The duration of labor in primiparas undergoing vaginal birth after cesarean delivery

The purpose of this retrospective investigation was to evaluate the duration of labor in women having a trial of labor after a previous low transverse cervical cesarean delivery for dystocia. We specifically sought to determine whether these patients experienced a labor similar to that of the nulliparous or multiparous woman. During the study period, 73 women who had previously undergone a cesarean for dystocia had a successful trial of labor. We matched each study patient to two controls. One control was nulliparous and the second was a woman who had undergone a previous uncomplicated vaginal delivery. Thirty-six study patients had had a cesarean in the latent phase of labor (group I), 29 in the active phase of labor (group II), and eight in the second stage of labor (group III). With the exception of group I patients, the first and second stages of labor were similar to those of nulliparous control patients. Patients in group I had a significantly longer first stage of labor than did the nulliparous controls. There was no significant difference in oxytocin requirements among the three groups. We conclude that primiparous women who have had a previous cesarean delivery for dystocia have a duration of labor similar in length or longer than that of nulliparous women.     

The effect of continuous epidural analgesia on cesarean section for dystocia in nulliparous women

Epidural analgesia in labor is generally accepted as safe and effective and therefore has become increasingly popular. However, little is known regarding the effect of epidural analgesia on the incidence of cesarean section for dystocia in nulliparous women. During the first 6 months of 1987 we studied 711 consecutive nulliparous women at term, with cephalic fetal presentations and spontaneous onset of labor. Comparison of 447 patients who received epidural analgesia in labor with 264 patients who received either narcotics or no analgesia was performed. The incidence of cesarean section for dystocia was significantly greater (p less than 0.005) in the epidural group (10.3%) than in the nonepidural group (3.8%). There remained a significantly increased incidence (p less than 0.005) of cesarean section for dystocia in the epidural group after selection bias was corrected and the following confounding variables were controlled by multivariate analysis: maternal age, race, gestational age, cervical dilatation on admission, use of oxytocin, duration of oxytocin use, maximum infusion rate of oxytocin, duration of labor, presence of meconium, and birth weight. The incidence of cesarean section for fetal distress was similar (p greater than 0.20) in both groups. There were no clinically significant differences in frequency of low Apgar scores at 5 minutes or cord arterial and venous blood gas parameters between the two groups. This study suggests that epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparous women.     

Active management of labor: is it suitable for a developing country?

OBJECTIVE: To evaluate the effectiveness of active management of labor in the setting of a developing country. METHODS: This historical cohort study compared the labor characteristics and outcome of all anti-HIV positive nulliparous pregnant women (n=96), who delivered between January 1991 and March 1999, treated with traditional labor management to all anti-HIV negative nulliparous pregnant women (n=1856), who delivered in 1998, treated with active management of labor in the tertiary center of a developing country. The year 1998 was chosen by using the total cesarean section rate of nulliparous patients from 1991 to 1998 to find the mean, then selected the year with cesarean section rate nearest to the mean as a control. Data were analyzed by the chi-square and t-tests. RESULTS: The length of labor was significantly shortened in the active management group (6.3+/-3.3 h vs. 8.9+/-6 h, P<0.001). A significantly greater proportion of the traditional management group had prolonged labor (29.3% vs. 4.9%, P<0.001). However, the cesarean section rate was not different between the two groups (active vs. traditional=17% vs. 14.6%, P=0.7) with dystocia as a major indication in both groups. Maternal and fetal complications were not different. CONCLUSION: The active management of labor shortened the duration of labor and reduced prolonged labor; however, it did not decrease the cesarean section rate.     

The continuing effectiveness of active management of first labor, despite a doubling in overall nulliparous cesarean delivery

OBJECTIVE: The purpose of this study was to determine the continuing effectiveness of active management of labor, a protocol that involves early detection and correction of dystocia with oxytocin in spontaneous cephalic nulliparous labor, by analysis of the contribution of this cohort to a doubled overall nulliparous cesarean delivery rate. STUDY DESIGN: This was a retrospective analysis of annually collated institutional data on cesarean delivery and perinatal outcome. RESULTS: From 1989 to 2000, 81,855 women were delivered at the National Maternity Hospital, of whom 34,201 women (42%) were nulliparous; the annual proportion of nulliparous women in spontaneous labor decreased progressively from 83% to 60%; the overall nulliparous cesarean rate increased from 8.1% to 16.6%. Cesarean birth rate among nulliparous women in spontaneous labor, although showing a significant upward trend between 1989 and 2000 (2.4%-4.8%; P = .001), was stable, averaging 5% for the last 8 years (P = .705); the peripartum death rate in this group fell significantly (P = .024). Comparing results for 1989 with results for 2000, nulliparous women in spontaneous labor accounted for 14% of the overall increase in cesarean deliveries (dystocia, 5%), compared with 51% for nulliparous women with induced labor. The perinatal mortality rate in term infants was unchanged. CONCLUSION: Active management of spontaneous first labors remains an effective protocol for the promotion of vaginal delivery with low peripartum mortality rates; factors other than dystocia in spontaneous labor account for the progressive increase in the nulliparous cesarean delivery rate.     

