Intrauterine pressures in labours induced by amniotomy and oxytocin or vaginal prostaglandin gel compared with spontaneous labour

Uterine activity during the first stage of labour was measured by an intrauterine transducer in 22 women induced with intravaginal PGE2 gel, in 37 induced by amniotomy and intravenous oxytocin, and in nine women in spontaneous labour. The nulliparous women in the PGE2 gel group had a significantly longer pre-established phase of labour and a significantly shorter established phase than nulliparae induced by amniotomy and oxytocin. The mean levels of total uterine activity (kPas) during labour and the uterine activity integrals (kPas/15 min) were significantly lower in nulliparae induced with PGE2 gel than in those induced by amniotomy and oxytocin. These findings suggest that PGE2 gel has a positive, beneficial effect on cervical compliance during the pre-established phase, resulting in less myometrial effort during established labour. These effects were less evident in parous women, probably because of an innate lower cervical resistance due to their previous labours. Uterine activity patterns during the 4 h leading to full cervical dilatation in nulliparae were similar in labours induced with PGE2 gel and spontaneous labours, whereas labours induced by amniotomy and oxytocin exhibited a significantly different pattern. Expulsion of the fetus during normal labour is a function of both uterine contractions and a decrease in the cervical resistance and the data suggest that induction by PGE2 gel more closely mimics spontaneous labour, whereas the predominant effect of oxytocin is to stimulate myometrial activity.     

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.     

The influence of spontaneous and induced labour on the rise in prostaglandins at amniotomy

Summary. Maternal peripheral plasma levels of 13, 14-dihydro-15-keto-prostaglandin F (PGFM) were measured immediately before and 5 min after amniotomy. Three groups of women were studied: women in late pregnancy; women in spontaneous labour; and women who had received intravaginal prostaglandin E₂ (PGE₂) pessary. There was no significant difference in the magnitude of the rise in PGFM after amniotomy in late pregnancy or during spontaneous labour suggesting that labour has no influence on the release of prostaglandin F_2α (PGF_2α) induced by artificial rupture of the fetal membranes. However, local administration of PGE₂ before amniotomy caused a greater rise in PGFM suggesting that PGE₂ can influence the release and/or metabolism of PGF_2α.     

Mid-second-trimester labor induction: concentrated oxytocin compared with prostaglandin E2 vaginal suppositories

A concentrated oxytocin infusion and prostaglandin E2 (PGE2) vaginal suppositories were compared in a retrospective analysis for indicated abortion in the mid-second trimester (17-24 weeks' gestation). Eighty-one women underwent second-trimester pregnancy termination, 59 by PGE2 suppositories and 22 by concentrated oxytocin infusion. Success was achieved by PGE2 in 93% (55 of 59) and oxytocin in 91% (20 of 22). The mean duration of labor was 13.1 hours with PGE2 and 8.2 hours with oxytocin. The mean dose of PGE2 was 65.2 mg; of oxytocin, 200 units. Women who received PGE2 experienced nausea (46%), vomiting (37%), fever (64%), and diarrhea (20%) despite appropriate premedication. Few side effects occurred in the women who were treated with oxytocin. We conclude that concentrated oxytocin infusion seems to be a reasonable alternative to PGE2 vaginal suppositories for induction of labor in the mid-second trimester.     

The induction of labour with prostaglandin F2alpha by intravenous infusion. II. A comparison of fetal and maternal acid-base values with those found in oxytocin induced labour and in spontaneous labour

Serial determination of fetal and maternal pH, Pco2 and BDECF was performed in 34 cases of labour inductions with intravenously administered prostaglandin F2alpha or oxytocin. These values were compared with those found in ten cases of spontaneous labour. With the exception of eight cases of "high risk pregnancies" all the remaining parturients were healthy and within the 38th to 42nd week of gestation. With regard to the cases of "uncomplicated" pregnancies the general patterns of the acid-base changes were very similar in the three groups. The BDECF values in fetal scalp blood, however, showed a more marked tendency to increase in the group induced with prostaglandin. Further analysis of this group revealed that the rise of BDECF values could be attributed to cases with episodes of uterine hypertonus or signs of uterine incoordination. In the "high risk" pregnancy group the pH values in fetal scalp blood were lower and the BDECF values higher than in the group of "normal" pregnancy cases. The general pattern and the magnitude of the acid-base changes do not seem to be influenced by the administration of oxytocin or prostaglandin F2alpha as induction agents providing uterine activity is normal. Abnormal uterine activity, initiated by any of the two induction agents, is, however, associated with an increased risk of fetal acidosis.     

