Use of mifepristone to ripen the cervix and induce labor in term pregnancies

OBJECTIVE: This study was undertaken to determine the efficacy of mifepristone for ripening the cervix and inducing labor in term pregnancies. STUDY DESIGN: In a double-blind placebo-controlled dose-finding study, 346 women received 50, 100, 200, 400, or 600 mg of mifepristone or placebo. The main endpoint for efficacy was the number of patients in whom labor occurred between 12 and 45 and 54 hours after treatment or who had a Bishop score 6 or greater. Maternal and fetal tolerability was also studied. RESULTS: No significant efficacy was observed whatever the dose of mifepristone. Mifepristone was well tolerated by the mother and fetus. CONCLUSION: Mifepristone, at doses up to 600 mg, does not induce labor within 54 hours in patients with unfavourable cervical status.     

Mifepristone for preinduction cervical ripening beyond 41 weeks' gestation: a randomized controlled trial

OBJECTIVE: To compare the effect of mifepristone with placebo on cervical ripening before labor induction in prolonged pregnancies. METHODS: One hundred eighty women with pregnancies beyond 41 weeks and undilated, uneffaced cervices were assigned randomly to receive mifepristone 200 mg or placebo and observed for 24 hours. We then gave intravaginal misoprostol 25 microg every 4 hours or intravenous oxytocin. We expected 60% of placebo-treated and 80% of mifepristone-treated women to deliver vaginally within 48 hours. RESULTS: Among 180 subjects, 97 received mifepristone and 83 received placebo. The mean interval (+/- standard deviation [SD]) from start of induction to delivery was 2209 +/- 698 minutes for mifepristone-treated subjects and 2671 +/- 884 minutes for placebo-treated subjects (P <.001, log-transformed data). Twelve (13. 6%) mifepristone-treated women and seven (10.8%) placebo-treated women delivered vaginally on day 1 (P =.60). After 24 hours, the median Bishop score for both groups was 3 (0-11) (P =.51). One hundred thirty-one subjects required misoprostol, 65 (67.0%) were mifepristone-treated women, and 66 (79.5%) placebo-treated women (P =.06). The median (range) oxytocin dose was 871.5 (0-22,174) mU for mifepristone-treated women and 2021.0 (0-24,750) mU for placebo-treated women (P =.02). Seventy-seven (87.5%) mifepristone-treated women and 46 (70.8%) placebo-treated women delivered vaginally 48 hours after the start of treatment (P =.01). There were nine cesareans in the mifepristone group and 18 in the placebo group (P =.02). More nonreassuring fetal heart rate patterns and uterine contractile abnormalities occurred in mifepristone-treated subjects. There were no statistically significant differences in neonatal outcomes between groups. CONCLUSION: Mifepristone had a modest effect on cervical ripening when given 24 hours before labor induction, appearing to reduce the need for misoprostol and oxytocin compared with placebo.     

Bishop score and the outcome of labor induction with misoprostol

BACKGROUND: The aim of the study was to retrospectively identify possible factors for predicting the outcome of induction with misoprostol. METHODS: Fifty micrograms of misoprostol were administered intravaginally every 6 h during the first 2 days of induction, up to a maximum of 4 doses. The Bishop score, indication for induction, gestational length, maternal age, and parity were analyzed. The study involved 99 patients (47 primiparous and 52 multiparous) at term (>36 weeks of gestation) with unripe cervices. RESULTS: Forty-five per cent of the patients achieved ripening of cervix and went into labor after a single dose of misoprostol; a further 45% required 2 doses. Nine patients received more than 2 tablets. Ninety-seven per cent of all vaginal deliveries occurred within the first 2 days of induction. Ninety-five per cent of the patients delivered vaginally when the Bishop score was >3, compared with 75% of those with a Bishop score of < or =3 (p=0.003). Among factors creating the Bishop scoring system, in logistic regression analysis effacement of the cervix was the only independent, significant predictor of cesarean section (p=0.003, OR = 0.16) even after adjusting for maternal age, which also was a significant predictor in the regression analysis. Eleven patients had previously had a cesarean section; one of them had a uterine rupture with a fatal outcome for the fetus. All women with a previously scarred uterus are now excluded from misoprostol treatment. CONCLUSION: Misoprostol 50 microg administered intravaginally every 6 h according to this protocol is highly effective for inducing labor in carefully selected patients with unripe cervices.     

Mifepristone and misoprostol in the induction of labor at term.

