Tachysystole and risk of cesarean section after labor induction using misoprostol: a cohort study

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Uterine tachysystole frequently manifests after cervical ripening by misoprostol vaginal inserts. Currently, there is insufficient evidence regarding the clinical impact of tachysystole during induction of labor. Therefore, the objective of the current study is to examine if tachysystole is associated with an increased risk of cesarean section following induction of labor by misoprostol vaginal inserts. Methods We conducted a retrospective cohort study of 446 women over 37 weeks of gestation admitted for labor induction by misoprostol vaginal inserts between May 2016 and May 2017. Fetal heart rate and uterine activity tracings were assessed for tachysystole, defined as ≥ 6 contractions per 10 minutes, averaged over a 30-minute window. Univariate analysis was performed by using t-test and Chi-square, comparing demographics, pregnancy characteristics, intrapartum monitoring, mode of delivery, neonatal outcomes (Apgar score < 7 at 5 minutes, umbilical cord artery pH < 7.10, neonatal intensive care unit admission) and maternal outcomes, with regard to the presence of tachysystole. The association between tachysystole and cesarean section was evaluated after adjusting for potential confounders by a modified Poisson regression model, expressed as an adjusted risk ratio and 95% confidence intervals. Results A total of 140 women (31.4%) presented with tachysystole. The median duration of tachysystole was 2 hours 12 minutes. The rate of cesarean section was 25.0% (N=35) among patients with tachysystole and 19.6% (N=60) for those without tachysystole. Presence of tachysystole during induction of labor with misoprostol vaginal inserts was not associated with cesarean section (adjusted risk ratio,1.0; 95% confidence interval, 0.7 to 1.4). Neonatal and maternal outcomes were similar between mothers who did and did not experience tachysystole. Conclusions This study illustrates that tachysystole is not associated with an increased risk of cesarean section after induction of labor by misoprostol vaginal inserts. The impact of excessive uterine activity on the fetal wellbeing defined by the frequency of uterine contraction alone is probably insufficient. Further research on the development of accurate measures of uterine contractility is necessary to better understand its effect on fetal well-being. Maternal & Fetal Medicine Tachysystole cesarean section cervical ripening misoprostol vaginal inserts neonatal outcomes uterine activity uterine contractions Figures Figure 1 Background Induction of labor is a common obstetrical intervention. The rate of induction of labor in the United States has increased in the last twenty years from 9.5% to 23% of births. 1 A misoprostol vaginal insert, releasing 7 mcg per hour, was introduced to the market in 2014. It is the only licensed prostaglandin E1 analogue approved for induction of labor in many countries. However, compared to other means of induction of labor, increased rates of tachysystole with misoprostol vaginal inserts (MVI) have been reported by several authors. 2–4 Presence of tachysystole during induction of labor is a concern as it is feared to lead to fetal blood deoxygenation due to decreased placental perfusion. 5 This in turn could lead to non-reassuring fetal heart traces, fetal acidosis, and hence higher rates of medical intervention and poorer neonatal outcomes. 5 Despite the high frequency of tachysystole after induction of labor with MVI, no difference in cesarean section rate or neonatal outcome has been observed between MVI and other induction methods. 2–4 Currently, there is conflicting evidence regarding the clinical impact of tachysystole, as some authors have reported an increase in cesarean section rates, operative vaginal delivery and neonatal morbidity 6–8 while others found no significant differences. 9–11 More information is therefore needed on the association between tachysystole and progression to cesarean section. Furthermore, a study illustrated that managing cases of uterine tachysystole with fetal heart rate changes was more challenging due to the longer half-life of MVIs (approximately 40 minutes). 14 The optimal approach to manage concurrent tachysystole and fetal heart rate alterations after induction of labor is as yet undetermined. The aim of our study was to evaluate if the presence of tachysystole after induction of labor by MVI is associated with an increased risk of cesarean section and unfavorable maternal or neonatal outcomes. Methods Study population We conducted a retrospective cohort study at the obstetrics service of the University Hospital of Lausanne, between May 2016 and May 2017. We included all pregnant women above 37 weeks of gestation and parity of three or less, admitted for induction of labor by MVI. The exclusion criteria were the following: women under 18 years old, previous uterine scar, uterine malformation, application of more than one MVI, pregnancy complicated by non-vertex presentation, modified Bishop’s score ≥7, multiple gestation, major fetal anomaly, non-viable foetus, pre-existing contraindications for labor or vaginal delivery, and cases where the paper fetal heart trace was unavailable. Demographic, obstetrical and neonatal characteristics were gathered from the admission chart available on the hospital electronic database. The following data were recorded: maternal age, parity, gestational age, maternal BMI, maternal smoking, modified Bishop’s score at admission, indication for induction of labor, presence of tachysystole, duration of tachysystole, use of tocolytics, fetal heart patterns, use of early epidural anesthesia, mode of delivery, time of delivery from the onset of induction, presence of meconium stained amniotic fluid, postpartum hemorrhage (≥ 500 ml after vaginal delivery and ≥ 1000 ml after cesarean section), neonatal umbilical cord blood gases and Apgar score at birth, transfer to neonatal intensive care unit (NICU). The MVI was applied to the posterior fornix. The vaginal insert was extracted under the following conditions: onset of active labor, painful regular contractions, tachysystole, non-reassuring fetal heart monitoring, at 24 hours’ post insertion, or at maternal request. Exposure The contractions patterns were independently reviewed by two authors (JS, DD), and classified according to the American College of Obstetrics and Gynecology and the National Institute of Child Health and Human Development workshop report. 13,14 During the review process, authors were blinded for the mode of delivery and the neonatal issues. Any assessment discordances or difficulty of interpretation, were discussed between the authors. Tachysystole was defined as ≥6 contractions per 10 minutes, averaged over a 30-minute window. 13,14 Outcomes A positive primary outcome was considered for every patient with cesarean section noted in their chart as the mode of delivery. In our service, fetal heart rate monitoring is recorded at regular intervals before labor (20 minutes before insertion; 1 hour following insertion; every 4 hours thereafter), as well as in cases of painful uterine contractions. During labor, a continuous fetal heart rate monitoring is performed. Following the same blinded review process as for the definition of tachysystole, fetal heart patterns were assessed using the available information. Non-reassuring fetal heart rate patterns, a secondary outcome, were defined as either Category II or Category III using the classification of the American College of Obstetrics and Gynecology and the National Institute of Child Health and Human Development workshop report. 13,14 The use of tocolytics with time to resolution after administration was reported as another secondary outcome. Intrapartum fetal resuscitation was performed by rolling the patient to their left side, with administration of tocolytics in case of tachysystole associated with a Category III fetal heart pattern, in accordance with our unit’s protocol. Tocolysis was effected using either atosiban or hexoprenaline at the physician’s discretion. Postpartum hemorrhage, transfer to neonatal intensive care unit (NICU), umbilical artery pH ≤ 7.10, and five-minute Apgar score < 7 were considered as other positive secondary outcomes. Statistical analysis Student t- test and Chi-square or Fisher’s exact test were used for comparison of continuous and categorical data, respectively. Cohen’s kappa coefficient was used 15 to assess interobserver agreement after fetal heart and contractions patterns review. A Wilcoxon rank sum test was used to compare resolution time of tachysystole between the types of tocolytics. Proportions were compared for potential confounders among women with tachysystole or without. Absolute risks and unadjusted risk ratios (RR) with their 95% confidence interval (CI) were calculated. Adjusted RR (aRR) and 95% CI were estimated using generalized linear models (Poisson regression with robust variance estimates). All analyses were performed using STATA software (version 14IC; Stata corporation, College Station, TX). Results During the study period, amongst 3428 deliveries, there were 489 patients (14.3%) induced by MVI. The overall induction of labor rate was 20.2%. A total of 446 patients were included in the analysis, as 43 women (8.8%) did not meet our inclusion criteria as illustrated in Figure 1. In the cohort of enrolled patients, 296 (66.4%) were nulliparous. The mean maternal age was 31.6 years, ranging from 18 to 49, and the mean gestational age was 40.2 weeks, ranging from 37 to 42. The most common indication for induction of labor was post-term pregnancy in 126 women (28.3%), followed by premature rupture of membranes in 110 women (24.7%) anad oligohydramnios in 37 women (8.7%). 