Induction of labour with prostaglandin E2 vaginal gel in women with one previous caesarean section

ObjectiveTo study the outcome of induction of labour with prostaglandin E2 (PGE2) vaginal gel in those with one previous caesarean section.DesignOne year prospective comparative study.SettingA tertiary care Armed Forces Hospital, Muscat.PopulationForty-six women with one previous caesarean section (CS) underwent PGE2 vaginal gel induction (study group). Hundred women with previous CS had gone into spontaneous onset of labour (control group).Main outcome measuresPrimary outcome measures are mode of delivery and uterine rupture. Others are neonatal outcome, indications for caesarean section, and complications like, postpartum haemorrhage and infectious morbidity.ResultsOverall rate of vaginal delivery after caesarean section (VBAC) was 65.21% and 79% in the study and control groups, respectively. There were 7 cases of neonatal intensive care unit (NICU) admissions (7%) in the control group; however, none in the study group. Caesarean section done for foetal distress was 5/16 CS in the study group (31.25%) and 10/21 CS in the control group (47.61%). There were no cases of uterine rupture in both control and study groups.ConclusionInduction of labour with prostaglandin E2 vaginal gel in women with one previous caesarean section does not significantly increase the risk of caesarean section rate or ruptured uterus and does not adversely affect immediate neonatal outcome.     

Uterine action after induction of labour with oral prostaglandin E2 tablets compared with intravenous oxytocin.

Uterine action throughout the whole of labour induced by low amniotomy and either oral prostaglandin E2 tablets or intravenous ocytocin was studied in 10 randomly matched pairs of patients. Oral prostaglandin E2 tablets induced fewer contractions per hour, and these contractions were longer and more variable in length than those induced by intravenous oxytocin. There was no difference in basal uterine tone or in the amplitude of contractions. A comparison was made between the outcome of labour induced by low amniotomy and either oral prostaglandin E2 tablets 0-5 mg. hourly in 65 patients, or intravenous ocytocin in 41 patients. This dose of prostaglandin E2 tablets was an inadequate adjunct to low amniotomy in nulliparous patients. Despite this, the induction-delivery interval for the whole prostaglandin group was not significantly greater than that for the oxytocin group. There were no significant differences in fetal heart rate pattern, or in the incidence of gastro-intestinal side-effects between the two groups.     

Effects of early augmentation of labour with amniotomy and oxytocin in nulliparous women: a meta-analysis

Objectives To estimate the effects among nulliparae of early augmentation with amniotomy and oxytocin on caesarean delivery, and on other indicators of maternal and neonatal morbidity including transfusion, Apgar score < 7 at 5 minutes, and admission to the special care nursery.
Design Meta-analysis.
Methods Published studies were identified through manual and computerised searches. Two unpublished studies were identified through direct communication with the investigators. Twelve trials were identified which compared a policy of early labour augmentation including amniotomy followed by oxytocin with a less active form of management. Two methodologically unacceptable studies were excluded. Studies were grouped according to whether they admitted only women with abnormal progress (therapy trials: n = 3) or accepted women with normal labour (prevention trials: n = 7).
Results Unstratified analysis did not provide support for the hypothesis that early augmentation reduces the risk of caesarean section (typical odds ratio [OR] 0.9; 95% CI 0.7–1.1). The typical odds ratio for prevention trials was similar to that obtained in the unstratified analysis (typical OR 0.9, 95% CI 0.7–1.2). Although only a small number of women have been randomised in therapy trials, a trend toward a reduction in the rate of caesarean section with early intervention was seen in this group (typical OR 0.6,95% CI 0.2–1.4).
Conclusions Early augmentation does not appear to provide benefit over a more conservative form of management in the context of care of nulliparous women with mild delays in the progress of labour. In the context of established delay in labour, an active policy of augmentation may reduce the risk of caesarean section. However, only three small trials have been performed in this context, and they do not have adequate power to allow firm conclusions to be drawn.     