OBJECTIVE: To assess the ability of mifepristone to prime the cervix adequately and induce labor in pregnant women at term; and when mifepristone alone proves insufficient, to determine whether oral misoprostol taken 48 h following mifepristone administration is effective in inducing labor. METHODS: In this prospective study 50 pregnant women at term with an unfavorable cervix were given 400 mg of mifepristone orally and allowed to return home. If labor did not start within 48 h, the women were admitted and induction was continued with 50 mug of misoprostol, a prostaglandin (PG) E1 analogue, taken orally every 4 h. The 50 controls, who were matched prospectively for parity and pregnancy duration, underwent labor induction according to the routine administration of 3-mg tablets of PGE2 vaginally. RESULTS: In the study group, 66% of the women entered labor spontaneously or had a sufficiently ripened cervix within 48 h of taking mifepristone. However, there was no difference in time between prostaglandin administration and delivery between the control group and the 34% of women who required misoprostol in the study group. In the study group, the cesarean section rate was significantly lower among the women whose labor was induced with mifepristone alone than among those who required misoprostol. There were no differences overall in obstetric or neonatal outcomes between the study and control groups. CONCLUSIONS: In this pilot sample, 400 mg of mifepristone was effective in inducing cervical changes and labor. Although there were no adverse effects using oral misoprostol in combination with mifepristone, labor was more difficult to induce in the women who did not respond to mifepristone alone, and these women had a higher operative delivery rate.     

缓释型前列腺素E2栓用于足月妊娠引产的临床观察

目的 :研究缓释型前列腺素E2 栓用于足月妊娠引产的有效性及安全性。方法 :随机单盲安慰剂对照研究。选择 2 0例 2 5～ 34岁单胎足月无引产禁忌证产妇 ,随机分为用药组 (10人 )和安慰剂组 (10人 )。记录宫颈Bishop评分、用药至临产时间、2 4小时引产成功率、经阴道分娩率、新生儿Apgar评分和产后出血量等。结果 :用药组 4小时宫颈成熟 ,用药至临产平均 8小时 5 5分钟 ,引产成功 9例 ,经阴道分娩率 7例 ,新生儿Apgar评分 1分钟全部 10分 ,产后出血量平均15 5ml;安慰剂组宫颈无变化 ,引产全部失败。结论 :首次于国内通过小样本临床观察后 ,认为缓释型前列腺素E2 栓用于足月引产效果好 ,副反应小 ,使用方便而安全     

Nonpharmaceutical ripening of the unfavorable cervix and induction of labor by a novel double balloon device

Artificial ripening of the unfavorable cervix was attempted in 48 women using intracervical prostaglandin (PG) E2 gel applied by a cannula and in 70 others by a newly designed double balloon device (Atad Ripener Device). In the first group (phase A), application of PGE2 gel by intracervical cannula resulted in a mean increase of 3 points in the Bishop score and a mean instillation-to-delivery time of 34.2 hours. The study of labor induction by the double balloon device was carried out in two parts. One (phase B) consisted of a double-blind randomized controlled study in which, through the double balloon device, ten women received PGE2 gel and another ten were given placebo gel. There was no significant difference in the increase of Bishop score between the two groups (5.8 points in the treatment group and 6.0 in the placebo-controlled group). Ninety percent of women in both groups delivered vaginally with a mean of 20.8 hours after device insertion. The third phase of the study consisted of an open trial of inserting the double balloon device alone without PGE2, and inflating the balloons in 50 patients. A mean increase of 4.4 points in the Bishop score was noted in these women. These findings suggest that the use of the double balloon device for ripening of the unfavorable cervix is an effective and well-tolerated method of labor induction.     

Elective induction of labor: failure to follow guidelines and risk of cesarean delivery

BACKGROUND: Estimate the frequency of failure to follow the French consensus guidelines for elective induction, and assess how failure affects the rate of cesarean delivery. METHODS: We compared cesarean rates according to mode of onset of labor among 5,046 low-risk patients. Violation of the guidelines was defined as induction before 38 weeks or with a Bishop score <5 or with prostaglandins. The cesarean risk was analysed with a bivariable and then a multivariable analysis, which used a multilevel logistic model. RESULTS: Women with electively induced and spontaneous labor had identical cesarean rates (4.1%). The guidelines were not followed in 23.2% of elective inductions. The risk of cesarean was higher after induction with a Bishop score <5, than after spontaneous labor (adjusted OR=4.1, 95% CI [1.3-12.9]), while elective induction with a favourable cervix did not increase the cesarean risk. In nulliparas, failure to follow the guidelines tripled the risk of cesarean (adjusted OR=3.2 [1.0-10.2]). On the other hand, elective induction of labor for women with a favourable cervix did not increase the risk of cesarean over the risk with spontaneous labor. CONCLUSION: Elective induction does not appear to increase the cesarean rate when the guidelines are met. Electively inducing labor with a low Bishop score increased the risk of cesarean, especially in nulliparas.     