Is abnormal labor associated with shoulder dystocia in nulliparous women?

OBJECTIVE: This study was undertaken to examine the relationship between labor abnormalities and shoulder dystocia in nulliparous women. STUDY DESIGN: Nulliparous women whose delivery was complicated by shoulder dystocia were studied and compared with a control group selected based on the best possible match for race, labor type (spontaneous or induced), and birth weight. The duration of first and second stage of labor, as well as the rates of labor progress, were calculated and compared between groups. RESULTS: During this 4-year study period, there were 8010 nulliparous singleton deliveries of which 65 (0.8%) were complicated by shoulder dystocia. Compared with controls, there was no difference in the rate of cervical dilation in the active phase of the first stage of labor. In the shoulder dystocia group, more patients had a second stage of labor greater than 2 hours (22% vs 3%; P <.05) and had operative vaginal deliveries (26% vs 1.5%; P <.001). In shoulder dystocia cases with birth weight greater than 4000 g, 33% had a second stage of labor greater than 2 hours. CONCLUSION: In our population, the combination of fetal macrosomia, second stage of labor longer than 2 hours and the use of operative vaginal delivery were associated with shoulder dystocia in nulliparous women.     

Impact of early admission in labor on method of delivery.

OBJECTIVE: The effect of the timing of admission in labor unit on the method of delivery was evaluated in a cohort study. METHOD: Four hundred and sixty six low-risk nulliparous women who were admitted in the labor unit in latent phase (group 1) were compared with 329 parturient women who were admitted in the active phase (group 2) to determine rate of and reasons for cesarean section, cervical dilation at the time of cesarean, and the rate of labor augmentation. RESULT: The number of cesarean deliveries in group 1 was greater than that in the group 2 (301 vs 80, p<0.0001 ). The main reason for cesarean section in group 1 was dystocia, and in 2, fetal distress. The rate of cesarean section in the women who were augmented was greater in group 1 than in group 2 (54% vs 23%, p<0.0001). CONCLUSION: Later admission in labor increases the rate of spontaneous vaginal delivery in low risk nulliparous women.     

Amniotomy and oxytocin treatment of functional dystocia and route of delivery

The details of clinical management were examined in 101 nulliparous patients with functional dystocia who underwent amniotomy and were treated with oxytocin in the first stage of labor. It was our hypothesis that if the alleged "high" rate of cesarean sections was the result of mediocre or flawed practices, these should be most evident in patients delivered abdominally. A group of 68 patients delivered vaginally are compared with 33 patients delivered by cesarean section. The means of many variables were statistically similar. The cesarean group was characterized by less cervical dilatation at admission, greater birth weights, larger maximum doses of oxytocin, and longer durations of oxytocin therapy. We conclude from our analysis that the decision to perform cesarean section in nulliparous women with functional dystocia arises from disabilities of the patient and not from differences in the application of our management principles, services, or treatments.     

Effects of Epidural Analgesia: Some Questions and Answers

ABSTRACT: The effects of epidural analgesia on first labors have been studied by Thorp and colleagues (1,2). One study has been published (3) and is the subject of a question-and-answer discussion, presented here. In this study 711 consecutive nulliparous women at term, with spontaneous onset of labor and cephalic presentation, were divided into one group (n = 447) who received epidural analgesia in labor and another group (n = 264) who received narcotics or no analgesia. The frequency of cesarean section for dystocia was significantly greater (p < 0.005) in the epidural group (10.3%) than in the nonepidural group (3.8%), even after selection bias was corrected and the variables of maternal age and race; gestational age; cervical dilatation on admission; use, duration, and maximum infusion rate of oxytocin; labor duration; presence of meconium; and birth weight were controlled. For both groups the frequency of cesarean section for fetal distress was similar (p < 0.20), and the frequency of low Apgar scores at 5 minutes and cord blood gas values showed no significant differences. The authors concluded that “epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparous women’(3).     