32 women (7.2%) were induced at their request. The median time between onset of induction of labor and any mode of delivery was 15 hours 6 minutes. The median time between insertion and removal of MVI was 7 hours. Amongst the included women, 140 (31.4%) presented with an episode of tachysystole. Demographics and baseline characteristics of the study population were compared according to the presence of tachysystole (Table 1). There were several differences in the baseline characteristics between the groups. Women with tachysystole were more likely to present with the following characteristics: younger age, older gestational age at induction, lower BMI, post-term pregnancy, oligohydramnios, cholestasis of pregnancy, Bishop’s modified score < 4 at induction, use of tocolytics, meconium stained amniotic fluid, and use of epidural anesthesia. The median duration of tachysystole was 2 hours 12 minutes. Tachysystole arose after removal of the MVI in 33 women (23.6%). Tocolytics were administered to 21 women (15.0%) who presented with tachysystole and category III fetal heart tracing; 9 women (42.9%) received atosiban while 12 (57.1%) received hexoprenaline. 17 women (5.6%) without tachysystole received tocolytics; hexoprenaline in all cases. No significant difference in rates of cesarean section between the administration of atosiban compared to hexoprenaline was observed (46.2% vs 53.9%, p = 0.70), nor in the difference in time to resolution of tachysytole (1 hour 12 minutes vs 1 hour 43 minutes, p = 0.93). The risk of cesarean section was 25.0% in the tachysystole group and 19.6% in the other group (p = 0.20). The unadjusted RR for cesarean section associated with the presence of tachysystole after induction of labor vs absence of tachysystole was 1.4 (95% CI, 0.8 to 2.2). After adjustment for confounders using generalized linear models, the adjusted RR was 1.0 (95% CI, 0.7 to 1.4) (Table 2). A satisfactory agreement between the two reviewers with regards to the classification of the contraction patterns was observed, with a Cohen’s kappa value of 85% (CI 95%: 0.79 to 0.91). Women who experienced tachysystole were more likely to present non-reassuring fetal heart monitoring during induction of labor or labor (aRR, 3.7; 95% CI, 3.0 to 4.7). However, no associations were found between unfavorable neonatal outcomes and tachysystole: Apgar scores < 7 at 5 minutes (aRR, 1.3; 95% CI, 0.8 to 2.2), cord arterial pH < 7.10 (aRR, 0.9; 95% CI, 0.6 to 1.3) and NICU admission (aRR, 1.0; 95% CI, 0.7 to 1.6). Furthermore, women with tachysystole were not at increased risk of postpartum hemorrhage (aRR, 1.1; 95% CI, 0.8 to 1.6) (Table 3). Discussion In this retrospective cohort study, we did not observe an association between tachysystole after induction of labor by misoprostol vaginal inserts and cesarean section, despite its frequent occurrence (31.4%). Non-reassuring fetal heart patterns during induction of labor or labor were more common amongst women who presented with tachysystole; however, tachysystole was not found to be associated with unfavorable neonatal outcomes. Concerning the management of tachysystole, only a sixth of women who presented with this condition required tocolysis. We did not observe any significant difference between atosiban and hexoprenaline as regards cesarean section avoidance and time to resolution of tachysystole. Different incidences of tachysystole after induction of labor by MVI have been described in recently published studies, ranging from 22.8% to 49.1%.2,3,16,17 This discrepancy could be explained by the different definitions used for tachysystole. Since 2009, the American College of Obstetrics and Gynecology defines tachysystole as ≥ 6 contractions in 3 consecutive 10-minute windows over a 30-minute period, a definition employed in our study.13 Based on a retrospective fetal oxygenation analysis on a small cohort, Simpson et al illustrated a 20 % decrease in fetal oxygenation at 30 minutes in women with 5 or more contractions.18 However, in a large prospective cohort of patients induced by 100 mcg of misoprostol, a definition of tachysystole as more than 6 contractions per 10 minutes, compared to 5, was significantly associated with an increase in fetal heart rate decelerations, concurring with the American national guidelines’ definition.9 A more restrictive definition, as used in the phase 3 clinical trial, would thus result in a perceived increased rate of tachysystole. Another explanation for the difference in rates of tachysystole lies in the time of removal of the MVI, due to the relatively long half-life of MVIs.12 In our study the median time from insertion to removal was 7 hours, compared to 12 hours in the phase 3 clinical trial. Tachysystole arose in 23.6% of women in our cohort following removal of the MVI, highlighting the pertinence of the timing of MVI removal in tachysystole prevention. Apart from the varying rate of tachysystole between studies, the critical question remains the impact of tachysystole on maternal and fetal outcomes. In our study, adverse neonatal outcomes (cord blood pH, Apgar score or admission to NICU) were not associated with the presence of tachysystole. This was in line with recent findings.3,16,17,19–21 Similar results were observed concerning the rate of postpartum hemorrhage. Why do some women experience tachysystole for hours with no impact on the fetal heart pattern, while others rapidly manifest grave repercussions? Current evidence cannot provide an adequate answer. Heuser et al. retrospectively examined 48,529 women who underwent spontaneous, induced or augmented labor during a 28-month period.6 11% of women presented with tachysystole, with an associated increase in operative delivery, NICU admissions and composite adverse neonatal outcomes. However, 60% of women presenting with tachysystole did not necessitate any interventions or present fetal heart rate alterations. In another retrospective study, by Ahmed et al., 11% of 8008 women in spontaneous labor presented with tachysystole.8 This study illustrated an increased risk of cesarean section for non-reassuring fetal heart tracings and NICU admissions. The overall absolute risk was increased by only 2% or less, as 96% of women with tachysystole presented normal fetal heart monitoring. For both studies there were no individual associations between tachysystole and low Apgar score, and umbilical cord pH data were unavailable. Frey et al. conducted a case–control study of 2355 women, and showed that while tachysystole was common in cases of unfavorable composite neonatal outcomes, rates of tachysystole were not significantly different compared to women with normal umbilical artery pH.22 In line with our results, Bofill et al. demonstrated, in an analysis of six randomized clinical trials involving 905 women undergoing induction or augmentation of labor, that while non-reassuring fetal heart tracings were more common in the tachysystole group, there were no adverse effects observed on Apgar scores, umbilical cord pH or NICU admissions.11 Two separate studies examining tachysystole have not shown greater incidence of low Apgar scores, umbilical artery pH or other adverse neonatal outcomes:9,10 Stewart et al,9 who examined cases in the initial 4 hours of induction of labor, and Smith et al,10 who investigated cases during the final 4 days before delivery. Clinical debate on the issue centers on uterine contraction frequency, but perhaps examination of uterine contractile force bears more importance. Could the compression of the spiral arteries leading to reduced fetal oxygenation be a consequence, not alone of tachysystole, but also of differences in uterine contraction intensity? It is our belief that defining tachysystole only by the number of contractions per 10 minute intervals is not a reliable marker to predict adverse neonatal and maternal outcomes, as external tocodynamometers are useless in the measurement of uterine contractile force or baseline uterine tone.23 Baker et al demonstrated by using intrauterine pressure catheter that an increased uterine activity was associated with lower umbilical cord arterial.7 In contrast, a Cochrane review found insufficient evidence for the routine use of intrauterine pressure catheter during induction of labor or augmentation with oxyctocin as it did not show an improvement in maternal and neonatal outcomes,24 with some complications reported.25 Recently, a promising non-invasive alternative technique for uterine