Published results of pharmacokinetic studies (terminal half-life, t½&bgr;; elimination constant, kel; apparent volume of distribution in &bgr;-phase, Vd&bgr;and plasma clearance, CLp) in pregnant and non-pregnant women have been compiled and compared. Most of the data relate to the results of pharmacokinetic studies with 20 drugs in women at full-term pregnancy, i.e. about 40 weeks gestation. A review of these data failed to reveal any consistent overall trend in any of the pharmacokinetic parameters listed and no generally applicable changes in the disposition of the drugs as a result of pregnancy can be characterised. However, pregnancy associated changes appear to be discernable in the elimination patterns of certain drugs, for example, ampicillin, caffeine, diazepam, phenytoin and thiopentone, but the factors producing these changes can still only be suggested.