Spontaneous rupture of the membranes, functional dystocia, oxytocin treatment, and the route of delivery

The details of clinical management were examined in 96 nulliparous patients with functional dystocia who had spontaneous rupture of the membranes before admission and were treated with oxytocin in the first stage of labor. It was our hypothesis that if the allegedly "high" rate of cesarean sections was the result of mediocre or flawed practices, these should be most evident in patients delivered abdominally. A group of 59 patients delivered vaginally were compared with 37 patients delivered by cesarean section. The means of many variables were not statistically different. The cesarean section group was characterized by smaller stature, a lesser cervical dilatation rate both before and after oxytocin administration, a larger maximum oxytocin dose, a longer period of oxytocin administration, more frequent cessation of oxytocin administration or dose reduction because of hypercontractility or an abnormal fetal heart rate or both, and a higher incidence of intra-amniotic infection. We conclude that the decision to perform cesarean section in nulliparous women with functional dystocia arises from disabilities of the patient and not from differences in the application of our management principles, services, or treatments.     

Should we allow a trial of labor after a previous cesarean for dystocia in the second stage of labor?

OBJECTIVE: To estimate the rate of successful vaginal birth including operative vaginal delivery in patients with a previous cesarean for cephalopelvic disproportion in the second stage of labor. METHODS: Data from all patients who underwent trial of labor after a previous cesarean between 1990 and 2000 at our tertiary care institution were analyzed. Medical records were reviewed and data collected for the following variables: indication for the previous cesarean, birth weight and cervical dilatation at previous cesarean delivery, as well as the mode of delivery (spontaneous, vacuum, forceps, cesarean) and the birth weight for the subsequent pregnancy. Pearson's chi(2) test and one-way analysis of variance were used for statistical analyses. RESULTS: There were 2002 patients included in the study. Two hundred fourteen (11%) had their previous cesarean for dystocia in the second stage of labor, 654 (33%) for dystocia in the first stage of labor, and 1134 (57%) for other indications. The vaginal birth after cesarean success rate was 75.2% (P = .015 vs other indications), 65.6% (P < .001 vs other indications), and 82.5%, respectively. The rate of operative vaginal delivery was 15%, 12%, and 10% (P = .109). CONCLUSION: A trial of labor is reasonable in women whose previous cesarean was for dystocia in the second stage of labor. In this series, patients who underwent a trial of labor after a previous cesarean for dystocia in the second stage had 75.2% (95% confidence interval 69.5, 81.0) chance of achieving vaginal delivery.     

Dystocia in nulliparous patients monitored with fetal pulse oximetry

OBJECTIVE: A critical analysis of the United States randomized controlled trial of fetal pulse oximetry concluded that nonreassuring fetal heart rate patterns used for study entry may have been a marker for dystocia. We prospectively studied nulliparous women in labor whose progress was monitored with fetal pulse oximetry to examine the relationship between nonreassuring fetal heart rate patterns and operative delivery for dystocia. STUDY DESIGN: A prospective nonrandomized observational cohort study compared two distinct classes of nonreassuring fetal heart rate patterns (class I: intermittent, mildly nonreassuring; class II: persistent, progressive, and moderate to severely nonreassuring) among nulliparous patients with the use of fetal pulse oximetry to confirm fetal well-being. Definitions of dystocia included the cessation of labor progress in the first (3 hours) or second (2 hours) stage of labor, despite adequate uterine activity that was assessed with an intrauterine pressure catheter. Independent review confirmed the classification of nonreassuring fetal heart rate patterns and study entry criteria. RESULTS: Two hundred seventy-four patients met study criteria and had sufficient information for fetal heart rate tracing interpretation. Two hundred thirty-seven patients (86.5%) were class II, and 37 patients (13.5%) were class I. The two classes of patients were comparable in a variety of obstetric, demographic, and perinatal variables. Twelve percent of all patients were delivered for nonreassuring fetal status. Significantly more class II patients (22%) were delivered by cesarean for dystocia than were class I patients (8%). Higher doses and a longer number of hours of oxytocin were required among class II patients. Significantly more occiput posterior positions were noted among all patients who underwent cesarean delivery for dystocia compared with other modes of delivery. CONCLUSION: Significantly nonreassuring fetal heart rate patterns predict cesarean delivery for dystocia among nulliparous patients with normally oxygenated fetuses in a setting of a standardized labor management protocol. This confirms the observations in the randomized controlled trial of fetal pulse oximetry in the United States and may provide insight into the treatment of nonprogressive labor in contemporary practice.     

