Delivery after caesarean section: review of 2176 consecutive cases.

A total of 2176 consecutive patients who had had one previous caesarean section were studied retrospectively. A repeat elective caesarean section was performed in 395 (18.2%). Labour started spontaneously in 1363 patients, 301 of whom were given oxytocin to accelerate inert labour, and was induced by amniotomy and infusion of oxytocin in 418 women; 1618 of these 1781 patients (90.8%) delivered vaginally. Patients who had had a previous vaginal delivery were more likely to deliver vaginally again. Those women in whom the initial caesarean section had been performed during labour before the cervix was 4 cm dilated were less likely to deliver vaginally than those who had progressed further in labour or those who had had an elective caesarean section. Similarly, those who received oxytocin to stimulate inert labour were more likely to require a repeat caesarean section than those who did not. The uterine scar ruptured in only eight (0.45%) of the 1781 patients allowed into labour. The risk of rupture of the scar was not increased by the use of oxytocin alone either to induce or to accelerate labour. The combination of oxytocin to accelerate labour and epidural analgesia to provide pain relief, however, was associated with an increased incidence of scar rupture. Labour may be safely allowed in women who have had a previous caesarean section, most of whom will deliver vaginally. Induction of labour does not increase the risk of either a repeat caesarean section or rupture of a uterine scar.

Induction of labour, birthweight and perinatal mortality by day of the week.

There were 66,974 births at the three largest Dublin maternity hospitals in the years 1980-1982. Data on numbers of spontaneous and elective births, birthweight and perinatal mortality were analysed by day of the week. Perinatal mortality rates were highest on Wednesdays and Saturdays. The rate on Sunday was close to average. The largest number of perinatal deaths per day occurred on Wednesdays and the smallest on Sundays. Significant variations in mortality rates and percentage low birthweight were found among the 19% of infants who were born electively, but not among those born after a spontaneous onset of labour. High-risk pregnancies, including many with intra-uterine fetal death, were induced in large numbers from Tuesdays through Saturdays with a peak on Wednesdays. Low risk cases were induced mainly from Monday through Fridays with a peak on Fridays. The pattern of perinatal mortality through the week followed closely that of the risk status of pregnancies delivered electively. The results indicate that the pattern of perinatal mortality by day of the week of birth was determined by a highly organized weekly routine of selective elective delivery.

The assessment of the feto-placental circulation with continuous wave Doppler ultrasound.

Continuous wave Doppler ultrasound was used together with B-mode real time ultrasound to study feto-placental blood flow in utero. The results of 887 examinations on 221 patients are presented. The fetal heart rate acceleration slope and pulsatility index (P.I.) of the audiofrequency ultrasound display were analysed. There was a significant reduction in fetal heart rate (P less than 0.001) and P.I. (P less than 0.001) with advancing gestational age in normal pregnancy. In contrast, in retarded intrauterine growth a significant increase in P.I. values was observed in 77% of patients.

Continuous wave Doppler ultrasound in evaluation of cerebral blood flow in neonates.

The cerebral circulation of 25 normal term infants was investigated using continuous wave Doppler ultrasound. Serial blood flow velocity signals were obtained from the common carotid and anterior cerebral arteries during the first week of life. The records were processed using a frequency spectrum analyser to provide cerebral blood velocity waveforms. The pulsatility index (PI), A/B ratio, and rise and fall slope of the waveforms were calculated. The results indicated that cerebrovascular resistance was raised appreciably on day 1 of life compared with later in the first week. In 18 of 25 infants (72%) there was no continuous carotid blood flow in the first hours of life. We suggest that the human cerebral circulation adapts to the process of birth in a similar fashion to that of animal models.

Evaluation of cerebral blood flow in the normal neonate by Doppler spectrum analysis.

Continuous wave Doppler ultrasound has seldom been applied to the evaluation of the cerebral circulation of the newborn infant. Twenty-five term infants were studied and records taken from the common carotid and anterior cerebral arteries during the first week of life using a bidirectional Doppler instrument. The best Doppler signals obtained were audiofrequency analysed and sonagrams recorded. Analysis of the carotid sonagrams revealed a mean Pulsatility Index (PI) on the first day of life of 0.98 compared to 0.88 on Day 2 (p less than 0.001). An unexpected finding was the absence of continuous carotid blood flow in the majority of infants in the first hours of life. The PI on subsequent days did not differ significantly from Day 2. The PI of the anterior cerebral arteries on Day 1 was significantly elevated (p less than 0.001) compared to Day 2 and subsequent days. The significance of these findings and their importance in the further evaluation of pathological cerebral states in the neonate, especially birth asphyxia and intracranial haemorrhage are discussed.

Fetal blood velocity waveforms in uncomplicated labour.

A combination of pulsed echo and continuous wave Doppler ultrasound was used to obtain blood flow velocity signals from the umbilical arteries of 10 patients during uncomplicated spontaneous labour. Audio frequency analysis of these signals yielded fetal blood velocity waveforms. Analysis of these waveforms demonstrated that placental vascular resistance to feto-placental blood flow is not altered by uterine contractions, artificial rupture of the membranes, the infusion of oxytocin nor the administration of analgesia during uncomplicated labour.

The effect of lumbar epidural analgesia on the rate of cervical dilatation and the outcome of labour of spontaneous onset.

A study of 1055 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.

Fetal blood velocity waveforms in normal pregnancy.

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.

Sex hormone levels and gonadotrophin release in premature ovarian failure.