Intrauterine pressure studies in multigravid patients in spontaneous labour: effect of oxytocin augmentation in delayed first stage

Summary. Uterine activity was assessed by measuring the uterine activity integral (UAI) in 116 black multigravid patients in spontaneous active labour at term. Although individual patients showed a wide range of mean UAI levels, normal labour (group I, n = 54) was associated with a mean UAI level of 1640 kPas/15 min which was higher than the mean level observed in patients in whom delay in cervical dilatation occurred in active labour. The patients who failed to progress in labour were treated with oxytocin infusion and 32 of them made good progress in labour and achieved vaginal delivery (group IIa: mean UAI pre-oxytocin treatment 1040 (SD424) kPas/15min, post-oxytocin 1890 (SD 559) kPas/15min). The other 23 patients required operative delivery (group IIb) despite correction of uterine activity after oxytocin treatment (pre-oxytocin mean UAI 1230 (SD570) kPas/15min, post-oxytocin 1815 (SD650) kPas/15min). The rate of oxytocin infusion varied between patients from 2 to 16 mU/min but in 75% uterine activity was corrected to normal levels by a dose of ≤8 mU/min. It is concluded that delay in progress in labour is associated with lower intrauterine pressures than are present in normal labour, and that management of patients presenting with inefficient uterine action may benefit from the use of uterine activity integral measurements.     

Intrauterine pressure studies in multigravid patients in spontaneous labour: effect of oxytocin augmentation in delayed first stage

Uterine activity was assessed by measuring the uterine activity integral (UAI) in 116 black multigravid patients in spontaneous active labour at term. Although individual patients showed a wide range of mean UAI levels, normal labour (group I, n = 54) was associated with a mean UAI level of 1640 kPas/15 min which was higher than the mean level observed in patients in whom delay in cervical dilatation occurred in active labour. The patients who failed to progress in labour were treated with oxytocin infusion and 32 of them made good progress in labour and achieved vaginal delivery (group IIa: mean UAI pre-oxytocin treatment 1040 (SD 424) kPas/15 min, post-oxytocin 1890 (SD 559) kPas/15 min). The other 23 patients required operative delivery (group IIb) despite correction of uterine activity after oxytocin treatment (pre-oxytocin mean UAI 1230 (SD 570) kPas/15 min, post-oxytocin 1815 (SD 650) kPas/15 min). The rate of oxytocin infusion varied between patients from 2 to 16 mU/min but in 75% uterine activity was corrected to normal levels by a dose of less than or equal to 8 mU/min. It is concluded that delay in progress in labour is associated with lower intrauterine pressures than are present in normal labour, and that management of patients presenting with inefficient uterine action may benefit from the use of uterine activity integral measurements.     

Prolactin and cortisol levels during spontaneous and oxytocin induced labour and the effect of meperidine

The effect of stress during labour on the plasma concentration of prolactin and cortisol was studied in 30 healthy multiparous women. The plasma concentrations of prolactin and cortisol were measured by radioimmunoassay during oxytocin induced labour, spontaneous labour, delivery and postpartum 24 h. The parturients were divided into three groups. The first group was given oxytocin for the induction of labour, the second group was also given oxytocin for the induction of labour and 100 mg of meperidine was administered intramuscularly for relief of pain and anxiety, and the third group was the control group with normal parturients who did not receive any medication. The prolactin levels showed a fall during labour in all the groups, but this fall was more marked in the first group where stress was evident. The concentrations of cortisol tended to increase during labour and reached a maximum at delivery in all three groups but in the meperidine group this level was significantly lower than the first and control groups. These results give further support to the hypothesis that maternal stress leads to a reduced concentration of prolactin and increased concentration of cortisol whereas relief of pain and maternal anxiety with meperidine lessens both effects.     

Induction of labor by prostaglandin E2: intracervical gel or vaginal pessaries?

To investigate the best route of prostaglandin medication for induction of labor, 125 pregnant women with unfavorable cervices (Bishop scores less than or equal to 6) were randomized to induction of labor with either PGE2 (0.5 mg) in a viscous intracervical gel once daily or PGE2 pessaries (2.5 mg) 1-2 a day. As estimated by life table analysis, the pessaries were significantly more effective inducing vaginal delivery compared to intracervical gel (24 h: P less than 0.025, 48 h: P less than 0.01, logrank test) and vaginal delivery was obtained within 24 h/48 h in 50%/72% of the women in the pessary group and in 29%/55% of the women in the intracervical group. Cervical ripening was found within 3 h (P less than 0.001) and in the subsequent 3 to 24 h period (P less than 0.005) after both treatments, no difference being found between the groups. The pessaries were much more effective inducing regular contractions compared to the intracervical gel (P less than 0.005, logrank test), so the latter seems preferable if cervical ripening rather than induction is intended. No difference was found analyzing the active labor period. No difference was found in methods of delivery, neonatal parameters (Apgar scores, umbilical artery blood pH and standard base excess), and the patients' attitude towards both methods of induction were equally favorable.     