contraction monitoring has been developed. Electrohysterography measures the uterine electrical currents through contact electrodes placed on the abdomen, and has higher sensitivity than external tocodynamometers for uterine contraction detection.26 Electrohysterography has been investigated as a tool to measure intrauterine pressure,27 and should discriminate clinical settings eg labor vs non-labor,28 prediction of preterm deliveries,29 or prostaglandins effect on uterine activity during induction of labor.30 With further study, electrohysterography monitoring could provide further insight on uterine contractions’ capacity to alter placental perfusion, and thus fetal outcomes. Amongst the strengths of our research, our patient cohort presented tachysystole at a high incidence and of relatively long duration, with these fetuses exposed to greater uterine activity than those in any comparable study. Our research was not limited to specific intrapartum periods, instead encompassing the entire labor process. Fetal heart trace analysis was performed according to current definitions of tachysystole. Our work is homogenic, using a single protocol of induction of labor in a tertiary center. Furthermore, this study is original as, contrary to some other works reporting on tachysystole, we report the tocolytic agents administered, and their impact.2,3,16,17 The major limitation of this study is its retrospective design. Retrospective chart review inhibits our capacity to control for other potential confounding factors. We have endeavored to mitigate this by dual independent analysis and correlation testing. Hidden bias may be produced by charts presenting deficient data. Our study was also limited by the fact that we were unable to retrieve the fetal heart traces of 30 (6.1%) patients. Conclusions In summary, we illustrated that tachysystole after induction of labor by MVI is not associated to an increased rate of cesarean delivery. However, the impact of excessive uterine activity on the fetal wellbeing defined by the frequency of uterine contraction alone is probably insufficient. While prediction of neonatal outcomes according to fetal heart patterns is currently in vogue, the repercussions of uterine activity on these outcomes has largely been ignored. Further attention is required to the characterization of excessive uterine activity, and the effective application of such knowledge by the obstetrician to optimize the safety of mother and child. Abbreviations aRR adjusted risk ratios CI confidence interval NICU neonatal intensive care unit MVI misoprostol vaginal inserts RR unadjusted risk ratios Declarations Ethical approval and consent for publication: The study was approved by the local IRB (Ethical Commission of the Canton of Vaud, Switzerland, 2018-01761), on November 21 st 2018. As routinely collected data was accessed, no written consent from women was obtained. Availability of data and materials : The dataset used and/or analysed during the current study are available from the corresponding author on reasonable request. Disclosure of interests: The authors report no conflict of interest Funding: None Authors’ contributions: Conception and design : JS, DD and YV. Data collection: JS. Data analysis: JS, DD and AP. Manuscript drafting: JS. Revision of the manuscript and/or editing: YV, DB, AP, DD. All authors read and approved of the final manuscript. Acknowledgements: The authors would like to thank Patrick Callinan for his help with the translation of the original manuscript. References 1 Martin JA, Hamilton BE, Osterman MJ, Curtin SC, Matthews TJ. Births: final data for 2013. Natl Vital Stat Rep 2015; 64: 1–65. 2 Wing DA, Brown R, Plante LA, Miller H, Rugarn O, Powers BL. Misoprostol vaginal insert and time to vaginal delivery: a randomized controlled trial. Obstet Gynecol 2013; 122: 201–9. 3 Bolla D, Weissleder SV, Radan A-P, et al. Misoprostol vaginal insert versus misoprostol vaginal tablets for the induction of labour: a cohort study. BMC Pregnancy Childbirth 2018; 18: 149. 4 Hokkila E, Kruit H, Rahkonen L, et al. The efficacy of misoprostol vaginal insert compared with oral misoprostol in the induction of labor of nulliparous women: A randomized national multicenter trial. Acta Obstet Gynecol Scand 2019; published online Feb 16. DOI:10.1111/aogs.13580. 5 Hobson SR, Abdelmalek MZ, Farine D. Update on uterine tachysystole. J Perinat Med 2018; published online Oct 20. DOI:10.1515/jpm-2018-0175. 6 Heuser CC, Knight S, Esplin MS, et al. Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings. Am J Obstet Gynecol 2013; 209: 32.e1-6. 7 Bakker PC a. M, Kurver PHJ, Kuik DJ, Van Geijn HP. Elevated uterine activity increases the risk of fetal acidosis at birth. Am J Obstet Gynecol 2007; 196: 313.e1-6. 8 Ahmed AI, Zhu L, Aldhaheri S, Sakr S, Minkoff H, Haberman S. Uterine tachysystole in spontaneous labor at term. J Matern-Fetal Neonatal Med 2016; 29: 3335–9. 9 Stewart RD, Bleich AT, Lo JY, Alexander JM, McIntire DD, Leveno KJ. Defining uterine tachysystole: how much is too much? Am J Obstet Gynecol 2012; 207: 290.e1-6. 10 Smith S, Zacharias J, Lucas V, Warrick PA, Hamilton EF. Clinical associations with uterine tachysystole. J Matern-Fetal Neonatal Med 2014; 27: 709–13. 11 Bofill JA, Darby MM, Castillo J, Sawardecker SU, Magann EF, Morrison JC. Tachysystole Following Cervical Ripening and Induction of Labor Is Not Associated with Adverse Outcomes. Gynecol Obstet Invest 2017; 82: 487–93. 12 Rugarn O, Tipping D, Powers B, Wing DA. Induction of labour with retrievable prostaglandin vaginal inserts: outcomes following retrieval due to an intrapartum adverse event. BJOG 2017; 124: 796–803. 13 American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. Obstet Gynecol 2009; 114: 192–202. 14 Macones GA, Hankins GDV, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008; 37: 510–5. 15 Fermanian J. [Measurement of agreement between 2 judges. Qualitative cases]. Rev Epidemiol Sante Publique 1984; 32: 140–7. 16 Redling K, Schaedelin S, Huhn EA, Hoesli I. Efficacy and safety of misoprostol vaginal insert vs. oral misoprostol for induction of labor. J Perinat Med 2018; published online Sept 4. DOI:10.1515/jpm-2018-0128. 17 Rankin K, Chodankar R, Raymond K, Bhaskar S. Misoprostol vaginal insert versus dinoprostone vaginal insert: A comparison of labour and delivery outcomes. Eur J Obstet Gynecol Reprod Biol 2018; published online July 25. DOI:10.1016/j.ejogrb.2018.07.025. 18 Simpson KR, James DC. Effects of oxytocin-induced uterine hyperstimulation during labor on fetal oxygen status and fetal heart rate patterns. Am J Obstet Gynecol 2008; 199: 34.e1-5. 19 Marsdal KE, Sørbye IK, Gaudernack LC, Lukasse M. A comparison of misoprostol vaginal insert and misoprostol vaginal tablets for induction of labor in nulliparous women: a retrospective cohort study. BMC Pregnancy Childbirth 2018; 18: 11. 20 Mayer RB, Oppelt P, Shebl O, Pömer J, Allerstorfer C, Weiss C. Initial clinical experience with a misoprostol vaginal insert in comparison with a dinoprostone insert for inducing labor. Eur J Obstet Gynecol Reprod Biol 2016; 200: 89–93. 21 Schmidt M, Neophytou M, Hars O, Freudenberg J, Kühnert M. Clinical experience with misoprostol vaginal insert for induction of labor: a prospective clinical observational study. Arch Gynecol Obstet 2018; published online Oct 29. DOI:10.1007/s00404-018-4942-y. 22 Frey HA, Tuuli MG, Roehl KA, Odibo AO, Macones GA, Cahill AG. Can contraction patterns predict neonatal outcomes? J Matern-Fetal Neonatal Med 2014; 27: 1422–7. 23 Steer PJ. Standards in fetal monitoring--practical requirements for uterine activity measurement and recording. BJOGl 1993; 100 Suppl 9: 32–6. 24 Bakker JJH, Janssen PF, van Halem K, et al. Internal versus external tocodynamometry during induced or augmented labour. Cochrane Database Syst Rev 2013; : CD006947. 25 Bakker PCAM, Van Rijswijk S, Van Rijsiwijk S, van Geijn HP. Uterine activity monitoring during labor. J Perinat Med 2007; 35: 468–77. 26 Vlemminx MWC, Thijssen KMJ, Bajlekov GI, Dieleman JP, Van Der Hout-Van Der Jagt MB, Oei SG. Electrohysterography for uterine monitoring during term labour compared to external tocodynamometry and intra-uterine pressure catheter. Eur J Obstet Gynecol Reprod Biol 2017; 215: 197–205. 27 Euliano T, Skowronski M, Marossero D, Shuster J, Edwards R. Prediction of intrauterine pressure waveform from transabdominal electrohysterography. J Matern-Fetal Neonatal Med 2006; 19: 811–6. 28 Alberola-Rubio J, Garcia-Casado J, Prats-Boluda G, et al. Prediction of labor onset type: Spontaneous vs induced; role of electrohysterography? Comput Methods Programs Biomed 2017; 144: 127–33. 29 Garcia-Casado J, Ye-Lin Y, Prats-Boluda G, Mas-Cabo J, Alberola-Rubio J, Perales A. Electrohysterography in the diagnosis of preterm birth: a review. Physiol Meas 2018; 39: 02TR01. 