Predicting the spontaneous onset of labour in post-date pregnancies: a population-based retrospective cohort study.

OBJECTIVE: To estimate the probability of spontaneous onset of labour (SOL) among women with uncomplicated pregnancies who have reached 41+0 weeks and to examine the influence of maternal characteristics on this event. METHODS: We conducted a population-based retrospective cohort study of women with uncomplicated singleton pregnancies in cephalic presentation between 41+0 and 42+0 weeks' gestation. Detailed clinical information was obtained from the British Columbia Perinatal Data Registry. We determined the time from 41+0 weeks to the exact day and time of SOL, pre-labour Caesarean section, or onset of labour following induction. A Kaplan-Meier curve was created to estimate the probability of SOL. A Cox regression model was used to assess the independent influence of maternal age, parity, BMI, and pregnancy weight gain on the SOL, and to assess the extent to which prediction of SOL could be individualized according to a woman's characteristics. RESULTS: Among 15 253 women undelivered at 41+0 weeks, there was a 67.6% (95% CI 66.4% to 68.7%) chance of SOL by 41+6 weeks. Although SOL was statistically more likely in younger women, higher parity, lower BMI, and lower weight gain (P<0.01), the multivariable model's predictive ability was poor (c-statistic 0.56). CONCLUSION: Maternal characteristics were not a strong determinant for successful individualized prediction of SOL in women with uncomplicated pregnancies reaching 41+0 weeks of gestation. Our population-based estimates of the daily occurrence of SOL can be used to inform discussions with women on when to offer induction of labour.

Objectif : Estimer la probabilité du travail d'apparition spontanée (TAS) chez les femmes qui connaissent une grossesse exempte de complications atteignant 41+0 semaines et examiner l'influence des caractéristiques maternelles sur cet événement. Méthodes : Nous avons mené une étude de cohorte rétrospective en population générale qui portait sur les femmes connaissant une grossesse monofœtale exempte de complications en présentation céphalique entre 41+0 et 42+0 semaines de gestation. Nous avons tiré des renseignements cliniques détaillés du British Columbia Perinatal Data Registry. Nous avons déterminé le délai entre 41+0 semaines de gestation et la date et l'heure exactes du TAS, de la tenue d'une césarienne prétravail ou de l'apparition du travail à la suite d'un déclenchement. Une courbe Kaplan-Meier a été tracée pour estimer la probabilité du TAS. Un modèle de régression de Cox a été utilisé pour évaluer l'influence indépendante de l'âge maternel, de la parité, de l'IMC et du gain pondéral pendant la grossesse sur le TAS, ainsi que pour évaluer la mesure dans laquelle la prévision du TAS pourrait être personnalisée en fonction des caractéristiques de la patiente. Résultats : Chez 15 253 femmes n'ayant toujours pas accouché à 41+0 semaines, la probabilité de voir se manifester un TAS d'ici à 41+6 semaines était de 67,6 % (IC à 95 %, 66,4 % - 68,7 %). Bien que le TAS ait été plus probable sur le plan statistique chez les femmes présentant un âge moindre, une parité accrue, un IMC moindre et un gain pondéral moindre (P < 0,01), la valeur de prévision du modèle multivarié était faible (c-statistic : 0,56). Conclusion : Les caractéristiques maternelles ne constituaient pas un déterminant solide aux fins de la réussite de la prévision personnalisée du TAS chez les femmes qui connaissaient une grossesse exempte de complications atteignant 41+0 semaines de gestation. Nos estimations en population générale quant à la manifestation quotidienne du TAS peuvent être utilisées pour éclairer les discussions menées avec les femmes quant à la détermination du moment propice à l'offre d'un déclenchement du travail.

Caesarean section on maternal request: risks and benefits in healthy nulliparous women and their infants.

OBJECTIVE: To determine the risks and benefits of an elective Caesarean section (CS) at term in healthy nulliparous women. METHODS: We conducted a population-based cohort study of deliveries between 1994 and 2002. Using bivariate and multivariable techniques, we compared maternal and neonatal outcomes in healthy nulliparous women who had undergone elective pre-labour CS (using breech presentation as a surrogate) with those in women who had undergone spontaneous labour with anticipated vaginal delivery (SL) at full term. RESULTS: There were 1046 deliveries in the pre-labour CS group and 38 021 in the SL group. Life-threatening maternal morbidity was similar in each group. Life-threatening neonatal morbidity was decreased in the CS group (RR 0.34; 99% CI 0.12 to 0.97). Subgroup analysis of the SL group by mode of delivery demonstrated the increased neonatal risk was associated with operative vaginal delivery and intrapartum CS but not spontaneous vaginal delivery. CONCLUSION: An elective pre-labour Caesarean section in a nulliparous woman at full term decreased the risk of life-threatening neonatal morbidity compared with spontaneous labour with anticipated vaginal delivery. However, the 63% of women with spontaneous labour who achieved a spontaneous vaginal delivery would not have benefited from delivery by Caesarean section. Further research is needed to better identify women with an increased likelihood of an operative vaginal or intrapartum Caesarean section, as this may assist maternity caregivers in decision-making about childbirth. Further research is also needed to determine if these findings can be confirmed in a prospective study.

