Continued versus discontinued oxytocin stimulation in the active phase of labour (CONDISOX): double blind randomised controlled trial

How labor induction methods have evolved throughout history, from the Egyptian era to the present day: evolution, effectiveness, and safety

Induction of labor (IOL) is currently used for one in 10 pregnancies globally. Methods used for induction have shown major changes over time. Medical interventions trace their origins back to ancient civilizations, with evidence suggesting that they began over 5000 years ago in ancient Egypt. During this era, the Egyptians employed natural remedies such as castor oil and date fruits for the IOL. These early practices highlight the rich history and long-standing tradition of using natural substances in medical treatments, laying the foundation for the development of modern obstetric practices. After that, Hippocrates practiced mammary stimulation and mechanical cervical dilatation about 2500 years ago in Greece. Since then, there has been a marked change, especially over the last century, with the development of safer and more effective methods. Mechanical methods were the main method until the early 20th century, which were then substituted by pharmacological methods with more experiments in the mid to late 20th century. Nowadays, effectiveness, safety, cost, and client satisfaction are the main determinants of the methods used. This review summarizes how labor induction practices have evolved from the Egyptian era to the present-day randomized controlled trials and meta-analysis evidence, paying attention to their effectiveness, safety, and future directions.

Continuation versus discontinuation of intravenous oxytocin in the active phase of labour

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effects of discontinuing intravenous oxytocin stimulation in pregnant women during the active phase of induced or augmented labour.

High-Dose versus Low-Dose Oxytocin for Labor Augmentation: A Meta-Analysis of Randomized Controlled Trials

Background/Objectives: Although oxytocin administration is recommended for delayed labor progress, there is no consensus over the preferred optimal dose of oxytocin. We aimed to perform a meta-analysis of pregnancy outcomes comparing high-dose versus low-dose oxytocin regimens for augmentation of delayed labor. Methods: PubMed, Embase, and Cochrane databases were systematically searched for studies comparing high-dose with low-dose oxytocin for labor augmentation from inception up to May 2023. The outcomes assessed were cesarean rate, instrumental delivery rate, postpartum hemorrhage, neonatal death, and uterine tachysystole. Subgroup analysis was performed with randomized controlled trials (RCTs) and propensity-matched studies. Statistical analysis was performed using Rstudio. Heterogeneity was assessed with I2 statistics, and a random-risk effect was used if I2 > 50%. Results: Twenty-one studies met inclusion criteria, and eighteen were RCTs. A total of 14.834 patients were included, of whom 7.921 (53.3%) received high-dose and 6.913 (46.6%) received low-dose oxytocin during labor augmentation. No statistical differences were found in cesarean delivery, neonatal mortality, postpartum hemorrhage and vaginal instrumentation rate. However, uterine tachysystole incidence was significantly higher with high-dose oxytocin (95% Cl, 1.30-1.94, p = 0.3; 0.6; I2 = 9%). Conclusions: Labor augmentation with a low-dose oxytocin regimen is effective as with a high-dose regimen, but with significantly less uterine tachysystole events, which can lead to intrauterine and neonatal complications. Our findings suggest that a low-dose regimen may be safe and effective for labor augmentation in medical practice.

Continued versus discontinued oxytocin stimulation in the active phase of labour (CONDISOX): individual management based on artificial intelligence - a secondary analysis

BACKGROUND

Current guidelines regarding oxytocin stimulation are not tailored to individuals as they are based on randomised controlled trials. The objective of the study was to develop an artificial intelligence (AI) model for individual prediction of the risk of caesarean delivery (CD) in women with a cervical dilatation of 6 cm after oxytocin stimulation for induced labour. The model included not only variables known when labour induction was initiated but also variables describing the course of the labour induction.

METHODS

Secondary analysis of data from the CONDISOX randomised controlled trial of discontinued vs. continued oxytocin infusion in the active phase of induced labour. Extreme gradient boosting (XGBoost) software was used to build the prediction model. To explain the impact of the predictors, we calculated Shapley additive explanation (SHAP) values and present a summary SHAP plot. A force plot was used to explain specifics about an individual's predictors that result in a change of the individual's risk output value from the population-based risk.