Premature ovarian failure was studied in ten women under the age of 30; eight had an ovarian biopsy and five of these showed primordial follicles. Plasma levels of oestradiol and progesterone were similar to the follicular phase of a normal menstrual cycle, but in eight patients cervical smears showed a cornification index of less than one per cent. Levels of both androgens and of sex hormone binding globulin capacity were generally normal. Administration of LH-RH caused a release of FSH which was similar to post menopausal women and higher than both. Two patients were treated with exogenous gonadotrophins without effect.

Modification by sex steroids of LHRH response in the polycystic ovary syndrome.

Exogenously administered oestradiol or progesterone was found to induce augmentation of LH and FSH release in response to LHRH administration in patients with the polycystic ovary (PCO) syndrome. The effect of oestradiol upon LH release in the patients was significantly less than the augmented release induced in normal women (P less than 0-02). In contrast, progesterone induced a significantly greater LH release in PCO patients than normal women studied during the early follicular phase (P less than 0-001) but less than that in normal women studied during the mid-follicular phase of the cycle (P less than 0-01). The effects on FSH release in the PCO patients were less marked but similar to those in normal women with comparable basal steroid levels. The results suggest that both oestradiol and progesterone can modify the hypothalamic-pituitary axis in the PCO syndrome in a manner similar to that observed in normal women and a failure of these 'positive feedback' mechanisms does not appear to be the cause of the ovulatory deficiency in this syndrome.

Polycystic ovarian disease.

Sex hormone binding globulin (SHBG) capacity was reduced in 9 of 31 patients with polycystic ovarian (PCO) disease and the mean level in PCO patients was significantly less (p less than 0.001) than normal. Serum testosterone levels were elevated in 21 of 32 PCO patients and the mean level was significantly elevated (p less than 0.001). Serum androstenedione values were raised in 17 of 31 patients and the mean value was also significantly raised (p less than 0.001). Serum dehydroepiandrosterone sulphate (DHAS) concentrations were elevated in only 2 of 14 patients. Urinary 17-oxo and 17-oxogenic steroids were normal in all patients studied. Basal follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were normal but LH release following injection of luteinizing hormone-releasing hormone (LH-RH) was enhanced. A highly significant negative correlation (r=--0.449; p less than 0.01) was found between the logarithm of testosterone and the logarithm of LH levels. Serum prolactin concentrations were elevated in 4 of 21 PCO patients. Thyroid-stimulating hormone (TSH) values were normal. Eighteen of 20 patients ovulated following treatment with clomiphene and nine became pregnant. Five of 12 of patients treated with oestrogen/progesterone preparations noticed an improvement in their hirsutism. It is suggested that the normal cyclical release of LH is inhibited in PCO disease by a negative feedback by androgens to the hypothalamus or the pituitary, and that wedge resection should be reserved for patients in whom other forms of treatment have failed.

Hypothalmic-pituitary relationships in the polycystic ovary syndrome serum gonadotrophin levels following injection of oestradiol benzoate.

Injection of oestradiol benzoate was found to elicit a surge of luteinizing hormone (LH) in 15 of 19 patients with polycystic ovary (PCO) syndrome; follicle stimulating hormone (FSH) was also released, in conjunction with the LH surge, in eight patients. It is concluded that the oestrogen feedback mechanisms controlling mid-cycle gonadotrophin release are functioning normally in the majority of patients with PCO syndrome. Ovulation was subsequently induced by clomiphene alone in those patients who had an LH surge, and by a combination of clomiphene and human chorionic gonadotrophin (HCG) in those who had not shown any LH release.

A radioimmunoassay for the estimation of serum dehydroepiandrosterone sulphate in normal and pathological sera.

A radioimmunoassay is described for the measurement of dehydroepiandrosterone sulphate in serum. The method requires 0.1 ml of serum that needs no purification other than a single ether extraction. It is both rapid and economical, procedural losses are small and precision and accuracy are acceptable for both normal and pathological sera. Normal values have been established for children and adults which show a relationship to chronological age, values rising steadily as puberty intevenes, peak values occurring between 20 and 27 years, with a decline thereafter. An empirical curve was fitted to the data and approximate normal limits were obtained. The mean value for pregnanat women in the age range 20-40 years, was statistically significantly lower than in non-pregnant, premenopausal women. The levels of dehydroepiandrosterone sulphate in cord and newborn blood, were higher than at any other time during childhood until signs of puberty were demonstrable. Elevated levels are reported in six patients with untreated congenital adrenal hyperplasia and in one patient with a tumour of the adrenal cortex. It is suggested that this assay provides a useful and precise index of adrenal androgen secretion.

Characteristics of normal labour in different racial groups.

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 less than 0-001) and their infants significantly lighter than those of white (p less than 0-001) and of black (p less than 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.

Sex hormone levels and gonadotrophin release in the polycystic ovary syndrome.

The response to synthetic luteinizing hormone-releasing hormone was studied in eighteen patients with the polycystic ovary syndrome. The release of follicle-stimulating hormone was similar to that found in normal women. The mean response of luteinizing hormone was similar to that found in the luteal phase, but significantly greater (P less than 0-02) than that found in the early follicular phase of the normal menstrual cycle. Basal serum levels of FSH and LH, estimated in twenty-five patients, were similar to those found in normal subjects. The sex hormone binding globulin capacity was reduced in twenty-four of them. Basal serum testosterone levels were elevated in twelve of twenty-two patients and the mean level was significantly greater (P less than 0-01) than the mean level of normal women. Basal serum androstenecione levels were elevated in nine of twenty-two patients and the mean level was also significantly greater (P leess than 0-001) between basal testosterone and LH levels. These data suggest the pituitary gland of patients with the polycystic ovary syndrome contains adequate amounts of LH but that the ovulatory surge of LH which occurs in normal women is inhibited by testosterone acting on either the pituitary or, more probably, on the hypothalamus.