Risk of cesarean delivery after induction at term in nulliparous women with an unfavorable cervix

OBJECTIVE: The purpose of this study was to evaluate the effect of induction on the route of delivery in nulliparous women laboring at term in a community hospital system. STUDY DESIGN: From April 1997 to October 1999, there were 7282 deliveries in nulliparous patients who met inclusion criteria. Cesarean delivery rates were calculated for patients in spontaneous labor and for patients who underwent induction. RESULTS: Among 4635 women (63.7%) in spontaneous labor, the cesarean delivery rate was 11.5% versus 23.7% among the 2647 (36.3%) patients who underwent induction. An important variable that affected the delivery route was the Bishop score at the initiation of the induction. The cesarean delivery rate was 31.5% among patients whose Bishop score was <5 at induction versus 18.1% for patients with a score > or =5(P <.001). CONCLUSION: The induction of labor in nulliparous patients, especially those women with an unfavorable cervix as measured by Bishop score, is associated with a significantly increased risk of cesarean delivery.     

A randomized controlled trial of acupuncture for initiation of labor in nulliparous women.

OBJECTIVE: To evaluate the utility of outpatient acupuncture for labor stimulation. METHODS: Nulliparous women at 39 4/7 weeks or greater with a singleton gestation and Bishop score of less than 7 were randomized to usual medical care (control group) versus usual care and three outpatient acupuncture treatments (acupuncture group). Each treatment consisted of eight needles applied to bilateral points LI4, SP6, UB31, and UB32. The primary outcome was time elapsed from the time of randomization to delivery. Secondary outcomes included rates of cesarean section and induction of labor. Medical records were abstracted for maternal demographic, medical, and delivery outcome data. A priori sample size calculation revealed that 56 women were required to detect a 72-hour difference in delivery time with a power of 83% and an alpha of 0.05. Student's t-test, Chi-square, and Kaplan-Meier statistics were used to compare groups. RESULTS: Fifty-six women were randomized and completed the study procedures. Race, age, gestational age, and cervical Bishop score were similar in both groups. Mean time to delivery occurred 21 hours sooner in the acupuncture group, but this difference did not reach statistical significance (p = 0.36). Compared to controls, women in the acupuncture group tended to be more likely to labor spontaneously (70% vs. 50%, p = 0.12) and less likely to deliver by cesarean section (39% vs. 17%, p = 0.07). Of women who were not induced, those in the acupuncture group were more likely to be delivered than the controls at any point after enrollment (p = 0.05). CONCLUSION: Acupuncture is well tolerated among term nulliparous women and holds promise in reducing interventions that occur in post-term pregnancies.     

Macrophages and not granulocytes are involved in cervical ripening

To clarify the role of leucocytes in human cervical ripening and dilatation, cervical biopsies were obtained from six non-pregnant women, eight women undergoing early termination of pregnancy, 18 pregnant women undergoing elective Caesarean section at term (both with and without a ripe cervix as determined by Bishop score) and 11 women after term vaginal delivery. Leucocytes were localised by immunohistochemistry labelling and quantified in subepithelial and deep stromal areas. CD45+ leucocytes were more numerous in the subepithelial area of the cervix than in the deep stroma in all groups (P<0.01). CD14+ macrophages and CD15+ granulocytes were increased in both the subepithelial and deep stromal areas only in the vaginal delivery group (P<0.01). The number of macrophages in the ripening cervix (Bishop score above 4) was higher than in the unripe cervix (Bishop score 4 or less; P<0.05) with no differences in other leucocyte populations. CD3+ CD8+ T cells in the subepithelial area were reduced in late pregnancy and after vaginal delivery (P<0.01), but showed no relationship to Bishop score. Macrophages and granulocytes may be involved in the process of cervical dilatation, but macrophage infiltration into the ripening cervix before labour suggests their role in the ripening process. Reduced numbers of CD3+ CD8+ T-lymphocytes in late pregnancy and after vaginal delivery suggests that local immunity is down-regulated in the late pregnancy period. Regional differences in leucocyte subpopulations in the cervix indicate that leucocyte infiltration is likely to be regulated by local factors.     