30 Benalcazar-Parra C, Ye-Lin Y, Garcia-Casado J, et al. Electrohysterographic characterization of the uterine myoelectrical response to labor induction drugs. Med Eng Phys 2018; 56: 27–35. Tables Table 1. Demographic and baseline characteristics of the study population Tachysystole Yes n = 140 No n = 306 P-value Maternal age, years 0.001 = 35 24 (17.1) 90 (29.4) Gestational age at induction, weeks 0.06 37 4 (2.9) 10 (3.3) 38 16 (11.4) 27 (8.8) 39 18 (12.9) 54 (17.6) 40 19 (13.6) 70 (22.9) > 41 83 (59.3) 145 (47.4) Nulliparity 98 (70.0) 198 (64.7) 0.27 BMI, kg/m 2 0.14 18.5-24.9 12 (8.6) 26 (8.5) 25-29.9 115 (82.1) 230 (75.2) >=30 13 (9.3) 50 (16.3) Indication for induction 0.05 Post-term pregnancy 50 (35.7) 76 (24.8) Rupture of membrane 20 (14.3) 90 (29.4) Diabetes 8 (5.7) 21 (6.9) Oligohydramnios 13 (9.3) 26 (8.5) Foetal movement diminution 3 (2.1) 9 (2.9) Preeclampsia/Hypertension 5 (3.6) 14 (4.6) Suspected macrosomia 8 (5.7) 14 (4.6) Maternal request 11 (7.9) 21 (6.9) Cholestasis of pregnancy 4 (2.9) 3 (1.0) Other 18 (12.9) 32 (10.5) Modified Bishop’s score > 4 11 (7.9) 39 (12.7) 0.13 Use of tobacco during pregnancy 19 (13.6) 46 (15.0) 0.63 Epidural anesthesia 110 (78.6) 212 (69.3) 0.05 Meconium stained amniotic fluid 37 (26.4) 63 (20.6) 0.18 Tocolysis 21 (15.0) 17 (5.6) 0.001 All data shown as n (%) value obtained via Chi-square test of Fisher’s exact test as appropriate. BMI, body mass index Table 2. Adjusted risk ratio for cesarean section among patients induced with misoprostol vaginal inserts in the presence of tachysystole Caesarean section n (%) RR (95% CI) Adjusted RR (95% CI) a Tachysystole 35 (25.0) 1.4 (0.8-2.2) 1.0 (0.7-1.4) a Adjusted for maternal age, gestational age, indication of induction, body mass index, modified Bishop’s score > 4, use of epidural anesthesia, presence of meconium stained amniotic fluid by a modified Poisson regression. RR, risk ratio; CI , confidence interval Table 3. Intrapartum monitoring, neonatal and maternal outcomes Tachysystole value a Yes N = 140 No N =306 RR (95% CI) Adjusted RR (95% CI) a NRFT 52 (37.1) 84 (27.5) 15.9 (8.3-30.5) 3.7 (3.0-4.7) Neonatal outcomes Apgar < 7 at 5 minutes 7 (5.0) 6 (2.0) 2.6 (0.9-8.0) 1.3 (0.8-2.2) Cord artery pH < 7.10 14 (10.0) 17 (5.6) 1.9 (0.9-4.0) 0.9 (0.6-1.3) NICU admission 18 (12.9) 26 (8.5) 1.6 (0.8-3.0) 1.0 (0.7-1.6) Maternal outcome Postpartum hemorrhage 31 (10.1) 16 (11.4) 1.1 (0.6-2.2) 1.1 (0.8-1.6) All data shown as n (%). Cite Share Download PDF Status: Published Journal Publication published 01 Jun, 2020 Read the published version in European Journal of Obstetrics & Gynecology and Reproductive Biology → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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The rate of induction of labor in the United States has increased in the last twenty years from 9.5% to 23% of births.\u003csup\u003e1\u003c/sup\u003e A misoprostol vaginal insert, releasing 7 mcg per hour, was introduced to the market in 2014. It is the only licensed prostaglandin E1 analogue approved for induction of labor in many countries. However, compared to other means of induction of labor, increased rates of tachysystole with misoprostol vaginal inserts (MVI) have been reported by several authors.\u003csup\u003e2\u0026ndash;4\u003c/sup\u003e \u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePresence of tachysystole during induction of labor is a concern as it is feared to lead to fetal blood deoxygenation due to decreased placental perfusion.\u003csup\u003e5\u003c/sup\u003e This in turn could lead to non-reassuring fetal heart traces, fetal acidosis, and hence higher rates of medical intervention and poorer neonatal outcomes.\u003csup\u003e5\u003c/sup\u003e Despite the high frequency of tachysystole after induction of labor with MVI, no difference in cesarean section rate or neonatal outcome has been observed between MVI and other induction methods.\u003csup\u003e2\u0026ndash;4\u003c/sup\u003e Currently, there is conflicting evidence regarding the clinical impact of tachysystole, as some authors have reported an increase in cesarean section rates, operative vaginal delivery and neonatal morbidity\u003csup\u003e6\u0026ndash;8\u003c/sup\u003e while others found no significant differences.\u003csup\u003e9\u0026ndash;11\u003c/sup\u003e More information is therefore needed on the association between tachysystole and progression to cesarean section. Furthermore, a study illustrated that managing cases of uterine tachysystole with fetal heart rate changes was more challenging due to the longer half-life of MVIs (approximately 40 minutes).\u003csup\u003e14\u003c/sup\u003e The optimal approach to manage concurrent tachysystole and fetal heart rate alterations after induction of labor is as yet undetermined.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe aim of our study was to evaluate if the presence of tachysystole after induction of labor by MVI is associated with an increased risk of cesarean section and unfavorable maternal or neonatal outcomes.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe conducted a retrospective cohort study at the obstetrics service of the University Hospital of Lausanne, between May 2016 and May 2017. We included all pregnant women above 37 weeks of gestation and parity of three or less, admitted for induction of labor by MVI. The exclusion criteria were the following: women under 18 years old, previous uterine scar, uterine malformation, application of more than one MVI, pregnancy complicated by non-vertex presentation, modified Bishop\u0026rsquo;s score \u0026ge;7, multiple gestation, major fetal anomaly, non-viable foetus, pre-existing contraindications for labor or vaginal delivery, and cases where the paper fetal heart trace was unavailable.\u003c/p\u003e\n\u003cp\u003eDemographic, obstetrical and neonatal characteristics were gathered from the admission chart available on the hospital electronic database. The following data were recorded: maternal age, parity, gestational age, maternal BMI, maternal smoking, modified Bishop\u0026rsquo;s score at admission, indication for induction of labor, presence of tachysystole, duration of tachysystole, use of tocolytics, fetal heart patterns, use of early epidural anesthesia, mode of delivery, time of delivery from the onset of induction, presence of meconium stained amniotic fluid, postpartum hemorrhage (\u0026ge; 500 ml after vaginal delivery and \u0026ge; 1000 ml after cesarean section), neonatal umbilical cord blood gases and Apgar score at birth, transfer to neonatal intensive care unit (NICU).\u003c/p\u003e\n\u003cp\u003eThe MVI was applied to the posterior fornix. The vaginal insert was extracted under the following conditions: onset of active labor, painful regular contractions, tachysystole, non-reassuring fetal heart monitoring, at 24 hours\u0026rsquo; post insertion, or at maternal request.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExposure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe contractions patterns were independently reviewed by two authors (JS, DD), and classified according to the American College of Obstetrics and Gynecology and the National Institute of Child Health and Human Development workshop report.\u003csup\u003e13,14\u003c/sup\u003e During the review process, authors were blinded for the mode of delivery and the neonatal issues. Any assessment discordances or difficulty of interpretation, were discussed between the authors. Tachysystole was defined as \u0026ge;6 contractions per 10 minutes, averaged over a 30-minute window.\u003csup\u003e13,14\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcomes \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA positive primary outcome was considered for every patient with cesarean section noted in their chart as the mode of delivery.\u003c/p\u003e\n\u003cp\u003eIn our service, fetal heart rate monitoring is recorded at regular intervals before labor (20 minutes before insertion; 1 hour following insertion; every 4 hours thereafter), as well as in cases of painful uterine contractions. During labor, a continuous fetal heart rate monitoring is performed. Following the same blinded review process as for the definition of tachysystole, fetal heart patterns were assessed using the available information. Non-reassuring fetal heart rate patterns, a secondary outcome, were defined as either Category II or Category III using the classification of the American College of Obstetrics and Gynecology and the National Institute of Child Health and Human Development workshop report.\u003csup\u003e13,14\u003c/sup\u003e The use of tocolytics with time to resolution after administration was reported as another secondary outcome. Intrapartum fetal resuscitation was performed by rolling the patient to their left side, with administration of tocolytics in case of tachysystole associated with a Category III fetal heart pattern, in accordance with our unit\u0026rsquo;s protocol. Tocolysis was effected using either atosiban or hexoprenaline at the physician\u0026rsquo;s discretion.\u003c/p\u003e\n\u003cp\u003ePostpartum hemorrhage, transfer to neonatal intensive care unit (NICU), umbilical artery pH \u0026le; 7.10, and five-minute Apgar score \u0026lt; 7 were considered as other positive secondary outcomes.