RESULTS

Among 1060 included women, 160 (15.1%) were delivered by CD. The XGBoost model found women who delivered vaginally were more likely to be parous, taller, to have a lower estimated birth weight, and to be stimulated with a lower amount of oxytocin. In 108 women (10% of 1060) the model favoured either continuation or discontinuation of oxytocin. For the remaining 90% of the women, the model found that continuation or discontinuation of oxytocin stimulation affected the risk difference of CD by less than 5% points.

CONCLUSION

In women undergoing labour induction, this AI model based on a secondary analysis of data from the CONDISOX trial may help predict the risk of CD and assist the mother and clinician in individual tailored management of oxytocin stimulation after reaching 6 cm of cervical dilation.

Routine vaginal examination to assess labor progress at 8 compared to 4 hours after early amniotomy following Foley balloon ripening in the labor induction of multiparas: a randomized trial

BACKGROUND

Vaginal examination to monitor labor progress is recommended at least every 4 hours, but it can cause pain and embarrassment to women. Trial data are limited on the best intensity for vaginal examination. Vaginal examination is not needed for oxytocin dose titration after an amniotomy has been performed and oxytocin infusion started. The Foley balloon commonly ripens the cervix without strong contractions. Amniotomy and oxytocin infusion are usually required to drive labor.

OBJECTIVE

This study aimed to evaluate the first vaginal examination at 8 vs 4 hours after amniotomy-oxytocin after Foley ripening in multiparous labor induction.

STUDY DESIGN

A randomized controlled trial was conducted from October 2021 to September 2022 at the University Malaya Medical Center, Kuala Lumpur, Malaysia. Multiparas at term were recruited at admission for labor induction. Participants were randomized to a first routine vaginal examination at 8 or 4 hours after Foley balloon ripening and amniotomy. Titrated oxytocin infusion was routinely commenced after amniotomy to initiate contractions. The 2 primary outcomes were the time from amniotomy to delivery (noninferiority hypothesis) and maternal satisfaction (superiority hypothesis). Data were analyzed using the Student t test, Mann-Whitney U test, and chi-square test (or Fisher exact test), as suitable for the data.

RESULTS

A total of 204 women were randomized, 102 to each arm. Amniotomy to birth intervals were 4.97±2.47 hours in the 8-hour arm and 5.79±3.17 hours in the 4-hour arm (mean difference, -0.82; 97.5% confidence interval, -1.72 to 0.08; P=.041; Bonferroni correction), which were noninferior within the prespecified 2-hour upper margin, and the maternal satisfaction scores (11-point 0-10 numerical rating scale) with allocated labor care were 9 (interquartile range, 8-9) in the 8-hour arm and 8 (interquartile range, 7-9) in the 4-hour arm (P=.814). In addition, oxytocin infusion to birth interval difference was noninferior within the 97.5% confidence interval (-1.59 to 0.23) margin of 1.3 hours. Of the maternal outcomes, the amniotomy to first vaginal examination intervals were 3.9±1.8 hours in the 8-hour arm and 3.4±1.3 hours in the 4-hour arm (P=.026), and the numbers of vaginal examinations were 2.00 (interquartile range, 2.00-3.00) in the 8-hour arm and 3.00 (interquratile range, 2.00-3.25) in the 4-hour arm (P<.001). For the 8-hour arm, the first vaginal examination was less likely to be as scheduled and more likely to be indicated by sensation to bear down (P<.001), and the epidural analgesia rates were lower (13/102 participants [12.7%] in the 8-hour arm vs 28/102 participants [27.5%] in the 4-hour arm; relative risk, 0.46; 95% confidence interval, 0.26-0.84; P=.009). Other outcomes of the mode of delivery, indications for cesarean delivery, and delivery blood loss were not different. Neonatal outcomes were not different.

CONCLUSION

Routine first vaginal examination at 8 hours compared with that at 4 hours was noninferior for the time to birth but did not improve maternal satisfaction.

