In a controlled study, gastric emptying was measured during the three trimesters of pregnancy and after delivery, using an indirect paracetamol absorption technique. The peak plasma paracetamol concentration, time to reach the peak, and the area under the plasma paracetamol concentration-time curve, were determined. As compared to nonpregnant controls, there were no significant differences in the gastric emptying times of women in the three trimesters of pregnancy and of mothers from 18 h after delivery onwards. Gastric emptying was significantly delayed in mothers within 2 h after delivery (p < 0.01); median (range) values of peak paracetamol concentration, time to reach the peak and the area under the paracetamol concentration-time curve for this group were 12.5 (0.2-30.5) mg.l-1, 120 (30-120) min and 3.8 (0.1-16.6) mg.l-1 x h respectively, and 20.8 (8.6-64.5) mg.l-1, 40 (10-120) min and 13.5 (5.5-28.8) mg.l-1 x h respectively, for the nonpregnant control group (p < 0.01). Repeated measurements of gastric emptying in these women on the second postpartum day showed no significant delay.