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStudent \u003cem\u003et-\u003c/em\u003etest and Chi-square or Fisher\u0026rsquo;s exact test were used for comparison of continuous and categorical data, respectively. Cohen\u0026rsquo;s kappa coefficient was used\u003csup\u003e15\u003c/sup\u003e to assess interobserver agreement after fetal heart and contractions patterns review. A Wilcoxon rank sum test was used to compare resolution time of tachysystole between the types of tocolytics.\u003c/p\u003e\n\u003cp\u003eProportions were compared for potential confounders among women with tachysystole or without. Absolute risks and unadjusted risk ratios (RR) with their 95% confidence interval (CI) were calculated. Adjusted RR (aRR) and 95% CI were estimated using generalized linear models (Poisson regression with robust variance estimates). All analyses were performed using STATA software (version 14IC; Stata corporation, College Station, TX).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eDuring the study period, amongst 3428 deliveries, there were 489 patients (14.3%) induced by MVI. The overall induction of labor rate was 20.2%. A total of 446 patients were included in the analysis, as 43 women (8.8%) did not meet our inclusion criteria as illustrated in Figure 1.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the cohort of enrolled patients, 296 (66.4%) were nulliparous. The mean maternal age was 31.6 years, ranging from 18 to 49, and the mean gestational age was 40.2 weeks, ranging from 37 to 42. The most common indication for induction of labor was post-term pregnancy in 126 women (28.3%), followed by premature rupture of membranes in 110 women (24.7%) anad oligohydramnios in 37 women (8.7%). 32 women (7.2%) were induced at their request. The median time between onset of induction of labor and any mode of delivery was 15 hours 6 minutes. The median time between insertion and removal of MVI was 7 hours.\u003c/p\u003e\n\u003cp\u003eAmongst the included women, 140 (31.4%) presented with an episode of tachysystole. Demographics and baseline characteristics of the study population were compared according to the presence of tachysystole (Table 1). There were several differences in the baseline characteristics between the groups. Women with tachysystole were more likely to present with the following characteristics: younger age, older gestational age at induction, lower BMI, post-term pregnancy, oligohydramnios, cholestasis of pregnancy, Bishop\u0026rsquo;s modified score \u0026lt; 4 at induction, use of tocolytics, meconium stained amniotic fluid, and use of epidural anesthesia.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe median duration of tachysystole was 2 hours 12 minutes. Tachysystole arose after removal of the MVI in 33 women (23.6%). Tocolytics were administered to 21 women (15.0%) who presented with tachysystole and category III fetal heart tracing; 9 women (42.9%) received atosiban while 12 (57.1%) received hexoprenaline. 17 women (5.6%) without tachysystole received tocolytics; hexoprenaline in all cases.\u003c/p\u003e\n\u003cp\u003eNo significant difference in rates of cesarean section between the administration of atosiban compared to hexoprenaline was observed (46.2% vs 53.9%, p = 0.70), nor in the difference in time to resolution of tachysytole (1 hour 12 minutes vs 1 hour 43 minutes, p\u003cem\u003e =\u003c/em\u003e 0.93).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe risk of cesarean section was 25.0% in the tachysystole group and 19.6% in the other group (p = 0.20). The unadjusted RR for cesarean section associated with the presence of tachysystole after induction of labor vs absence of tachysystole was 1.4 (95% CI, 0.8 to 2.2). After adjustment for confounders using generalized linear models, the adjusted RR was 1.0 (95% CI, 0.7 to 1.4) (Table 2).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA satisfactory agreement between the two reviewers with regards to the classification of the contraction patterns was observed, with a Cohen\u0026rsquo;s kappa value of 85% (CI 95%: 0.79 to 0.91).\u003c/p\u003e\n\u003cp\u003eWomen who experienced tachysystole were more likely to present non-reassuring fetal heart monitoring during induction of labor or labor (aRR, 3.7; 95% CI, 3.0 to 4.7). However, no associations were found between unfavorable neonatal outcomes and tachysystole: Apgar scores \u0026lt; 7 at 5 minutes (aRR, 1.3; 95% CI, 0.8 to 2.2), cord arterial pH \u0026lt; 7.10 (aRR, 0.9; 95% CI, 0.6 to 1.3) and NICU admission (aRR, 1.0; 95% CI, 0.7 to 1.6). Furthermore, women with tachysystole were not at increased risk of postpartum hemorrhage (aRR, 1.1; 95% CI, 0.8 to 1.6) (Table 3).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective cohort study, we did not observe an association between tachysystole after induction of labor by misoprostol vaginal inserts and cesarean section, despite its frequent occurrence (31.4%). Non-reassuring fetal heart patterns during induction of labor or labor were more common amongst women who presented with tachysystole; however, tachysystole was not found to be associated with unfavorable neonatal outcomes. Concerning the management of tachysystole, only a sixth of women who presented with this condition required tocolysis. We did not observe any significant difference between atosiban and hexoprenaline as regards cesarean section avoidance and time to resolution of tachysystole.\u003c/p\u003e\n\u003cp\u003eDifferent incidences of tachysystole after induction of labor by MVI have been described in recently published studies, ranging from 22.8% to 49.1%.2,3,16,17 This discrepancy could be explained by the different definitions used for tachysystole. Since 2009, the American College of Obstetrics and Gynecology defines tachysystole as \u0026ge; 6 contractions in 3 consecutive 10-minute windows over a 30-minute period, a definition employed in our study.13 Based on a retrospective fetal oxygenation analysis on a small cohort, Simpson et al illustrated a 20 % decrease in fetal oxygenation at 30 minutes in women with 5 or more contractions.18 However, in a large prospective cohort of patients induced by 100 mcg of misoprostol, a definition of tachysystole as more than 6 contractions per 10 minutes, compared to 5, was significantly associated with an increase in fetal heart rate decelerations, concurring with the American national guidelines\u0026rsquo; definition.9 A more restrictive definition, as used in the phase 3 clinical trial, would thus result in a perceived increased rate of tachysystole. Another explanation for the difference in rates of tachysystole lies in the time of removal of the MVI, due to the relatively long half-life of MVIs.12 In our study the median time from insertion to removal was 7 hours, compared to 12 hours in the phase 3 clinical trial. Tachysystole arose in 23.6% of women in our cohort following removal of the MVI, highlighting the pertinence of the timing of MVI removal in tachysystole prevention.\u003c/p\u003e\n\u003cp\u003eApart from the varying rate of tachysystole between studies, the critical question remains the impact of tachysystole on maternal and fetal outcomes. In our study, adverse neonatal outcomes (cord blood pH, Apgar score or admission to NICU) were not associated with the presence of tachysystole. This was in line with recent findings.3,16,17,19\u0026ndash;21 Similar results were observed concerning the rate of postpartum hemorrhage.\u003c/p\u003e\n\u003cp\u003eWhy do some women experience tachysystole for hours with no impact on the fetal heart pattern, while others rapidly manifest grave repercussions? Current evidence cannot provide an adequate answer. Heuser et al. retrospectively examined 48,529 women who underwent spontaneous, induced or augmented labor during a 28-month period.6 11% of women presented with tachysystole, with an associated increase in operative delivery, NICU admissions and composite adverse neonatal outcomes. However, 60% of women presenting with tachysystole did not necessitate any interventions or present fetal heart rate alterations. In another retrospective study, by Ahmed et al., 11% of 8008 women in spontaneous labor presented with tachysystole.8 This study illustrated an increased risk of cesarean section for non-reassuring fetal heart tracings and NICU admissions. The overall absolute risk was increased by only 2% or less, as 96% of women with tachysystole presented normal fetal heart monitoring. For both studies there were no individual associations between tachysystole and low Apgar score, and umbilical cord pH data were unavailable. Frey et al. conducted a case\u0026ndash;control study of 2355 women, and showed that while tachysystole was common in cases of unfavorable composite neonatal outcomes, rates of tachysystole were not significantly different compared to women with normal umbilical artery pH.22 In line with our results, Bofill et al. demonstrated, in an analysis of six randomized clinical trials involving 905 women undergoing induction or augmentation of labor, that while non-reassuring fetal heart tracings were more common in the tachysystole group, there were no adverse effects observed on Apgar scores, umbilical cord pH or NICU admissions.11 Two separate studies examining tachysystole have not shown greater incidence of low Apgar scores, umbilical artery pH or other adverse neonatal outcomes:9,10 Stewart et al,9 who examined cases in the initial 4 hours of induction of labor, and Smith et al,10 who investigated cases during the final 4 days before delivery.