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Blood flow velocity waveforms in large maternal and uterine vessels were measured longitudinally from 16 weeks gestation onwards until 12 weeks postpartum in 21 singleton pregnancies by duplex sonography. In the maternal carotid artery, time average mean velocity (TAVmean) did not show significant changes. In both the femoral artery and vein, however, significant changes were observed. In the femoral artery, TAVmean and systolic maximum velocities decreased with advancing gestation. In the femoral vein, TAVmean remained constant throughout pregnancy and was lower than postpartum. The resistance index in the uterine arteries decreased with advancing gestation and increased after delivery. Among many factors contributing to femoral arterial blood flow velocity changes in pregnancy, we suggest that a major one is the increase in uterine blood flow. Reduction in venous femoral blood flow velocity and increase in the femoral vein diameter might be associated with the common occurrence of venous disorders in pregnancy.Numerous studies have investigatcd maternal central cardiovascular haemodynamics in pregnancy. Though different measurement methods have been used, and though many results arc controversial, it 1s generally agreed that cardiac

Summary The significance of spontaneous regular uterine contractions during the first stage of labour for fetal oxygenation was studied in 13 patients at term in uncomplicated pregnancies. The drop in transcutaneous (Po2 (tcPo2) recorded from the fetal scalp which usually followed each contraction correlated significantly with the strength of the contraction but generally was less than 2 mm Hg. The mean fetal tcPo2 in the first stage of spontaneous uncomplicated labour was 16·9±5·2 (SD) mm Hg. Suppression of contractions with intravenous fenoterol for 20 minutes did not give a statistically significant change in mean fetal tcPo2. With the administration of supplementary oxygen to the mother during continued suppression of labour, fetal tcPo2 rose significantly to 21·3±4·7 mm Hg. Maternal mean tcPo2 at the same time climbed from 83·2±10·5 to 235·1±97·8 mm Hg. While the mother responded to the infusion of fenoterol with a rise in heart rate from 92·3±15·2 to 122·8±19·7 beats per minute the fetal heart recording showed no significant change in rate or pattern. It is concluded that in the first stage of normal labour no significant impairment of fetal oxygenation is caused by uterine contractions. An important improvement in oxygen supply to the fetus, however, may be achieved in certain forms of fetal distress in labour by the combined administration of β‐sympathomimetics and supplementary oxygen to the mother.

Summary Stroke and minute distance were measured in 12 women in late pregnancy using Doppler ultrasound. In each patient two sets of measurements were made every 2 min for 20 min in the supine and left lateral positions, the sequence of positions being reversed on the second occasion. Within each of the four 20 min measurement periods there were no significant changes with time in stroke distance, heart rate, or minute distance, or in their coefficients of variation. From this evidence there is no justification for delaying the measurement of cardiac output until a 'steady state’is reached. The measurements were influenced both by the sequence and the position in which they were taken, the effects being additive. Overall, stroke distance was 5·1% greater in the left lateral than in the supine position, heart rate was 3·7% less and minute distance not significantly different. Independent of posture, stroke distance was 6·5% greater in the second period of measurement than in the first, heart rate was 3% less and minute distance 2·8% more. In late pregnancy the relative magnitude of cardiac output in the left lateral and supine positions has to be interpreted in the light of a stepwise increase of aortic blood flow with change of posture.

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