Fetomaternal hemorrhage during external cephalic version.

OBJECTIVE: To estimate the frequency and volume of fetomaternal hemorrhage during external cephalic version for term breech singleton fetuses and to identify risk factors involved with this complication. METHODS: A prospective observational study was performed including all patients undergoing a trial of external cephalic version for a breech presentation of at least 36 weeks of gestation between 1987 and 2001 in our center. A search for fetal erythrocytes using the standard Kleihauer-Betke test was obtained before and after each external cephalic version. The frequency and volume of fetomaternal hemorrhage were calculated. Putative risk factors for fetomaternal hemorrhage were evaluated by chi(2) test and Mann-Whitney U test. RESULTS: A Kleihauer-Betke test result was available before and after 1,311 trials of external cephalic version. The Kleihauer-Betke test was positive in 67 (5.1%) before the procedure. Of the 1,244 women with a negative Kleihauer-Betke test before external cephalic version, 30 (2.4%) had a positive Kleihauer-Betke test after the procedure. Ten (0.8%) had an estimated fetomaternal hemorrhage greater than 1 mL, and one (0.08%) had an estimated fetomaternal hemorrhage greater than 30 mL. The risk of fetomaternal hemorrhage was not influenced by parity, gestational age, body mass index, number of attempts at version, placental location, or amniotic fluid index. CONCLUSION: The risk of detectable fetomaternal hemorrhage during external cephalic version was 2.4%, with fetomaternal hemorrhage more than 30 mL in less than 0.1% of cases. These data suggest that the performance of a Kleihauer-Betke test is unwarranted in uneventful external cephalic version and that in Rh-negative women, no further Rh immune globulin is necessary other than the routine 300-microgram dose at 28 weeks of gestation and postpartum. LEVEL OF EVIDENCE: II.

A randomized trial comparing oral misoprostol with intra-amniotic prostaglandin F2alpha for second trimester terminations.

OBJECTIVE: To compare the efficacy of oral misoprostol with that of intra-amniotic prostaglandin F2alpha (PGF2alpha) for second trimester pregnancy termination. METHODS: One hundred seventeen women with pregnancies of between 16 and 22 weeks' gestation were randomly assigned after insertion of laminaria to receive either oral misoprostol 400 microg every 4 hours (to a maximum of four doses) or intra-amniotic PGF2alpha 40 mg. The rate of complete abortion within 24 hours was the primary outcome for power analysis. Secondary outcome measures were the rate of dilatation and curettage (D&C) for retained placenta and the rates of fever and gastrointestinal complications. RESULTS: Patient characteristics were similar in both groups. The rate of complete abortion within 24 hours was similar in the misoprostol (63%) and PGF2alpha (66%) groups. The rate of retained placenta requiring D&C was significantly greater in the PGF2alpha group (22.4% vs. 3.4%, P = 0.002). There were no differences in other maternal morbidities. Parous patients treated with oral misoprostol had a significantly greater rate of complete abortion than nulliparous patients (84% vs. 57%, P = 0.04). CONCLUSIONS: Oral misoprostol is as effective as intra-amniotic PGF2alpha for second trimester pregnancy termination when laminaria is inserted before treatment. Parous patients have a higher success rate than nulliparous patients with use of oral misoprostol. Oral misoprostol is associated with a very low rate of placental retention.

The relationship between amniotic fluid index and successful external cephalic version: a 14-year experience.

OBJECTIVE: This study was undertaken to assess the association between amniotic fluid index (AFI), success of external cephalic version (ECV), and obstetric outcome in patients undergoing ECV. STUDY DESIGN: A prospective observational study was performed that included all patients who had a trial of ECV from 1987 to 2000 in our center. Rates of success, fetal heart decelerations during trial at ECV, and cesarean deliveries were calculated. Groups were divided by an AFI performed immediately before ECV: AFI less than 10 cm, 10 to 15 cm, and more than 15 cm. RESULTS: In our group of 1361 patients undergoing ECV, the rate of success was related to the AFI in both parous women (49.1%, 63.5% and 72.1% [P<.001] for each AFI group, respectively) and nulliparous women (36.5%, 43.6%, and 57.3% [P<.001]). The rate of cesarean section delivery was related to AFI in nulliparous but not multiparous patients (P<.001). The rate of prolonged fetal heart rate decelerations was not significantly related to the AFI. CONCLUSION: The rate of successful ECV and cesarean section deliveries is related to the amniotic fluid volume. This information may be used to consent patient before a trial of ECV.