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eClinical debate on the issue centers on uterine contraction frequency, but perhaps examination of uterine contractile force bears more importance. Could the compression of the spiral arteries leading to reduced fetal oxygenation be a consequence, not alone of tachysystole, but also of differences in uterine contraction intensity? It is our belief that defining tachysystole only by the number of contractions per 10 minute intervals is not a reliable marker to predict adverse neonatal and maternal outcomes, as external tocodynamometers are useless in the measurement of uterine contractile force or baseline uterine tone.23 Baker et al demonstrated by using intrauterine pressure catheter\u0026nbsp; that an increased uterine activity was associated with lower umbilical cord arterial.7 In contrast, a Cochrane review found insufficient evidence for the routine use of intrauterine pressure catheter during induction of labor or augmentation with oxyctocin as it did not show an improvement in maternal and neonatal outcomes,24 with some complications reported.25 Recently, a promising non-invasive alternative technique for uterine contraction monitoring has been developed. Electrohysterography measures the uterine electrical currents through contact electrodes placed on the abdomen, and has higher sensitivity than external tocodynamometers for uterine contraction detection.26 Electrohysterography has been investigated as a tool to measure intrauterine pressure,27 and should discriminate clinical settings eg labor vs non-labor,28 prediction of preterm deliveries,29 or prostaglandins effect on uterine activity during induction of labor.30 With further study, electrohysterography monitoring could provide further insight on uterine contractions\u0026rsquo; capacity to alter placental perfusion, and thus fetal outcomes.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAmongst the strengths of our research, our patient cohort presented tachysystole at a high incidence and of relatively long duration, with these fetuses exposed to greater uterine activity than those in any comparable study. Our research was not limited to specific intrapartum periods, instead encompassing the entire labor process. Fetal heart trace analysis was performed according to current definitions of tachysystole. Our work is homogenic, using a single protocol of induction of labor in a tertiary center. Furthermore, this study is original as, contrary to some other works reporting on tachysystole, we report the tocolytic agents administered, and their impact.2,3,16,17 The major limitation of this study is its retrospective design. Retrospective chart review inhibits our capacity to control for other potential confounding factors. We have endeavored to mitigate this by dual independent analysis and correlation testing. Hidden bias may be produced by charts presenting deficient data. Our study was also limited by the fact that we were unable to retrieve the fetal heart traces of 30 (6.1%) patients.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, we illustrated that tachysystole after induction of labor by MVI is not associated to an increased rate of cesarean delivery. However, the impact of excessive uterine activity on the fetal wellbeing defined by the frequency of uterine contraction alone is probably insufficient. While prediction of neonatal outcomes according to fetal heart patterns is currently in vogue, the repercussions of uterine activity on these outcomes has largely been ignored. Further attention is required to the characterization of excessive uterine activity, and the effective application of such knowledge by the obstetrician to optimize the safety of mother and child.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eaRR\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; adjusted risk ratios\u003c/p\u003e\n\u003cp\u003eCI\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; confidence interval\u003c/p\u003e\n\u003cp\u003eNICU\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; neonatal intensive care unit\u003c/p\u003e\n\u003cp\u003eMVI\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; misoprostol vaginal inserts\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRR\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; unadjusted risk ratios\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval and consent for publication: \u003c/strong\u003eThe study was approved by the local IRB (Ethical Commission of the Canton of Vaud, Switzerland, 2018-01761), on November 21\u003csup\u003est\u003c/sup\u003e 2018. As routinely collected data was accessed, no written consent from women was obtained.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e:\u0026nbsp; The dataset used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosure of interests: \u003c/strong\u003eThe authors report no conflict of interest\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e None\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions: \u003c/strong\u003eConception and design\u003cstrong\u003e: \u003c/strong\u003eJS, DD and YV. Data collection: JS. Data analysis: JS, DD and AP. Manuscript drafting: JS. Revision of the manuscript and/or editing: YV, DB, AP, DD. All authors read and approved of the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements: \u003c/strong\u003eThe authors would like to thank Patrick Callinan for his help with the translation of the original manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e1\u0026nbsp; Martin JA, Hamilton BE, Osterman MJ, Curtin SC, Matthews TJ. Births: final data for 2013. \u003cem\u003eNatl Vital Stat Rep \u003c/em\u003e2015; 64: 1\u0026ndash;65.\u003c/p\u003e\n\u003cp\u003e2\u0026nbsp; Wing DA, Brown R, Plante LA, Miller H, Rugarn O, Powers BL. Misoprostol vaginal insert and time to vaginal delivery: a randomized controlled trial. \u003cem\u003eObstet Gynecol\u003c/em\u003e 2013; 122: 201\u0026ndash;9.\u003c/p\u003e\n\u003cp\u003e3\u0026nbsp; Bolla D, Weissleder SV, Radan A-P, \u003cem\u003eet al.\u003c/em\u003e Misoprostol vaginal insert versus misoprostol vaginal tablets for the induction of labour: a cohort study. \u003cem\u003eBMC Pregnancy Childbirth\u003c/em\u003e 2018; 18: 149.\u003c/p\u003e\n\u003cp\u003e4\u0026nbsp; Hokkila E, Kruit H, Rahkonen L, \u003cem\u003eet al.\u003c/em\u003e The efficacy of misoprostol vaginal insert compared with oral misoprostol in the induction of labor of nulliparous women: A randomized national multicenter trial. \u003cem\u003eActa Obstet Gynecol Scand\u003c/em\u003e 2019; published online Feb 16. DOI:10.1111/aogs.13580.\u003c/p\u003e\n\u003cp\u003e5\u0026nbsp; Hobson SR, Abdelmalek MZ, Farine D. Update on uterine tachysystole. \u003cem\u003eJ Perinat Med\u003c/em\u003e 2018; published online Oct 20. DOI:10.1515/jpm-2018-0175.\u003c/p\u003e\n\u003cp\u003e6\u0026nbsp; Heuser CC, Knight S, Esplin MS, \u003cem\u003eet al.\u003c/em\u003e Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings. \u003cem\u003eAm J Obstet Gynecol\u003c/em\u003e 2013; 209: 32.e1-6.\u003c/p\u003e\n\u003cp\u003e7\u0026nbsp; Bakker PC a. M, Kurver PHJ, Kuik DJ, Van Geijn HP. Elevated uterine activity increases the risk of fetal acidosis at birth. \u003cem\u003eAm J Obstet Gynecol\u003c/em\u003e 2007; 196: 313.e1-6.\u003c/p\u003e\n\u003cp\u003e8\u0026nbsp; Ahmed AI, Zhu L, Aldhaheri S, Sakr S, Minkoff H, Haberman S. Uterine tachysystole in spontaneous labor at term. \u003cem\u003eJ Matern-Fetal Neonatal Med \u003c/em\u003e2016; 29: 3335\u0026ndash;9.\u003c/p\u003e\n\u003cp\u003e9\u0026nbsp; Stewart RD, Bleich AT, Lo JY, Alexander JM, McIntire DD, Leveno KJ. Defining uterine tachysystole: how much is too much? \u003cem\u003eAm J Obstet Gynecol\u003c/em\u003e 2012; 207: 290.e1-6.\u003c/p\u003e\n\u003cp\u003e10 Smith S, Zacharias J, Lucas V, Warrick PA, Hamilton EF. Clinical associations with uterine tachysystole. \u003cem\u003eJ Matern-Fetal Neonatal Med \u003c/em\u003e2014; 27: 709\u0026ndash;13.\u003c/p\u003e\n\u003cp\u003e11 Bofill JA, Darby MM, Castillo J, Sawardecker SU, Magann EF, Morrison JC. Tachysystole Following Cervical Ripening and Induction of Labor Is Not Associated with Adverse Outcomes. \u003cem\u003eGynecol Obstet Invest\u003c/em\u003e 2017; 82: 487\u0026ndash;93.\u003c/p\u003e\n\u003cp\u003e12 Rugarn O, Tipping D, Powers B, Wing DA. Induction of labour with retrievable prostaglandin vaginal inserts: outcomes following retrieval due to an intrapartum adverse event. \u003cem\u003eBJOG \u003c/em\u003e2017; 124: 796\u0026ndash;803.\u003c/p\u003e\n\u003cp\u003e13 American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. \u003cem\u003eObstet Gynecol\u003c/em\u003e 2009; 114: 192\u0026ndash;202.\u003c/p\u003e\n\u003cp\u003e14 Macones GA, Hankins GDV, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. \u003cem\u003eObstet Gynecol \u003c/em\u003e2008; 37: 510\u0026ndash;5.\u003c/p\u003e\n\u003cp\u003e15 Fermanian J. [Measurement of agreement between 2 judges. Qualitative cases]. \u003cem\u003eRev Epidemiol Sante Publique\u003c/em\u003e 1984; 32: 140\u0026ndash;7.