Transcervical Foley catheter with and without extraamniotic saline infusion for labor induction: a randomized controlled trial

OBJECTIVE: To compare the efficacy of transcervical Foley catheter alone (Foley) to transcervical Foley catheter with extraamniotic saline infusion for labor induction and cervical ripening in women with an unfavorable cervix. METHODS: This was a multicenter, randomized, controlled trial of women presenting for labor induction with a singleton, cephalic fetus, intact membranes, and unfavorable cervix (Bishop score 6 or less). Eligible women were randomly assigned to receive either Foley catheter alone or Foley catheter with extraamniotic saline infusion. All women received concurrent oxytocin administration. The primary study outcome was the induction-to-delivery interval. Secondary outcomes included cesarean delivery, maternal infectious outcomes, and immediate neonatal outcomes. Analysis was by intent to treat. RESULTS: One hundred eighty-eight women met eligibility criteria and were randomly assigned (Foley plus extraamniotic saline infusion, n=97; Foley, n=91). Baseline demographic characteristics, including parity, gestational age, and Bishop score were similar between the study groups. The median induction-to-delivery interval in the extraamniotic saline infusion arm (12.6 hours, interquartile range 9.3-18.8 hours) was similar to that in the Foley arm (13.4 hours, interquartile range 9.6-17.5 hours) (P=. 70). The proportion of women delivered by 24 hours was comparable between groups (delivery 24 hours, extraamniotic saline infusion 89.7%, Foley 87.9%, P=.70), as was the rate of cesarean delivery (Foley 18.7%, extraamniotic saline infusion 27.8%, P=.14). No significant differences were noted between the study groups with respect to rate of chorioamnionitis, endometritis, or immediate birth outcomes. CONCLUSION: In women with an unfavorable cervix, the addition of extraamniotic saline infusion to a transcervical Foley catheter does not improve efficacy for labor induction. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00442663 LEVEL OF EVIDENCE: I.     

Unsucessful labour induction in women with unfavourable cervical scores: predictors and management

BACKGROUND: Misoprostol fails to induce labour in 5-20% of women at term. AIM: To analyse possible predictors of unsuccessful induction with 50 microg vaginal misoprostol and effectiveness and the safety of intracervical Foley catheter application in induction failures. METHODS: An observational study was conducted on 1030 women with singleton, live fetuses, vertex presentation, > 34 weeks of gestation and Bishop score < 5. Induction of labour with 50 microg vaginal misoprostol repeated every 6 h was attempted. Women without regular uterine contractions and cervical changes at the end of 24 h were considered to be unsuccessful, and a transcervical Foley balloon catheter was placed and inflated with 50 mL saline. Possible predictors of induction failures were analysed via logistic regression analysis. Neonatal outcomes and vaginal delivery achieved after Foley catheter were also determined. RESULTS: Induction was successful in 918 cases (89.1%) and Foley catheter was placed in 112 (10.8%) women. Increasing gestational age in weeks (odds ratio [OR] 0.77, 95% confidence interval [CI] 0.68-0.88) and increasing Bishop score (OR 0.73, 95% CI 0.60-0.90) decreased the risk of failed induction. Failure rates were 16% (27/169) in post-term nulliparous women with Bishop score 相似文献   

Effect of vaginal pH on efficacy of misoprostol for cervical ripening and labor induction

OBJECTIVE: We sought to evaluate whether vaginal pH has an effect on the relative efficacy of misoprostol for cervical ripening and labor induction. STUDY DESIGN: Thirty-seven gravid women with an unfavorable cervix and indication for labor induction were enrolled in this prospective, double-blind, observational study. Baseline assessments of cervicovaginal pH and Bishop score were made at the time of enrollment by an independent examiner. All patients received 50 microg misoprostol intravaginally every 6 hours for 12 hours. After the initial 12 hours of preinduction, a repeat Bishop score assessment was made by the same initial examiner. Patients not in active labor at 12 hours were placed on a standardized oxytocin induction regimen. Labor was managed by the on-call obstetric team, who remained blinded to pH assessment. Clinical outcomes were evaluated. Statistical analyses were made by the Student t test, the Fisher exact test, and linear regression analysis. RESULTS: Average initial vaginal pH was 4.8 +/- 0.5 (range, 3.5-7.0) for the study cohort. No significant differences were noted between those patients with low vaginal pH (< or =4.5) compared with those with high pH vaginal (>4.5) with respect to maternal age, parity, gestational age, or initial Bishop score. Similarly, Bishop score change over preinduction interval (5.6 vs 4.9), time to active labor (16.3 vs 17. 1 hours), time to complete dilatation (20.0 vs 19.9 hours), and time to delivery (21.0 vs 21.6 hours) were not significantly different between the low and high pH groups, respectively. Linear regression analysis revealed no significant association between vaginal pH and Bishop score change during preinduction interval, time to active labor, time to complete dilatation, or time to delivery. CONCLUSION: Vaginal pH does not appear to influence the efficacy of intravaginally administered misoprostol for cervical ripening and labor induction.     