Oxytocin: physiology, pharmacology, and clinical application for labor management

Oxytocin is a peptide hormone that plays a key role in regulating the female reproductive system, including during labor and lactation. It is produced primarily in the hypothalamus and secreted by the posterior pituitary gland. Oxytocin can also be administered as a medication to initiate or augment uterine contractions. To study the effectiveness and safety of oxytocin, previous studies have randomized patients to low- and high-dose oxytocin infusion protocols either alone or as part of an active management of labor strategy along with other interventions. These randomized trials demonstrated that active management of labor and high-dose oxytocin regimens can shorten the length of labor and reduce the incidence of clinical chorioamnionitis. The safety of high-dose oxytocin regimens is also supported by no associated differences in fetal heart rate abnormalities, postpartum hemorrhage, low Apgar scores, neonatal intensive care unit admissions, and umbilical artery acidemia. Most studies reported no differences in the cesarean delivery rates with active management of labor or high-dose oxytocin regimens, thereby further validating its safety. Oxytocin does not have a predictable dose response, thus the pharmacologic effects and the amplitude and frequency of uterine contractions are used as physiological parameters for oxytocin infusion titration to achieve adequate contractions at appropriate intervals. Used in error, oxytocin can cause patient harm, highlighting the importance of precise administration using infusion pumps, institutional safety checklists, and trained nursing staff to closely monitor uterine activity and fetal heart rate changes. In this review, we summarize the physiology, pharmacology, infusion regimens, and associated risks of oxytocin.

Impact of discontinuing oxytocin in active labour on neonatal morbidity: an open-label, multicentre, randomised trial

BACKGROUND

Oxytocin is effective in reducing labour duration but can be associated with fetal and maternal complications that could potentially be reduced by discontinuing the treatment during labour. We aimed to assess the impact of discontinuing oxytocin during active labour on neonatal morbidity.

METHODS

STOPOXY was a multicentre, randomised, open-label, controlled, superiority trial conducted in 21 maternity units in France. Participants who received oxytocin before 4 cm dilation were randomly assigned 1:1 to either discontinuous oxytocin (oxytocin infusion stopped beyond a cervical dilation equal to or greater than 6 cm) or continuous oxytocin (administration of oxytocin continued until delivery). Randomisation was stratified by centre and parity. The primary outcome, neonatal morbidity, was assessed at birth using a composite variable defined by an umbilical arterial pH at birth less than 7·10, a base excess greater than 10 mmol/L, umbilical arterial lactates greater than 7 mmol/L, a 5-min Apgar score less than 7, or admission to the neonatal intensive care unit. Efficacy and safety was assessed in participants who were randomly assigned (excluding those who withdrew consent or were deemed ineligible after randomisation) and had reached a cervical dilation of at least 6 cm. This trial is registered with ClinicalTrials.gov, NCT03991091.

FINDINGS

Of 2459 participants randomly assigned between Jan 13, 2020, and Jan 24, 2022, 2170 were eligible to receive the intervention and were included in the final modified intention-to-treat analysis. The primary outcome occurred for 102 (9·6%) of 1067 participants (95% CI 7·9 to 11·5) in the discontinuous oxytocin group and for 101 (9·2%) of 1103 participants (7·6 to 11·0) in the continuous oxytocin group; absolute difference 0·4% (95% CI -2·1 to 2·9); relative risk 1·0 (95% CI 0·8 to 1·4). There were no clinically significant differences in adverse events between the two groups of the safety population.

INTERPRETATION

Among participants receiving oxytocin in early labour, discontinuing oxytocin when the active phase is reached does not clinically or statistically significantly reduce neonatal morbidity compared with continuous oxytocin.

FUNDING

French Ministry of Health and the Département de la Recherche Clinique et du Développement de l'Assistance Publique-Hôpitaux de Paris.

Continuous vs intermittent induction of labor with oxytocin in nulliparous patients: a randomized controlled trial

BACKGROUND

Oxytocin is considered the drug of choice for the induction of labor, although the optimal protocol and infusion duration remain to be determined.

OBJECTIVE

This study aimed to assess whether the duration of oxytocin infusion increases 24-hour delivery rates and affects the length of time-to-delivery and patient's experience.

STUDY DESIGN

A randomized controlled trial was performed at a single tertiary medical center, between January 1, 2020 and June 30, 2022. Nulliparous patients with a singleton pregnancy at a vertex presentation and a Bishop score ≥6 were randomly assigned to receive either continuous (16 hours, with a 4 hours pause in between infusions) or intermittent (8 hours, with a 4 hours pause in between infusions) oxytocin infusion, until delivery. In both groups, infusion was halted when signs of maternal or fetal compromise were observed. Randomization was conducted with a computer randomization sequence generation program. The primary outcome was delivery within 24 hours from the first oxytocin infusion and the secondary outcome included time-to-delivery, mode of delivery, and additional maternal and neonatal outcomes. Seventy-two patients per group were randomized to reach 80% statistical power with a 20% difference in the primary outcome according to previous studies.