\u003c/p\u003e\n\u003cp\u003e16 Redling K, Schaedelin S, Huhn EA, Hoesli I. Efficacy and safety of misoprostol vaginal insert vs. oral misoprostol for induction of labor. \u003cem\u003eJ Perinat Med\u003c/em\u003e 2018; published online Sept 4. 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Initial clinical experience with a misoprostol vaginal insert in comparison with a dinoprostone insert for inducing labor. \u003cem\u003eEur J Obstet Gynecol Reprod Biol\u003c/em\u003e 2016; 200: 89\u0026ndash;93.\u003c/p\u003e\n\u003cp\u003e21 Schmidt M, Neophytou M, Hars O, Freudenberg J, K\u0026uuml;hnert M. Clinical experience with misoprostol vaginal insert for induction of labor: a prospective clinical observational study. \u003cem\u003eArch Gynecol Obstet\u003c/em\u003e 2018; published online Oct 29. DOI:10.1007/s00404-018-4942-y.\u003c/p\u003e\n\u003cp\u003e22 Frey HA, Tuuli MG, Roehl KA, Odibo AO, Macones GA, Cahill AG. Can contraction patterns predict neonatal outcomes? \u003cem\u003eJ Matern-Fetal Neonatal Med \u003c/em\u003e2014; 27: 1422\u0026ndash;7.\u003c/p\u003e\n\u003cp\u003e23 Steer PJ. Standards in fetal monitoring--practical requirements for uterine activity measurement and recording. \u003cem\u003eBJOGl\u003c/em\u003e 1993; 100 Suppl 9: 32\u0026ndash;6.\u003c/p\u003e\n\u003cp\u003e24 Bakker JJH, Janssen PF, van Halem K, \u003cem\u003eet al.\u003c/em\u003e Internal versus external tocodynamometry during induced or augmented labour. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e 2013; : CD006947.\u003c/p\u003e\n\u003cp\u003e25 Bakker PCAM, Van Rijswijk S, Van Rijsiwijk S, van Geijn HP. Uterine activity monitoring during labor. \u003cem\u003eJ Perinat Med\u003c/em\u003e 2007; 35: 468\u0026ndash;77.\u003c/p\u003e\n\u003cp\u003e26 Vlemminx MWC, Thijssen KMJ, Bajlekov GI, Dieleman JP, Van Der Hout-Van Der Jagt MB, Oei SG. Electrohysterography for uterine monitoring during term labour compared to external tocodynamometry and intra-uterine pressure catheter. \u003cem\u003eEur J Obstet Gynecol Reprod Biol\u003c/em\u003e 2017; 215: 197\u0026ndash;205.\u003c/p\u003e\n\u003cp\u003e27 Euliano T, Skowronski M, Marossero D, Shuster J, Edwards R. Prediction of intrauterine pressure waveform from transabdominal electrohysterography. \u003cem\u003eJ Matern-Fetal Neonatal Med \u003c/em\u003e2006; 19: 811\u0026ndash;6.\u003c/p\u003e\n\u003cp\u003e28 Alberola-Rubio J, Garcia-Casado J, Prats-Boluda G, \u003cem\u003eet al.\u003c/em\u003e Prediction of labor onset type: Spontaneous vs induced; role of electrohysterography? \u003cem\u003eComput Methods Programs Biomed\u003c/em\u003e 2017; 144: 127\u0026ndash;33.\u003c/p\u003e\n\u003cp\u003e29 Garcia-Casado J, Ye-Lin Y, Prats-Boluda G, Mas-Cabo J, Alberola-Rubio J, Perales A. Electrohysterography in the diagnosis of preterm birth: a review. \u003cem\u003ePhysiol Meas\u003c/em\u003e 2018; 39: 02TR01.\u003c/p\u003e\n\u003cp\u003e30 Benalcazar-Parra C, Ye-Lin Y, Garcia-Casado J, \u003cem\u003eet al.\u003c/em\u003e Electrohysterographic characterization of the uterine myoelectrical response to labor induction drugs. \u003cem\u003eMed Eng Phys\u003c/em\u003e 2018; 56: 27\u0026ndash;35.\u003c/p\u003e"},{"header":"Tables","content":"\u003cp \u003e\u003cb\u003eTable 1. Demographic and baseline characteristics of the study population \u003c/b\u003e\u003c/p\u003e\n\u003ctable \u003e\n\u003ctbody\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eTachysystole\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eYes \u003c/span\u003e\u003c/p\u003e\n\u003cp \u003en = 140\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eNo \u003c/span\u003e\u003c/p\u003e\n\u003cp \u003en = 306\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eP-value\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eMaternal age, years \u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.001\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026lt; 25\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e27 (19.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e27 (8.8)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e25-34\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e89 (63.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e189 (61.8)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026gt;= 35\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e24 (17.1)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e90 (29.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eGestational age at induction, weeks\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.06\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e37 \u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e4 (2.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e10 (3.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e38 \u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e16 (11.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e27 (8.8)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e39\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e18 (12.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e54 (17.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e40\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e19 (13.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e70 (22.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026gt; 41\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e83 (59.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e145 (47.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eNulliparity\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e98 (70.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e198 (64.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.27\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eBMI, kg/m\u003csup\u003e2\u003c/sup\u003e\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.14\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e18.5-24.9\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e12 (8.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e26 (8.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e25-29.9\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e115 (82.1)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e230 (75.2)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026gt;=30\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e13 (9.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e50 (16.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eIndication for induction\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.05\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003ePost-term pregnancy\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e50 (35.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e76 (24.8)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eRupture of membrane \u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e20 (14.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e90 (29.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eDiabetes\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e8 (5.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e21 (6.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eOligohydramnios \u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e13 (9.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e26 (8.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eFoetal movement diminution\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e3 (2.1)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e9 (2.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003ePreeclampsia/Hypertension\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e5 (3.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e14 (4.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eSuspected macrosomia\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e8 (5.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e14 (4.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eMaternal request\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e11 (7.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e21 (6.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eCholestasis of pregnancy\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e4 (2.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e3 (1.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eOther\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e18 (12.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e32 (10.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eModified Bishop\u0026rsquo;s score \u0026gt; 4\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e11 (7.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e39 (12.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.13\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eUse of tobacco during pregnancy\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e19 (13.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e46 (15.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.63\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eEpidural anesthesia\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e110 (78.