Martin J. Whittle

Pregnancy screening by Doppler uteroplacental and umbilical artery waveforms

Doppler waveforms from the uteroplacental and umbilical arteries were studied in 543 unselected women attending an antenatal clinic. Overall, 357 women were studied at 26–30 weeks and 395 at 34–36 weeks; 209 were studied at both gestation periods. Results were not made available to clinicians. There was no difference in outcome of pregnancies between those with normal and abnormal uteroplacental waveforms, but birthweights were significantly lower in those with an abnormal umbilical artery waveform at either gestation. There were no other statistically significant differences between groups. Although the power of the study to detect differences in outcome in this sample size is limited, our findings do not support the introduction of this new technique into clinical practice before sufficiently large randomized controlled trials have shown some benefit.

Effect of nifedipine on Doppler flow velocity waveforms in severe pre-eclampsia.

Comment Our study helps to resolve the uncertainty over the amount and type of exercise needed to diminish the risk of coronary heart disease. In these sedentary women a considerable progressive increase in high density lipoprotein cholesterol concentration resulted from a programme of brisk walking for one year. What are the implications of these changes in blood lipid concentrations for the risk of coronary heart disease? Three studies evaluated prospectively the association between high density lipoprotein cholesterol concentration and subsequent coronary heart disease in women.24 Each reported the concentration to be a strong, negative, irAdependent predictor, an increase of 0-26 mmol/l (10 mg/100 ml) being associated with a 42-50% decrease in risk.34 Based on this evidence, a 54-64% reduction in the number of coronary events over 10 years would be expected if the changes shown here were achieved in a population of women. The importance of our findings is further emphasised by the considerable favourable changes in the ratio of total cholesterol to high density lipoprotein cholesterol concentrations. This ratio was highly predictive of coronary heart disease in Israeli women,4 independent of the total cholesterol concentration. Total cholesterol concentration did not change significantly in the walkers compared with the controls. Nevertheless, at 12 months the mean value was 0 35 mmol/l lower than the baseline value; it had tended to decrease most in those with the highest baseline values. Consequently there might be a therapeutic role for low intensity exercise in patients with hypercholesterolaemia. Exercise will play a part in a population approach to coronary heart disease only if the amount and intensity of exercise needed to confer a decrease in risk are attainable and attractive for large numbers of people. In women high density lipoprotein cholesterol concentration is arguably the most important lipid risk factor.5 We found that it can be modified by a socially acceptable exercise regimen.

Gastroschisis and exomphalos: precise diagnosis by midpregnancy ultrasound

Summary. As part of a regional screening programme for neural‐tube defects the cause of the raised α‐fetoprotein levels was correctly identified in 13 pregnancies with a fetal abdominal wall defect by the 22nd week. Careful ultrasound study identified gastroschisis in seven fetuses and exomphalos in six: the presence or absence of a sac, the course of the umbilical vessels and the abdominal organs involved were the most important diagnostic criteria. Pregnancy continued into the third trimester in five cases complicated solely by gastroschisis and two babies have survived the neonatal period following surgical correction. It is suggested that precise identification by ultrasound of the type and severity of abdominal wall defect and also of the presence or absence of associated anomalies will enable the selection of some babies with gastroschisis or isolated exomphalos which have a good prognosis for survival without handicap.

Maternal and fetal atrial natriuretic peptide levels at delivery from normal and growth retarded pregnancies

Objective To determine whether circulating fetal levels of the vasodilator atrial natriuretic peptide (ANP) are reduced in pregnancies complicated by intrauterine growth retardation (IUGR).

Prepregnancy counselling: experience from 1 075 cases

Objective To assess the activity of a prepregnancy counselling clinic in terms of investigations, counselling, treatment and subsequent pregnancy outcome.

Reappearance of end-diastolic velocity in a pregnancy complicated by severe pregnancy-induced hypertension

A case is reported in which previously absent end-diastolic velocities in the umbilical artery reappeared after treatment in a pregnancy complicated by hypertension. This observation is not consistent with the suggestion that abnormal waveforms are associated with obliteration of the tertiary stem villus arterioles.

Daily variability of umbilical and lateral uterine wall artery blood velocity waveform measurements.

Summary. The daily variability of umbilical artery and lateral uterine wall artery velocity‐time waveforms recorded by continuous wave Doppler ultrasound was determined by making three observations in each of 97 women on different days within a 7‐day period. There were no significant changes in the maximal:minimal Doppler shift frequency (A/B ratio) or the pulsatility index in either artery over the period of study. Common pregnancy complications did not influence the variability of the recordings. The variability of uterine artery recordings was not affected by gestational age between 17 and 41 weeks but the degree of variability of the umbilical artery recordings was greater before 30 weeks. We conclude that after 30 weeks gestation this technique has an acceptable range of daily variability for clinical and research applications.

The effect of intravascular transfusion for rhesus haemolytic disease on umbilical artery Doppler flow velocity waveforms

Summary. To test the hypothesis that an increase in fetal blood viscosity is associated with an increase in resistance to flow, the effect on Doppler flow velocity waveforms of percutaneous umbilical blood sampling and intravascular transfusion was studied in 20 patients undergoing a total of 35 procedures. All but four of the 22 transfusions were associated with a decrease in resistance to flow, as shown by a reduction in the umbilical artery systolic/diastolic ratio, and this also occurred on 10 of the 13 occasions when blood sampling only was performed. These findings suggest that acute changes in blood viscosity following intravascular transfusion arc not associated with an increase in resistance to flow as assessed by Doppler velocimetry. Umbilical blood sampling per se may be associated with a Immorally mediated reduction in placental vascular resistance to flow.

Contractile responses of the human umbilical artery from pregnancies complicated by intrauterine growth retardation

The contractile properties of the umbilical artery to oxygen, U46619 (a stable thromboxane A2 mimetic) and 5-hydroxytryptamine (5-HT) were studied in normal term (> or = 37 weeks) and preterm (< 34 weeks) pregnancies, and in a group of pregnancies complicated by intrauterine growth retardation (IUGR). Isometric contractile responses in the preterm group to oxygen were reduced when compared with the term group, though no differences were found between these groups in the responses to either U46619 or 5-HT. In the IUGR group the responses to oxygen did not differ from gestationally matched normal pregnancies, though among those cases delivered preterm, the finding of absent end-diastolic flow velocity in the umbilical artery prior to delivery was associated with markedly diminished responses to oxygen. These data indicate the development of oxygen-induced contractions in the umbilical artery as pregnancy advances, which may fail to function in the severely growth-retarded fetus.

Phosphatidylglycerol and neonatal mortality and morbidity

In spite of major improvements in neonatal intensive care, mortality and morbidity remain a problem for the very preterm baby. In a study of 168 babies born before 36 weeks the presence of phosphatidylglycerol (PG) as a marker of fetal lung maturity in amniotic fluid or pharyngeal aspirate was associated with a lower requirement for ventilatory support and a reduced incidence of intraventricular haemorrhage and patent ductus arteriosus. It is suggested that the value of the antenatal assessment of fetal lung maturity should Perhaps be reviewed since babies in whom PG is absent appear to be at a high risk of sustaining considerable morbidity.