Everyone involved in obstetric practice at the present time will be well aware of the complexities of drug interactions in the mother and fetus, and in the newborn baby. Perhaps themost spectacular manifestations of these drug interactions are those that result in teratogenic effects, but the implications of drug therapy generally in pregnancy range far wider than the hazards of inducing fetal malformation. It must also be realised that there are hazards in withholding some therapeutic agents from pregnant women, and these hazards have to be weighed against the dangers of indis criminate drug...