The study was funded through grants from the International Dispensary Association (IDA), the Swedish International Development Authority/Swedish Agency for Research Cooperation with Developing Countries (SIDA/SAREC) and the WHO Maternal Health and Safe Motherhood Research/ whose support is gratefully acknowledged.

The research project was planned and conducted jointly by the WHO Action Programme on Essential Drugs, the WHO Maternal Health and Safe Motherhood Research and the International Dispensary Association. The chemical analyses were carried out at the Laboratory of the Royal Dutch Association for the Advancement of Pharmacy in The Hague (O.S.N.M. Smeets, pharmacist, Mrs A.E.E.M. van de Langerijt and Mrs H. Rosing, technicians), whose active and creative collaboration is very much appreciated.

Statistical advice was given by Mrs M. Anker of the Epidemiological and Statistical Methodology unit of WHO, Comments on the draft were made by Mr O.S.N.M. Smeets of the Laboratory of the Royal Dutch Association for the Advancement of Pharmacy in The Hague, Dr A, Mechkovski of the WHO Quality Assurance unit in Geneva, Mrs P. Brudon-Jakobowicz and Ms D.A. Fresle of the WHO Action Programme on Essential Drugs and Dr N. Stjernstrom of the Swedish Medical Products Agency in Uppsala, Their support is gratefully acknowledged.