RESULTS

A total of 153 patients were randomized, 72 to the continuous oxytocin infusion group and 81 to the intermittent infusion group. The total oxytocin infusion time was similar between the groups. Patients in the continuous arm were more likely to deliver within 24 hours from oxytocin initiation (79.73% vs 62.96%, P<.05), and had a shorter oxytocin-to-delivery time interval, compared with patients receiving intermittent treatment (9.3±3.7 hours vs 21±11.7 hours, P<.001). Furthermore, time from ruptured membranes to delivery was shorter (9.3±3.7 hours vs 21±11.7 hours; P<.0001) and chorioamnionitis was less frequent (9.46% vs 21%; P<.05) in the continuous compared with the intermittent arm. Cesarean delivery rate was 20% in both groups (P=.226). There was no difference in postpartum hemorrhage, or adverse neonatal outcomes between the groups. Patients receiving continuous oxytocin infusion were more satisfied with the birthing experience.

CONCLUSION

Continuous infusion of oxytocin for labor induction in nulliparous patients with a favorable cervix may be superior to intermittent oxytocin infusion, because it shortens time-to-delivery, decreases chorioamnionitis rate, and improves maternal satisfaction, without affecting adverse maternal or neonatal outcomes.

Continued versus discontinued oxytocin stimulation in the active phase of induced labour: Factors associated with unexpectedly high rates of conversion to open label oxytocin in the CONDISOX trial

OBJECTIVE

To examine the factors associated with unexpectedly high rates of conversion to open label oxytocin in the CONDISOX trial of continuation versus discontinuation of oxytocin infusion during induced labour.

DESIGN

Secondary retrospective analysis of data from a prospective randomised controlled trial.

SETTING

Nine hospitals in Denmark and one in the Netherlands between 8 April 2016 and 30 June 2020.

POPULATION OR SAMPLE

1200 women having labour induced.

METHODS

Analysis of outcomes by actual management.

MAIN OUTCOME MEASURES

Mode of delivery and associated variables.

RESULTS

Switching to open label oxytocin (42.4% overall) was associated with nulliparity, an unripe cervix, larger babies and higher rates of delivery by caesarean section.

CONCLUSIONS

In the CONDISOX trial, slow labour was associated with features suggesting a higher 'resistance to progress', often prompting the use of open-label oxytocin infusion rather than study medication.

Peripartum effects of synthetic oxytocin: The good, the bad, and the unknown

The first clinical applications of oxytocin (OT) were in obstetrics as a hormone to start and speed up labor and to control postpartum hemorrhage. Discoveries in the 1960s and 1970s revealed that the effects of OT are not limited to its peripheral actions around birth and milk ejection. Indeed, OT also acts as a neuromodulator in the brain affecting fear memory, social attachment, and other forms of social behaviors. The peripheral and central effects of OT have been separately subject to extensive scrutiny. However, the effects of peripheral OT-particularly in the form of administration of synthetic OT (synOT) around birth-on the central nervous system are surprisingly understudied. Here, we provide a narrative review of the current evidence, suggest putative mechanisms of synOT action, and provide new directions and hypotheses for future studies to bridge the gaps between neuroscience, obstetrics, and psychiatry.

Use and Effects of Augmentation of Labor with Oxytocin: A Single-Center, Retrospective, Case-Control Study of 4350 Women in Warsaw, Poland, 2015-2020

BACKGROUND Although there have been some recent clinical trials on the effects of augmentation of labor with oxytocin, or augmentation of labor, there are no clinical guidelines to explain the variations in obstetric practice between countries and within countries. This retrospective case-control study from a single center in Warsaw, Poland aimed to evaluate the use and effects of augmentation of labor with oxytocin in 4350 women between 2015 and 2020. MATERIAL AND METHODS This was a single-center, retrospective, case-control study in which 29 455 cases were qualified for analysis. The study included the analysis of 2 groups: the study group consisted of 4382 patients who underwent stimulation of childbirth, and the control group consisted of 25 073 patients who did not undergo this obstetric procedure. RESULTS Multivariate logistic regression analysis showed that the factors increasing the frequency of augmentation of labor were higher BMI (P<0.05), preinduction (P<0.05), epidural anesthesia (P<0.05), and family present at birth (P<0.05). Factors influencing reduction in the frequency of augmentation of labor were higher number of deliveries (P<0.05), vaginal birth after cesarean (P<0.05), and pre-pregnancy hypertension (P<0.05). CONCLUSIONS This study from a single center in Poland showed that BMI, preinduction, epidural anesthesia, and family present at birth significantly increased the frequency of labor stimulation with oxytocin. However, a history of previous pregnancies, previous cesarean sections, and pre-pregnancy hypertension significantly reduced the frequency of augmentation of labor with oxytocin.