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e212 (69.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.05\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eMeconium stained amniotic fluid\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e37 (26.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e63 (20.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.18\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eTocolysis\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e21 (15.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e17 (5.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.001\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp \u003eAll data shown as n (%)\u003c/span\u003e value obtained via Chi-square test of Fisher\u0026rsquo;s exact test as appropriate.\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003eBMI, body mass index\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e\u0026nbsp;\u003c/p\u003e\n\u003cp \u003e\u003cb\u003eTable 2. Adjusted risk ratio for cesarean section among patients induced with misoprostol vaginal inserts in the presence of tachysystole\u003c/b\u003e\u003c/p\u003e\n\u003ctable \u003e\n\u003ctbody\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eCaesarean\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003esection n (%)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eRR (95% CI)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eAdjusted RR (95% CI)\u003csup\u003ea\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eTachysystole\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e35 (25.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.4 (0.8-2.2)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.0 (0.7-1.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp \u003e\u003csup\u003e\u0026nbsp;a\u003c/sup\u003eAdjusted for maternal age, gestational age, indication of induction, body mass index, modified Bishop\u0026rsquo;s score \u0026gt; 4, use of epidural anesthesia, presence of meconium stained amniotic fluid by a modified Poisson regression. \u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e\u003cem\u003eRR, risk ratio; CI\u003c/em\u003e, confidence interval\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e\u0026nbsp;\u003c/p\u003e\n\u003cp \u003e\u003cb\u003eTable 3. Intrapartum monitoring, neonatal and maternal outcomes\u003c/b\u003e\u003c/p\u003e\n\u003ctable \u003e\n\u003ctbody\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Tachysystole\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003e value\u003csup\u003ea\u003c/sup\u003e\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eYes\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003eN = 140\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eNo\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003eN =306\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003cp \u003eRR (95% CI)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003eAdjusted RR (95% CI)\u003csup\u003ea\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eNRFT\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e52 (37.1)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e84 (27.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e15.9 (8.3-30.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e3.7 (3.0-4.7)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eNeonatal outcomes\u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/span\u003e\u003c/u\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eApgar \u0026lt; 7 at 5 minutes\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e7 (5.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e6 (2.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e2.6 (0.9-8.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.3 (0.8-2.2)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eCord artery pH \u0026lt; 7.10\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e14 (10.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e17 (5.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.9 (0.9-4.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e0.9 (0.6-1.3)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eNICU admission\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e18 (12.9)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e26 (8.5)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.6 (0.8-3.0)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.0 (0.7-1.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003eMaternal outcome \u003c/span\u003e\u003c/strong\u003e\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr \u003e\n\u003ctd \u003e\n\u003cp \u003ePostpartum hemorrhage \u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e31 (10.1)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e16 (11.4)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.1 (0.6-2.2)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp \u003e1.1 (0.8-1.6)\u003c/span\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd \u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp \u003eAll data shown as n (%).\u003c/span\u003e\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Tachysystole, cesarean section, cervical ripening, misoprostol vaginal inserts, neonatal outcomes, uterine activity, uterine contractions ","lastPublishedDoi":"10.21203/rs.2.11582/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.2.11582/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Background\nIn western countries, induction of labor is a common obstetrical intervention. Uterine tachysystole frequently manifests after cervical ripening by misoprostol vaginal inserts. Currently, there is insufficient evidence regarding the clinical impact of tachysystole during induction of labor. Therefore, the objective of the current study is to examine if tachysystole is associated with an increased risk of cesarean section following induction of labor by misoprostol vaginal inserts.\n\nMethods\nWe conducted a retrospective cohort study of 446 women over 37 weeks of gestation admitted for labor induction by misoprostol vaginal inserts between May 2016 and May 2017. Fetal heart rate and uterine activity tracings were assessed for tachysystole, defined as ≥ 6 contractions per 10 minutes, averaged over a 30-minute window. Univariate analysis was performed by using t-test and Chi-square, comparing demographics, pregnancy characteristics, intrapartum monitoring, mode of delivery, neonatal outcomes (Apgar score \u003c 7 at 5 minutes, umbilical cord artery pH \u003c 7.10, neonatal intensive care unit admission) and maternal outcomes, with regard to the presence of tachysystole. The association between tachysystole and cesarean section was evaluated after adjusting for potential confounders by a modified Poisson regression model, expressed as an adjusted risk ratio and 95% confidence intervals.\n\nResults\nA total of 140 women (31.4%) presented with tachysystole. The median duration of tachysystole was 2 hours 12 minutes. The rate of cesarean section was 25.0% (N=35) among patients with tachysystole and 19.6% (N=60) for those without tachysystole. Presence of tachysystole during induction of labor with misoprostol vaginal inserts was not associated with cesarean section (adjusted risk ratio,1.0; 95% confidence interval, 0.7 to 1.4). Neonatal and maternal outcomes were similar between mothers who did and did not experience tachysystole.\n\nConclusions\nThis study illustrates that tachysystole is not associated with an increased risk of cesarean section after induction of labor by misoprostol vaginal inserts. The impact of excessive uterine activity on the fetal wellbeing defined by the frequency of uterine contraction alone is probably insufficient. Further research on the development of accurate measures of uterine contractility is necessary to better understand its effect on fetal well-being.","manuscriptTitle":"Tachysystole and risk of cesarean section after labor induction using misoprostol: a cohort study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2019-07-17 20:06:38","doi":"10.21203/rs.2.11582/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"22b65e79-1dbc-4ace-b0a9-60f9d55a3037","owner":[],"postedDate":"July 17th, 2019","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":17037,"name":"Maternal \u0026 Fetal Medicine"}],"tags":[],"updatedAt":"2021-01-25T19:48:23+00:00","versionOfRecord":{"articleIdentity":"rs-2432","link":"https://doi.org/10.1016/j.ejogrb.2020.04.026","journal":{"identity":"european-journal-of-obstetrics-and-gynecology-and-reproductive-biology","isVorOnly":true,"title":"European Journal of Obstetrics \u0026 Gynecology and Reproductive Biology"},"publishedOn":"2020-06-01 13:00:00","publishedOnDateReadable":"June 1st, 2020"},"versionCreatedAt":"2019-07-17 20:06:38","video":"","vorDoi":"10.1016/j.ejogrb.2020.04.026","vorDoiUrl":"https://doi.org/10.1016/j.ejogrb.2020.04.026","workflowStages":[]},"version":"v1","identity":"rs-2432","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"identity":"rs-2432","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}