The early pharmacokinetics of midazolam were compared in pregnant (active labour, awaiting and during elective Caesarean section) and matched gynaecological patients scheduled to undergo elective hysterectomy, half of whom were given an oxytocin infusion. A standard dose of 5 mg was given intravenously. For the first 15 minutes patients in labour had significantly higher plasma midazolam levels compared to all other groups. This was associated with the largest area under the curve (2 hours), the smallest volume of distribution and lowest clearance. Midazolam when given immediately before Caesarean section, can result in depression of the infant.