Transvaginal ultrasound and digital examination in predicting successful labor induction.

OBJECTIVE: To compare transvaginal ultrasound and digital cervical examination in predicting successful induction in post-term pregnancy. METHODS: Transvaginal ultrasound and digital vaginal examinations were performed on 122 women at 41 or more weeks' gestation, immediately before labor induction. Ultrasound assessments of cervical length, dilatation, and presence of funneling were compared with the components of the Bishop score. The primary outcome was the rate of vaginal delivery. Secondary outcomes assessed included the rates of active labor in 12 hours, vaginal delivery in 12 and 24 hours, mean duration of latent phase, and induction to vaginal delivery interval. Linear and multiple logistic regression models were generated to identify factors independently associated with successful induction. RESULTS: No ultrasound characteristic predicted primary or secondary outcomes. Bishop score (odds ratio [OR] 2.98, 95% confidence interval [CI] 1.71, 5.20), cervical position (OR 4.35, 95% CI 1.41, 12.50), and maternal age (OR 1.15, 95% CI 1.01, 1.30) independently predicted vaginal delivery. Maternal weight (OR 0.96, 95% CI 0.94, 0.98), cervical dilatation (OR 6.08, 95% CI 1.70, 21.68), and effacement (OR 2.34, 95% CI 1.16, 4.73) independently predicted active labor in 12 hours. Independent predictors of vaginal delivery in 12 hours were induction method (P <.001), cervical dilatation (OR 11.16, 95% CI 3.17, 39.29), gravidity (OR 2.06, 95% CI 1.13, 3.77), and maternal weight (OR 0.96, 95% CI 0.93, 0.99). Cervical effacement (OR 2.70, 95% CI 1.59, 4.57) and parity (OR 7.10, 95% CI 2.22, 22.72) independently predicted vaginal delivery in 24 hours. Maternal weight, cervical position, and cervical dilatation were independently associated with latent phase labor duration. Factors independently associated with length of induction to delivery interval were parity, cervical effacement, and maternal weight. CONCLUSION: Transvaginal ultrasound does not predict successful labor induction in post-term pregnancy as well as digital cervical examination.     

The effect of vaginal administration of various doses of prostaglandin E2 gel on cervical ripening and induction of labor

Eighty patients with a Bishop score of less than or equal to 4 were randomly administered vaginal triacetin gel containing placebo or prostaglandin E2 in 1, 2, and 3 mg doses. Twelve to sixteen hours later, those not in labor underwent oxytocin induction. Increasing doses of prostaglandin were effective in ripening the cervix, and the higher doses were associated with significant success in inducing labor.     

Induction of labor in women with previous cesarean section using the double balloon device.

BACKGROUND AND METHODS: To evaluate the efficacy and safety of labor induction by the double balloon device in women with previous cesarean section. Induction of labor was carried out in 37 women with previous cesarean section for various indications. All the inductions of labor were performed using the Atad double balloon device (ARD). RESULTS: Cervical ripening (Bishop scores above 5) was achieved in 82.3% of the induced women with subsequent vaginal delivery in 78.6% and repeat cesarean section in 22.3%. An important observation of the results was the chances to achieve a vaginal delivery according to the second Bishop score that was recorded 12 hours following the insertion of the device. When the second was above 5 the chances for vaginal delivery were 79.4%. The mean time from removal of the device to delivery was 10.8 hours. No complications were noted using the device. CONCLUSIONS: The double balloon device appears to be a safe and effective method of inducing labor in women with a previous lower segment cesarean section. Wide scale studies and further use of the device for induction of labor in women who have had previous cesarean sections are warranted.     