Bishop score and risk of cesarean delivery after induction of labor in nulliparous women

OBJECTIVE: To quantify the risk and risk factors for cesarean delivery associated with medical and elective induction of labor in nulliparous women. METHODS: A prospective cohort study was performed in nulliparous women at term with vertex singleton gestations who had labor induced at 2 obstetrical centers. Medical and elective indications and Bishop scores were recorded before labor induction. Obstetric and neonatal data were analyzed and compared with the results in women with a spontaneous onset of labor. Data were analyzed using univariate and multivariable regression modeling. RESULTS: A total of 1,389 women were included in the study. The cesarean delivery rate was 12.0% in women with a spontaneous onset of labor (n = 765), 23.4% in women undergoing labor induction for medical reasons (n = 435) (unadjusted odds ratio [OR] 2.24; 95% confidence interval [CI] 1.64-3.06), and 23.8% in women whose labor was electively induced (n = 189) (unadjusted OR 2.29; 95% CI 1.53-3.41). However, after adjusting for the Bishop score at admission, no significant differences in cesarean delivery rates were found among the 3 groups. A Bishop score of 5 or less was a predominant risk factor for a cesarean delivery in all 3 groups (adjusted OR 2.32; 95% CI 1.66-3.25). Other variables with significantly increased risk for cesarean delivery included maternal age of 30 years or older, body mass index of 31 or higher, use of epidural analgesia during the first stage of labor, and birth weight of 3,500 g or higher. In both induction groups, more newborns required neonatal care, more mothers needed a blood transfusion, and the maternal hospital stay was longer. CONCLUSION: Compared with spontaneous onset of labor, medical and elective induction of labor in nulliparous women at term with a single fetus in cephalic presentation is associated with an increased risk of cesarean delivery, predominantly related to an unfavorable Bishop score at admission. LEVEL OF EVIDENCE: II-2.     

A review of factors associated with dystocia and cesarean section in nulliparous women

The primary indication for cesarean section in nulliparous women continues to be clinical diagnoses that fall under the rubric of dystocia. These diagnoses account for approximately two-thirds of all cesareans experienced by otherwise healthy nulliparous women. Contemporary research evidence suggests that this clinical phenomenon is complex and multifactorial. This review explores factors associated with the phenomenon of dystocia in the context of a conceptual model that considers women's physical and psychological characteristics, fetal factors, intrapartum care and interventions, assessments and clinical decision-making of health care providers, the sociopolitical environment, and the social and physical environment of childbirth. Clinical recommendations include emphasis on the maintenance of normal weight and weight gain during pregnancy, delaying the admission of nulliparous women to the hospital until active labor is established, avoiding elective induction for nulliparous women, keeping women well-hydrated and well-fed during labor, providing high-quality supportive care during labor, staying the course with effective treatment when dystocia is encountered, and a renewed emphasis on the psychobehavioral preparation of nulliparous women for the realities of labor.     

Does epidural analgesia prolong labor and increase risk of cesarean delivery? A natural experiment

OBJECTIVE: More than 50% of pregnant women in the United States are using epidural analgesia for labor pain. However, whether epidural analgesia prolongs labor and increases the risk of cesarean delivery remains controversial. STUDY DESIGN: We examined this question in a community-based, tertiary military medical center where the rate of continuous epidural analgesia in labor increased from 1% to 84% in a 1-year period while other conditions remained unchanged-a natural experiment. We systematically selected 507 and 581 singleton, nulliparous, term pregnancies with spontaneous onset of labor and vertex presentation from the respective times before and after the times that epidural analgesia was available on request during labor. We compared duration of labor, rate of cesarean delivery, instrumental delivery, and oxytocin use between these two groups. RESULTS: Despite a rapid and dramatic increase in epidural analgesia during labor (from 1% to 84% in 1 year), rates of cesarean delivery overall and for dystocia remained the same (for overall cesarean delivery: adjusted relative risk, 0.8; 95% confidence interval, 0.6-1.2; for dystocia: adjusted relative risk, 1.0; 95% confidence interval, 0.7-1.6). Overall instrumental delivery did not increase (adjusted relative risk, 1.0; 95% confidence interval, 0.8-1.4), nor did the duration of the first stage and the active phase of labor (multivariate analysis; P >.1). However, the second stage of labor was significantly longer by about 25 minutes (P <.001). CONCLUSION: Epidural analgesia during labor does not increase the risk of cesarean delivery, nor does it necessarily increase oxytocin use or instrumental delivery caused by dystocia. The duration of the active phase of labor appears unchanged, but the second stage of labor is likely prolonged. (Am J Obstet Gynecol 2001;185:128-34).     