Sublingual nitroglycerin versus intravenous ritodrine as tocolytic for external cephalic version: a double-blinded randomized trial.

OBJECTIVE: The purpose of this study was to compare the efficacy of sublingual nitroglycerin with that of intravenous ritodrine as a tocolytic agent for external cephalic version in nulliparous women. STUDY DESIGN: We performed a double-blinded, randomized trial. Nulliparous patients, between 36 and 40 weeks of gestation, were assigned randomly to receive either (1) an intravenous infusion of ritodrine (111 microg/min) for 20 minutes, followed by two puffs of sublingual placebo or (2) an intravenous infusion of sodium chloride 0.9% (placebo) for 20 minutes, followed by two puffs of sublingual 0.4 mg of nitroglycerin. Three minutes after the administration of the sublingual spray, an external cephalic version was attempted. The rate of successful external cephalic version and side effects was compared between groups. RESULTS: Of 74 randomly assigned patients, 38 patients received intravenous ritodrine, and 36 patients received sublingual nitroglycerin. Although not statistically significant, the rate of the successful external cephalic version was higher in the ritodrine group compared with the nitroglycerin group (45% vs 25%, P =.075). The rate of headaches was higher in patients who received nitroglycerin (28% vs 8%, P =.02). Mean blood pressure and maternal heart rate were lower in the nitroglycerin group 10 minutes after the administration of the medication. However, there was no significant difference in the rate of palpitations, hypotension, or fetal bradycardia between the two groups. CONCLUSION: When compared with intravenous ritodrine, sublingual nitroglycerin was associated with a higher rate of headache, lower blood pressure, and a trend toward a lower rate of successful external cephalic version.

Sublingual nitroglycerin versus placebo as a tocolytic for external cephalic version: a randomized controlled trial in parous women.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of sublingual nitroglycerin as a tocolytic agent for external cephalic version in parous women. STUDY DESIGN: A double-blinded randomized controlled trial was performed. Patients with parity of >or=1 at 36 to 40 weeks of gestation who were eligible for external cephalic version were included. Patients were randomized to receive either two sublingual sprays of 400 mug of nitroglycerin or two sprays of placebo 3 minutes before the trial of external cephalic version. Rates of successful external cephalic version and side effects were compared between groups. RESULTS: Of 99 patients in the study, 50 patients received sublingual nitroglycerin, and 49 patients received placebo. There were no differences in maternal age, gestational age, estimated fetal weight, amniotic fluid index, and placental location between the two groups. The success rate of external cephalic version was 48% in the nitroglycerin group compared with 63% in the placebo group (P=.13). There was a higher incidence of headaches in the nitroglycerin group (42% vs 4%, P<.001). CONCLUSION: Sublingual nitroglycerin was associated with a higher rate of headache and did not improve the rate of successful external cephalic version.

Cesarean delivery after successful external cephalic version of breech presentation at term: a comparative study.

OBJECTIVE: The purpose of this study was to evaluate the rate and indications of cesarean delivery after a successful external cephalic version. STUDY DESIGN: A case-control study was performed from patients who were delivered in a tertiary care center between 1987 and 2000. Each patient who underwent a successful external cephalic version (study group) was compared with the next woman with the same parity, who was delivered at term (control group). Nulliparous and multiparous women were analyzed separately. Chi-squared, Mann-Whitney, and Student t tests were used for statistical analysis. Multivariate logistic regression analysis was performed where appropriate. RESULTS: A total of 602 patients were included in this study. The rates of cesarean delivery in nulliparous women (29.8% vs 15.9%; P<.001) and in multiparous women (15.9% vs 4.7%; P<.001) were significantly higher when compared with the control group. Patients with successful external cephalic version were more likely to have a cesarean delivery for dystocia (nulliparous, 22.5% vs 11.9%; P=.01; multiparous, 10.9% vs 1.3%; P<.01). After an adjustment for confounding variables, a successful external cephalic version was associated with an increased rate of cesarean delivery at term (nulliparous: odds ratio, 2.04; 95% CI, 1.13-3.68; multiparous: odds ratio, 4.30; 95% CI, 1.76-10.54). CONCLUSION: The rate of cesarean delivery for dystocia is increased after a successful trial of external cephalic version in both nulliparous and multiparous women.