Attempted vaginal birth after cesarean section: a multicenter comparison of outpatient prostaglandin E2 gel with expectant management

Objective: To compare the clinical effectiveness and safety of outpatient administration of an intracervical prostaglandin (PG) E₂ gel with expectant management for women with an unfavorable cervix who wish to attempt a vaginal birth after cesarean section.Study Design: This outpatient study was a randomized, multicenter investigation involving pregnant women at term with one previous low transverse cesarean section. Each had an unfavorable cervix (Bishop score ≤4) and was a candidate for vaginal delivery. Those randomly assigned to receive the gel, rather than expectant management, were given a 0.5 mg dose of PGE₂ (Prepidil) intracervically at 39 weeks gestation. This cervical ripening treatment was repeated at weekly office visits for up to 3 doses.Results: Of the 294 cases, 143 received the gel while 151 underwent expectant management. No differences between the two groups were found for maternal demographics, race, parity, or predose Bishop score. The rates of repeat cesarean section did not differ (P = .68) with use of the gel (61, 42%) or with expectant therapy (48, 45%). The onset of active labor, the duration of labor among those delivering vaginally, and the 1-minute and 5-minute Apgar scores were not different between the two groups. No uterine rupture was apparent, and adverse effects during labor were as likely to occur in the two groups.Conclusions: Although its safety was confirmed for outpatient use and for persons with a prior cesarean delivery, intracervical prostaglandin E₂ gel did not improve the chance of a vaginal birth after a cesarean delivery.     

Tocolysis during cervical ripening with vaginal PGE2

Forty-two primigravidae with unripe cervices (modified Bishop score less than or equal to 5) were pretreated with 8 mg of oral salbutamol 30 min before vaginal administration of 5 mg of PGE2. The proportion of patients in established labour after treatment (19%) was markedly less than results reported previously and cervical improvement occurred in 86% of the non-labouring patients. The improved outcome of labour associated with the prior administration of PGE2 when the cervix is unripe, including reduced induction-to-delivery intervals and higher rates of vaginal delivery was maintained. Apart from some minor side-effects, there were no adverse effects noted as a direct consequence of the tocolytic; blood loss was not increased, although one patient suffered an intrapartum abruption. This approach allows a greater control of induced uterine activity and timing of delivery which may be of particular importance in women with suspected placental insufficiency.     

Pre-induction intracervical application of a highly viscous prostaglandin E2 gel in pregnant women with an unripe uterine cervix: a double-blind placebo-controlled trial.

Intracervical application of prostaglandin E2 (PGE2) gel has shown to be an effective method for pre-induction cervical ripening in pregnant women with an unripe uterine cervix. Side effects are minimal, provided that the instillation is carefully restricted to the cervical canal. This requires--apart from a proper technique--an optimal gel formulation. For this reason a newly developed highly viscous PGE2 gel was evaluated in a randomized, double-blind, placebo-controlled multicentre trial. Within a 9-h study period, successful cervical ripening (increase in Bishop score to 6 or more) was achieved in 39 (56%) of the 70 patients in the PGE2 groups and in 23 (34%) of the 68% patients in the placebo group (P = 0.04). During the first 12 h after gel application, 25 (35%) of the women in the PGE2 group and 2 (3%) in the placebo group had a spontaneous delivery. No serious adverse reactions were observed. The data suggest that the use of this highly viscous PGE2 gel may be advantageous if strictly intracervical application is the primary objective.     

A study on the effect of dehydroepiandrosterone sulfate on so-called cervical ripening.

Dehydroepiandrosterone sulfate (DHAS) is now used for a dynamic test of placental function by many obstetricians. While practicing this test, the authors found that DHAS markedly promoted so-called "cervical ripening". To study this problem, DHAS of 50 or 100 mg in multiple doses were injected into 132 Japanese pregnant women in their 38th--42nd week of gestation. The change in Bishop score was carefully recorded. Bishop score in the injected groups of primiparae (100 mg) began to rise much sooner than the control groups (p less than 0.01 on seventh day and 14th day). However, such significant difference in the rise of Bishop score was not noted in the multiparae and primiparae with 50 mg. Although the rise of score is not significant, the duration (day) from injection to delivery was shorter in the injected group than the control group (t=2.1529, p less than 0.05 in primiparae with 50 mg, t=3.8829, p less than 0.01 with 100 mg, t=2.1029, p less than 0.05 in multiparae with 50 mg). In some of these cases, labor began or delivery was finished within 24 hrs. Among the factors of Bishop score, mainly the effacement, consistency and dilatation of the cervix were remarkably improved by DHAS injection (p less than 0.01 and less than 0.05). Side effects of any type were not seen in the mothers and foetuses. As a conclusion, DHAS injection in considered to produce favorable conditions for delivery in women with "unripe cervix" by softening the soft birth canal. Furthermore, it is suggested that DHAS might play an important role in triggering labor.