Continued versus discontinued oxytocin after the active phase of labor: An updated systematic review and meta-analysis

Objective

To systematically assess the effect of discontinued vs continued oxytocin after active stage of labour is established.

Methods

Pubmed, Embase, and the Cochrane Library were systematically searched to 18 April 2021. The risk ratio or mean difference with corresponding 95% confidence interval were computed to investigate the effect of intervention or control on maternal and fetus outcomes. This review was registered in the International Prospective Register of Systematic Reviews: CRD42021249635.

Results

Discontinuing oxytocin when the active labour was established might decrease the risk of cesarean delivery [RR (95% CI): 0.84 (0.72–0.98), P = 0.02]. However, when we restricted our analysis to women who performed cesarean section after the active phase was reached, the difference was no longer significant [RR (95% CI): 0.82 (0.60–1.10), P = 0.19]. The incidence of uterine tachysystole [RR (95% CI): 0.36 (0.27–0.49)], postpartum hemorrhage [RR (95% CI): 0.78 (0.65–0.93)], and non-reassuring fetal heart rate [RR (95% CI): 0.66 (0.58–0.76)] were significantly lower in the oxytocin discontinuation group. We also found a possible decrease in the risk of chorioamnionitis in discontinued oxytocin group [RR (95% CI): 2.77 (1.02–5.08)]. An increased duration of active [MD (95% CI): 2.28 (2.86–41.71)] and second [MD (95% CI): 5.36 (3.18–7.54)] phase of labour was observed in discontinued oxytocin group, while the total delivery time was not significantly different [MD (95% CI): 20.17 (-24.92–65.26)].

Conclusion

After the active labor is reached, discontinuation of oxytocin could be considered a new recommendation for the improved maternal and fetal outcomes without delaying labour.

Oxytocin administration for induction and augmentation of labour in polish maternity units - an observational study

BACKGROUND

There is not enough data regarding practices and protocols on the dose of oxytocin administrated to women during labour. Empirical evidence indicates that compliance with the guidelines improves the quality of healthcare and reduces adverse effects. The study aimed to evaluate practices of oxytocin provision for labour induction and augmentation in two maternity units in Poland.

METHODS

The article presents a prospective observational study. Data from 545 (n = 545) labours was collected in two maternity units. First, the total dose (the total amount of oxytocin provided from the beginning in the labour ward until delivery including the III and IV stage of labour) and cumulative dose of oxytocin (the amount of oxytocin given until the birth of the neonate) administered to women during labour was calculated. Then, the relationship between the cumulative dose of oxytocin and short term perinatal outcomes (mode of delivery, use of epidural anaesthesia, Apgar scores, birth weight and postpartum blood loss) was analysed. Finally, the compliance of oxytocin supply during labour with national guidelines in the following five criteria: medium, start dose, escalation rate, interval, the continuation of infusion after established labour was examined.

RESULTS

The average cumulative dose of oxytocin administrated to women before birth was 4402 mU following labour induction and 2366 mU following labour augmentation. The actual administration of oxytocin deviated both from the unit and national guidelines in 93.6% of all observed labours (mainly because of continuation of infusion after established labour). We found no statistically significant correlation between the cumulative dose of oxytocin administered and mode of delivery, immediate postpartum blood loss or Apgar scores. There was no observed effect of cumulative dose oxytocin on short-term perinatal outcomes. The two units participating in the study had similar protocols and did not differ significantly in terms of total oxytocin dose, rates of induction and augmentation - the only observed difference was the mode of delivery.

CONCLUSIONS

The study showed no effect of the mean cumulative oxytocin dose on short-term perinatal outcomes and high rate of non-compliance of the practice of oxytocin administration for labour induction and augmentation with the national recommendations. Cooperation between different professional groups of maternity care providers should be considered in building national guidelines for maternity care.. Further studies investigating possible long-term effects of the meant cumulative dose of oxytocin and the reasons for non-compliance of practice with guidelines should be carried out.