Planimetric analysis of labour induced by means of prostaglandin F 2 alpha and oxytocin (author's transl)]

Planimetry has been used to analyse the tocographic tracings recorded from 29 deliveries induced by means of prostaglandin F 2 alpha as well as those recorded from 28 deliveries induced by means of oxytocin. The contraction-causing effect of prostaglandin was found to be milder than that of oxytocin. Prostaglandin F 2 alpha, consequently, proved to be superior to oxytocin in handling placental insufficiency.     

Controlled study comparing vaginal prostaglandin E2 pessaries with intravenous oxytocin for the stimulation of labour after spontaneous rupture of the membranes

Summary. In a prospective randomized study, 36 patients with spontaneous rupture of the membranes of ≥4 h duration were stimulated with 3 mg vaginal prostaglandin E₂ pessaries or intravenous oxytocin. Oxytocin stimulation was associated with shorter labours and a lower incidence of abnormal cervimetric progress. Of the patients given prostaglandin pessaries, 40% required a second dose after 4 h for slow progress; 45% of the primigravidae subsequently developed abnormal labour which was corrected by augmentation with oxytocin in all cases. One caesarean section was carried out for disproportion, and the remaining 35 patients were delivered vaginally. Prostaglandin pessaries were not associated with an increased incidence of hyperstimulation or sepsis. In conclusion, although PGE₂ pessaries are safe in spontaneous rupture of the membranes, intravenous oxytocin is more efficient in stimulating labour.     

A randomised controlled trial of early versus delayed use of amniotomy and oxytocin infusion in nulliparous labour

Objective To compare routine amniotomy and early intravenous oxytocin (active management of labour) with a more selective use of amniotomy and oxytocin in women in true labour who received comparable continuous supportive midwifery care.
Design Randomised controlled trial of nulliparous clinic patients in spontaneous labour at term. Setting Labour and delivery ward of a university teaching hospital.
Participants Three hundred and six parturients: 152 received active management of labour; 154 were more selectively managed.
Interventions 1. Active management: early amniotomy, early use of oxytocin. 2. Selective intervention management: no routine amniotomy and more selective use of oxytocin.
Outcome measures Use of oxytocin and amniotomy. Labour duration, mode of delivery.
Results Maternal characteristics were comparable in both groups. Amniotomy was more often performed (91% versus 57%,   P < 0.01  ) and oxytocin more often used (53% versus 27%, P < 001) in the active management group. The first stage of labour, however, was only shortened by half an hour in the active management group (254 min versus 283 min,   P = 0.087  ). Caesarean section rate (3.9% versus 2.6%), spontaneous vaginal delivery rate (78% versus 79%) and neonatal outcome were not significantly different between groups.
Conclusion Within a set-up of strict labour diagnosis and supportive midwifery care, routine amniotomy and early use of oxytocin offered no advantage over a more selective use of amniotomy and oxytocin in terms of mode of delivery and labour duration.     

Comparison of intravenous oxytocin and vaginal prostaglandin E2 gel in women with unripe cervixes and premature rupture of the membranes

To induce cervical priming and labor, 20 nulliparous term pregnant women with premature rupture of the membranes and unfavorable cervical states were randomly given either oxytocin intravenously or 4 mg prostaglandin E2 in gel intravaginally. One of ten women receiving oxytocin had a favorable cervical state within five hours and vaginal delivery within 24 hours after the start of the infusion compared with six of ten women after prostaglandin E2 gel application. This difference is statistically significant (P less than .01). The number of instrumental deliveries was nine (four cesarean sections and five vacuum extractions) in the oxytocin-treated patients compared with only two vacuum extractions in women who received prostaglandin E2 gel. This difference is also statistically significant (P less than .01, Fischer exact test). In a subsequent open study, 4 mg prostaglandin E2 gel was applied vaginally to 17 term pregnant women of mixed parity with premature rupture of the membranes and unfavorable cervixes. In 12 women a favorable cervical state was achieved within five hours after gel application, and all these women were delivered within 24 hours. None of the women required cesarean section but two required delivery by vacuum extraction. There were no perinatal losses, but two infants in the oxytocin-treated group had Apgar scores less than 7 at five minutes. At pediatric follow-up after two and six months, all infants were normal. In both obstetric and perinatal outcome prostaglandin E2 gel thus seems to be superior to oxytocin for labor induction in term pregnant patients with premature rupture of the membranes and unfavorable cervixes.