hierarchial dissemination of information has profound consequences for the attempts of understanding and influencing the prescribing habits of physicians.