Outcome after elective labor induction in nulliparous women: a matched cohort study

OBJECTIVE: To determine whether elective induction of labor in nulliparous women is associated with changes in fetomaternal outcome when compared with labor of spontaneous onset.Study Design: All 80 labor wards in Flanders (Northern Belgium) comprised a matched cohort study. From 1996 through 1997, 7683 women with elective induced labor and 7683 women with spontaneous labor were selected according to the following criteria: nulliparity, singleton pregnancy, cephalic presentation, gestational age at the time of delivery of 266 to 287 days, and birth weight between 3000 and 4000 g. Each woman with induced labor and the corresponding woman with spontaneous labor came from the same labor ward, and they had babies of the same sex. Both groups were compared with respect to the incidence of cesarean delivery or instrument delivery and the incidence of transfer to the neonatal ward. RESULTS: Cesarean delivery (9.9% vs 6.5%), instrumental delivery (31.6% vs 29.1%), epidural analgesia (80% vs 58%), and transfer of the baby to the neonatal ward (10.7% vs 9.4%) were significantly more common (P <.01) when labor was induced electively. The difference in cesarean delivery was due to significantly more first-stage dystocia in the induced group. The difference in neonatal admission could be attributed to a higher admission rate for maternal convenience when the women had a cesarean delivery. CONCLUSION: When compared with labor of spontaneous onset, elective labor induction in nulliparous women is associated with significantly more operative deliveries. Nulliparous women should be informed about this before they submit to elective induction.     

Potential Impact of Guidelines for the Prevention of Cesarean Deliveries in a Contemporary Canadian Population

ObjectiveThis study sought to describe how the implementation of recent labour guidelines may affect the cesarean delivery rate in a population in Alberta.MethodsThis retrospective study was conducted on primiparous women who were in labour with singleton term fetuses with cephalic presentation in Alberta from 2007 to 2016 (n = 181 738), and it used data from a perinatal database. Modelled cesarean delivery rates were calculated to determine the potential impact of the recent guidelines on the cesarean delivery rate by using the percentage of cesarean deliveries that occurred outside the threshold of the recent labour guidelines.ResultsA total of 21.7% of the cesarean deliveries for dystocia occurred outside of the guidelines related to the first stage of labour arrest for spontaneous labour (n = 9282), and 45.4% occurred outside of the guidelines related to the first stage of labour arrest for induced labours (n = 11 712). A total of 69.0% of the cesarean deliveries for dystocia occurred outside of the failed induction of labour guidelines (n = 4921), and 55.4% occurred outside of the second stage labour arrest guidelines (n = 6632). Assuming that the labour arrest guidelines are effective at reducing the cesarean delivery rate 25% of the time, the cesarean delivery rate for primiparous women in labour would be reduced from 22.5% to 20.7%. Assuming a 75% adherence/effectiveness rate, the cesarean delivery rate would be reduced to 17.1%.ConclusionThe recent labour guidelines have the potential to have a substantial impact on the intrapartum cesarean delivery rate in primiparous women with singleton fetuses with cephalic presentation at term if the guidelines are put into practice.     

Dystocia correlates with body mass index in both spontaneous and induced nulliparous labors

Objective.?To assess the influence of body mass index (BMI) on labor outcome in both induced and actively managed spontaneous nulliparous labors.

Methods.?This is a prospective observational study of all consecutive nulliparous women who delivered in the National Maternity Hospital, Dublin in 2008. Labor outcome variables examined in relation to BMI included duration of labor, oxytocin requirements, epidural use, mode of delivery, and infant birthweight.

Results.?Of 4162 nulliparous women who labored during the study period, accurate BMI data were available on 3158, who constituted the study group. Of these women, 2143 (68%) were in spontaneous labor and 1015 (32%) had labor induced. A statistically significant association was found between maternal BMI at first antenatal visit and the need for intrapartum cesarean section (CS) in both spontaneous and induced labors (p?<?0.05). A significantly poorer response to oxytocin augmentation was observed in women with a higher BMI, as indicated by an increased intrapartum CS rate for dystocia despite oxytocin augmentation. There was a linear relationship between maternal BMI and gestational age at onset of spontaneous labor.

Conclusion.?Our results in a large consecutive series of nulliparous labors confirm the potent influence of increasing maternal BMI on intrapartum events.     

