Summary A combination of pulsed echo and continuous wave Doppler ultrasound was used to obtain blood flow velocity signals from the umbilical arteries of 18 normal patients from the 16th until the 40th week of pregnancy. Audio frequency analysis of these signals yielded fetal blood velocity waveforms. Analysis of these waveforms demonstrated that the placenta is an organ of low vascular resistance and that placental resistance to blood flow declines with advancing gestational age in normal pregnancy.

Summary The characteristics of normal labour in 1306 white, Asian and black parturients have been established following a prospective study of 3217 consecutive labours. Asian patients were found to be of significantly shorter stature than white or black women (p<0.001) and their infants significantly lighter than those of white (p<0.001) and of black (p<0.05) women, and a low positive correlation was found between maternal height and infant birth weight. The mean duration of the first stage of labour, taken from the time of admission to the labour ward, was 5‐6 hours in primiparae and 3.7 hours in multiparae. The mean durations of the second stage of labour were 41.5 and 17.4 minutes respectively. The correlations between the duration of the first and second stages of labour were too low to be of value in patient management. Similar low correlations were found between the duration of the second stage of labour and both infant birth weight and the Apgar score at one minute. Cervical dilatation‐time curves, constructed with reference to the cervical dilatation found on admission to the labour ward, revealed no significant differences in the progress of normal labour in the different racial groups.

A study of 1955 spontaneous labours is presented relating progress and outcome to the presence of a lumbar epidural block in 282 of these patients and to the need for oxytocin augmentation in 427. Graphs for cervical dilatation starting at admission to hospital were constructed for normal and dysfunctional labours of spontaneous onset. Patients requiring augmentation of labour had a lesser cervical dilatation on admission to hospital, a longer first stage, more instrumental deliveries, more Caesarean sections and a greater number of babies with a low Apgar score. An epidural block had no effect on either the duration of first stage or the rate of cervical dilatation but was associated with a 20-fold increase in rotational forceps delivery and no increase in Caesarean section rate. With an epidural block there was no increase in the number of babies with cerebral irritation or low Apgar scores and there was a statistically significant improvement in the Apgar scores of babies of mothers in augmented dysfunctional labour who had an epidural block. The incidence of rotational forceps delivery in patients with an epidural block could be reduced with safety by allowing such patients to have a longer second stage before considering interference purely for delay.

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