Concern by midwives and clients about the potentially harmful effects that pharmacological analgesia has upon the mother's birth experience, coupled with the potential compromise of the fetus (Mander, 1992), is not reflected by the common and widespread use of pethidine within normal midwifery practice. Research based evidence does not support the use of four-hourly regimes of intramuscular analgesia to control acute pain (Royal College of Surgeons and Royal College of Anaesthetists, 1990) Uniform doses of pethidine, often designated by parity rather than the individual requirements, result in intermittent and unsatisfactory analgesia for the majority of women during labour (Moore and Dundee, 1993; Oloffson et al, 1996). The huge client variability in the absorption of drug from the injection site (Austin et al, 1980), is also exacerbated by physiological modification and maternal posture during labour. This affects venous return from the lower extremities (Drummond et al, 1984; Nation, 1980), and therefore absorption and efficacy of the drug. Where a more rapid and predictable response is desired, it is suggested that the injection site should be changed to the deltoid muscle (Lazebnik et al, 1989). Personal reflection, adaptation and integration of this scientific logic into practice has improved the efficacy of intramuscular administration of pethidine significantly. Flexibility of dose and timing, combined with using the deltoid route for injection, has resulted in increased speed of onset and duration of analgesia and reduced total duration of drug given in labour. Pain assessment strategies are also central to this success, as it is argued that it is no longer justifiable or safe to administer a ‘controlled drug’ without evidence of client requirement or assessment, prior to or after administration.