Epidural analgesia and cesarean section for dystocia: risk factors in nulliparas.

A retrospective study assessing the effect of epidural analgesia in labor on the incidence of cesarean section was performed. The first 500 consecutive nulliparas meeting the following criteria were included in this study: term (37 weeks or longer) and singleton gestation, cephalic presentation, spontaneous onset of labor, and 5 cm or less of cervical dilation on admission. Patients were grouped according to their rate of cervical dilation in early labor (greater than or equal to 1 cm/hr, and less than 1 cm/hr) and the timing of epidural placement (none, early, or late). There was no effect of epidural analgesia on the incidence of cesarean section for fetal distress. The incidence of cesarean section for dystocia was significantly greater (p greater than 0.000001) in the epidural group (15.6%) than in the nonepidural group (2.4%). The greatest effect of epidural analgesia on the incidence of cesarean section for dystocia was observed in nulliparas who dilated at slower rates (less than 1 cm/hr) in early labor and who had epidural analgesia placed at 5 cm or less of cervical dilation (20.6% versus 3.4%, relative risk of 6, p less than 0.0005). The increase of cesarean section for dystocia associated with epidural analgesia could not be accounted for when other possibly confounding variables were studied. Both the dilation rate prior to epidural placement and the cervical dilation at epidural placement were significantly correlated to frequency of cesarean section for dystocia (p less than 0.01). This study suggests that epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparas.     

Indicated labor induction with vaginal prostaglandin E2 increases the risk of cesarean section even in multiparous women with no previous cesarean section

AIMS: To evaluate the impact of induction of labor with vaginal tablets of prostaglandin E2 on the rate of cesarean section (CS), and to identify possible predictors of successful vaginal delivery. METHODS: 1541 consecutive women admitted for induction of labor with vaginal tablets of PGE2 were retrospectively compared with 574 consecutive women with spontaneous onset of labor. RESULTS: Maternal age, nulliparity, previous CS, gestational age, and birth weight were similar in the study and control groups. The CS rate was twofold higher in the study group (20.7% vs 10.6%). CS rates in the study and control groups were 26.9% and 12.8% for the nulliparous women, and 11.2% and 5.1% for the multiparous women with no previous CS. Neither group had major maternal or fetal complications. A logistic regression model and stepwise analysis showed that nulliparity, previous CS, maternal age, number of PGE2 applications, birth weight, and the induction of labor by itself were independent significant risk factors for increased CS rate. CONCLUSIONS: Induction of labor with vaginal PGE2 tablets results in a vaginal delivery rate of 79.3%, with apparently no serious maternal or fetal complications. Nulliparity, and previous CS are the most significant risk factors for increased CS rate. However, even after these risk factors are excluded and controlling for possible predictors for CS, PGE2 induction is independently associated with a twofold increase in CS rate, most often because of labor dystocia.     

早期常规人工破膜对产程及胎儿与新生儿影响的Meta分析

目的探讨产程中早期常规人工破膜对产程及胎儿或新生儿的影响。方法对“早期人工破膜可增加胎儿心率异常的发生、早期人工破膜的随机化对照试验、早期人工破膜对初产妇发生难产危险的影响、选择性人工破膜对胎心率及产程影响的随机研究、比较早期人工破膜与选择性人工破膜对正常产程影响的临床随机研究和关于产程中主动管理的临床随机研究和Meta分析等6篇文献中的临床随机对照试验结果,使用固定效应模型方法进行Meta分析。结果（1）早期常规人工破膜能够缩短第一产程95min,95％可信区间（CI）为-119．17～-70．52。（2）没有足够证据表明早期常规人工破膜能够对分娩方式产生影响：剖宫产率OR=1．25,95％CI为0．99～1．57,器械阴道助产率OR=1．05,95％CI为0．90～1．24。（3）早期常规人工破膜对第一产程胎心率异常的发生没有影响（OR=0．95,95％CI为0．75～1．21）,但增加第二产程胎心率异常的发生（OR=1．28,95％CI为1．02～1．61）。（4）没有足够证据表明早期常规人工破膜能够对羊水胎粪污染的发生产生影响（OR=1．17,95％CI为0．78～1．73）,但可能降低新生儿1分钟Apgar评分〈7分的发生率（OR=0．71,95％CI为0．49～1．03）。结论常规早期人工破膜可缩短产程,并可能减少新生儿1分钟Apgar评分〈7分的发生;但增加第二产程胎心率异常的发生以及有可能会增加剖宫产率。