A. A. Calder

Induction of labour: a comparison of a single prostaglandin E2 vaginal tablet with amniotomy and intravenous oxytocin

Summary. In a randomized controlled study of 100 women of low parity and favourable induction features, induction of labour by means of a single vaginal tablet containing 3 mg of prostaglandin E2 (PGE2) was compared with the conventional method of amniotomy and intravenous oxytocin. Four of the patients (8%) who received the prostaglandin tablet required additional intravenous oxytocin to achieve delivery. The prostaglandin group had a longer mean overall induction‐delivery interval but a shorter amniotomy‐delivery interval than the oxytocin group. One patient in the PGE2 group and two in the oxytocin group required caesarean section. The PGE2 treated patients expressed a higher level of satisfaction with their method of induction, they required less analgesia, had less blood loss at delivery and their babies had a lower incidence of neonatal jaundice.

Upright posture and the efficiency of labour.

The claim that an upright maternal posture during labour improves the efficiency of the uterus to the benefit of both mother and fetus has been investigated in a randomised prospective study. 40 patients undergoing induction of labour were allocated to a recumbent group or an upright group. No differences were found between the groups in the length of labour, mode of delivery, requirements of oxytocic and analgesic drugs, or fetal and neonatal condition. Our data do not support calls to change conventional intrapartum nursing attitudes.

A RANDOMISED TRIAL TO EVALUATE THE USE OF A BIRTH CHAIR FOR DELIVERY

A randomised study of 189 deliveries was conducted to compare performance in the conventional dorsal position with that in a birth chair. There was no significant difference in the length of the second stage of labour, the time spent bearing down, or the need for operative delivery. Overall blood-loss was greater among patients delivered in the chair but more of this group had either an intact perineum or only superficial damage. The condition of the neonates in the two delivery groups was similar.

Spontaneous labour: when should the membranes be ruptured?

Summary. Sixty‐eight patients (32 multigravidae, 36 primigravidae) with intact membranes admitted in early spontaneous labour were studied. Patients were randomly allocated to two groups: group I had an immediate amniotomy and group II were allowed to retain their membranes intact until full dilatation. Early amniotomy significantly shortened the length of labour and reduced the need for augmentation and instrumental delivery. There were no differences between the two groups in fetal outcome as measured by Apgar scores, umbilical arterial and venous blood pH, neonatal jaundice or admission to the special‐care baby unit. Fetal heart‐rate recordings obtained in group I by applying a fetal electrode after amniotomy were of superior quality to those obtained in group II by ultrasound and were more suitable for interpretation.‘Normal’ and ‘suspicious’ tracings occurred equally in the two groups. Our results suggest some benefits from early amniotomy and no adverse effects on the fetus.

Increased platelet reactivity in pregnancyinduced hypertension and uncomplicated diabetic pregnancy: an indication for antiplatelet therapy?

Platelets are thought to play a major role in the pathogenesis of pregnancy-induced hypertension (PIH) (Howie 1977). Increased platelet reactivity may contribute to obstruction of the uteroplacental microcirculation by platelet aggregates and by release of vasoactive substances such as thromboxane A*. Recent studies have shown that in pregnancies at high risk of PIH and growth retardation anti-platelet therapy with low-dose aspirin can prevent development of these complications (Beaufils et al. 1985; Wallenburg et al. 1986; Elder et al. 1988). Consequently much excitement has been generated by the possibility of prevention of these disorders by anti-platelet therapy, although it is difficult to identify patients at high risk of these disorders, especially priniigravidae. Pregnancies in patients with diabetes mellitus have an increased incidence of PIH, and platelet reactivity is known to be enhanced in non-pregnant diabetics, especially those with vascular disease (Halushka er al. 1983). It has recently become possible to study platclet aggregation in whole blood. This is more physiological than the traditional indirect turbidometric techniques using platelet-rich plasma, as it leaves platelets in their natural milieu surrounded hy red cells and white cells which can themselves influence platelet behaviour. In addition it employs i1 sensitive dircct counting technique. There is little information on platelet reactivity in pregnancy using this technique and to our knowledge there has been no previous study assessing platelet Punc-

Posture in labour: patients' choice and its effect on performance

Summary. In a study to assess the influence of maternal posture on the progress and efficiency of labour, 275 parturients were asked to choose between remaining in bed during labour or being ambulant. Among primigravidae in spontaneous labour those who remained ambulant throughout had the shortest labours; they also had shorter labours than others who were only partially ambulant. Analysis of the data, based on original preference, however, suggests that an easy labour allows ambulation rather than vice versa. Radiotelemetry was used to transmit the fetal heart signal in all ambulant patients and provided satisfactory fetal surveillance in both high‐ and low‐risk labours.

Immunoreactive prostacyclin and thromboxane metabolites in normal pregnancy and the puerperium

Summary. Prostacyclin and thromboxane have been implicated in the pathophysiology of several disorders of pregnancy, but there is little information on concentrations of these prostaglandins in normal pregnancy. The aim of our study was to determine the range of values throughout normal pregnancy and the puerperium and to compare this with concentrations in normal non‐pregnant women. Measurement was by radioimmunoassay of prostacyclin and thromboxane metabolites. We observed a significant difference in prostacyclin metabolites in the first trimester. (mean 19·9, SEM 0·96 pg/ml) compared with the normal non‐pregnant group (mean 15·9. SEM 0·68 pghl). There were no significant differences between values in the normal non‐pregnant group and those in the second and third trimester or postnatally. The increase in prostacyclin in the first trimester may be associated with placentation and physiological vasodilation, and insencitivity to angiotensin It seen in early pregnancy. We noted a significant redaction in thromboxane metabolites in the second (mean 133, SEM 14·9 pg/ml) and third (mean 123, SEM 30·7 pg/ml) trimesters and the puerperium (mean 119, SEM 6·3 pg/ml) compared with the values in the normal non‐pregnant group (mean 142, SEM 4·9 pg/ml). This may be due to increased platelet stability or decreased thromboxane synthesis.

Units for the evaluation of uterine contractility

Summary. An improved system of units is proposed for evaluating the contractile activity of the myometrium. Mean active pressure (in kPa) provides the best overall measure of contractility. This measure is broadly compatible with studies quoting‘uterine activity integral’ in kPa s per 15 min, but may be applied to any period of time. Units are suggested for measuring the amplitude, frequency and duration of contractions. It is shown that these are independent variables, and that mean active pressure is the numerical product of these three components.

Fetal heart rate monitoring by telephone. II: Clinical experience in four centres with a commercially produced system

Summary. A commercially produced domiciliary fetal monitoring (DFM) system was assessed in four centres in the UK (Bristol, Glasgow, London and Nottingham) chosen to allow for comprehensive assessment in various settings in many different women. Overall, 825 recordings were made from 368 women (2·24 per woman). There were 56 unsuccessful attempts at transmission (6·8%), most were due to problems with telephone equipment. The system worked most efficiently when a dedicated direct line was used. The data transmission time varied between 40 and 60 s. The median telephone time (including data transmission and conversation) with a dedicated direct line was 7min. Mean acceptance times from the four centres were between 70 and 80%. All recordings with acceptance times of 40% or more were interpretable. Ten recordings were abnormal. The women and midwives were equally proficient at using the DFM system. The DFM system represents an important addition to current methods of fetal assessment. Specific guidelines are outlined.

Blood rheology in pre-eclampsia and intrauterine growth retardation: effects of blood pressure reduction with labetalol.

Blood viscosity (Contraves L S 30) and its determinants were measured in 23 patients with mild/moderate pre‐eclampsia, 10 patients with intrauterine growth retardation and 22 control subjects, matched for age and gestation. Both abnormal groups had a significantly increased blood viscosity at high shear rate (94 s‐1) associated with increased haematocrit. Fibrinogen levels were also increased, but there were no significant differences between groups in plasma viscosity, low shear viscosity (0.94s‐1) or red cell deformability, measured by a low‐shear washed cell system of filtration through 5‐μm pore diameter Nuclepore filters. In the pre‐eclamptic group, measurements were repeated after 1–2 weeks in nine patients treated with labetalol (a combined alpha and beta adrenergic blocker) and in 10 patients treated with bed rest. Labetalol reduced blood pressure but no change in rheology was seen in either group. Control of blood pressure by labetalol does not adversely affect rheology, in contrast to diuretics which are known to cause haemoconcentration and increased blood viscosity.