Epidural analgesia and severe perineal tears: a literature review and large cohort study

Abstract

Objective: Our objectives were to study the association between epidural analgesia and risk of severe perineal tears (SPT), and identify additional risk factors for SPT.

Methods: We conducted a historical cohort study of women with term delivery between 2006 and 2011. Inclusion criteria were an uncomplicated singleton pregnancy, cephalic presentation and vaginal delivery. Multivariate logistic regression models were constructed to study the association between epidural analgesia and SPT, controlling for potential confounders. Additional models studied the association between prolonged second stage and instrumental labor and SPT.

Results: During the study period, 61?308 eligible women gave birth, 31?631 (51.6%) of whom received epidural analgesia. SPT occurred in 0.3% of births. Deliveries with epidural had significantly higher rates of primiparity, induction and augmentation of labor, prolonged second stage of labor, instrumental births and midline episiotomies. The univariate analysis showed a significant association between the use of epidural and SPT (OR: 1.78, 95% CI: 1.34–2.36); however, this association disappeared when parity was introduced (OR: 0.95, 95% CI: 0.69–1.29). Instrumental deliveries and prolonged second stage of labor were both strongly associated with SPT (ORs of 1.82 and 1.77)

Conclusions: Epidural analgesia was not associated with SPT once confounding factors were controlled for.     

Induction of labor in twin gestation: lessons from a population based study

Introduction: The route of delivery and the role of induction of labor in twin gestations are controversial. The aim of this study was to determine the efficacy of induction of labor in twin gestations.

Methods: This retrospective population based cohort study included 4605 twin gestations divided into following groups: 1) spontaneous parturition (n?=?2937, 63.78%); 2) induction of labor (n?=?653, 14.2%) and 3) elective cesarean delivery (n?=?1015, 22.04%).

Results: The rate of vaginal delivery in the labor induction group was 81% (529/653). In comparison to the other study groups, induction of labor in twins was independently associated with a 77% reduction in the risk of cesarean delivery (OR 0.23; 95% CI 0.18–0.31) and a 78% reduction in the risk of postpartum death for the second twin (OR 0.22; 95% CI 0.05–0.94). The rate of nulliparity, term delivery and labor dystocia was higher in the induction of labor group (p?<?0.001 in all comparisons).

Conclusions: Our results suggest that induction of labor in twin gestation is successful and is independently associated with substantial reduction in the risk of cesarean delivery and postpartum death of the second twin.     

Does dystocia during labor pose a risk factor for another non-progressive labor during the subsequent delivery?

Objective: To establish whether failure to progress during labor poses a risk factor for another non-progressive labor (NPL) during the subsequent delivery.

Methods: A retrospective cohort study including singleton pregnancies that failed to progress during the previous labor and resulted in a cesarean section (CS) was conducted. Parturients were classified into three groups for both previous and subsequent labors: CS due to NPL stage I, stage II and an elective CS as a comparison group.

Results: Of 202?462 deliveries, 10?654 women met the inclusion criteria: 3068 women were operated due to NPL stage I and 1218 due to NPL stage II. The comparison group included 6368 women. Using a multivariable logistic regression models, NPL stage I during the previous delivery was found as an independent risk factor for another NPL stage I in the subsequent labor (adjusted odds ratio [OR]?=?2.9; 95% confidence interval [CI]?=?2.4–3.7; p?p?=?0.033; adjusted OR?=?5.3; 95% CI?=?3.7–7.5; p?Conclusion: A previous CS due to a NPL is an independent risk factor for another NPL in the subsequent pregnancy and for recurrent cesarean delivery.     

Safety of vaginal delivery in very low birthweight vertex singletons: a meta-analysis

Objective: The objective of this study is to assess the safety of vaginal delivery in VLBW singletons in the vertex presentation.

Methods: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Web of Science databases were searched for studies on mode of delivery and neonatal outcome in VLBW singletons in the vertex presentation. A total of 28 studies met our inclusion criteria.

Results: Vaginal delivery was not associated with an increase in overall neonatal mortality compared with cesarean delivery (OR 0.87, 95% CI 0.72–1.04). Vaginal delivery was associated with a significant decrease in mortality for the 1250–1500?g birthweight category (OR 0.57, 95% CI 0.36–0.92), while an increase in mortality in the 500–750?g category was not significant (OR 1.5, 95% CI 0.86–2.61). Severe intraventricular hemorrhage (IVH) was not associated with mode of delivery (OR 1.05, 95% CI 0.85–1.29), but the only two high quality study that assessed IVH of all grades found an increase in risk for IVH in vaginal delivery (OR 1.33, 95% CI 1.16–1.51).

Conclusions: Vaginal delivery does not appear to increase the risk for neonatal mortality. However, current available data on neonatal morbidity are limited. More high-quality studies are needed to assess the association between mode of delivery and neonatal morbidity.     

Symphysiolysis as an independent risk factor for cesarean delivery

Objectives.?To investigate whether symphysiolysis during pregnancy is a risk factor for cesarean delivery (CD).

Methods. A retrospective population-based study comparing all singleton pregnancies of women with and without symphysiolysis was conducted. Deliveries occurred between the years 2000 and 2007. Multiple logistic regression models were used to control for confounders.

Results.?Out of 80,898 patients, 0.2% (n?=?154) were diagnosed with symphysiolysis during pregnancy. Patients with symphysiolysis were significantly older as compared to the comparison group. These patients had higher rates of mild pre-eclampsia, gestational diabetes mellitus (GDM) and labor induction as compared to patients without symphysiolysis. Higher rates of CD were noted in pregnancies complicated by symphysiolysis [22.1% vs. 15.9%; Odds ratio (OR)?=?1.5, 95% confidence interval (CI) 1.02–2.2; P?=?0.036]. Using multiple logistic regression model, with symphysiolysis as the outcome variable, controlling for labor induction, mild pre-eclampsia and GDM, symphysiolysis was noted as an independent risk factor for CD (weighted OR?=?1.7, 95% CI 1.1–2.5; P?=?0.009). Perinatal outcomes such as low Apgar scores (<7) at 1 and 5?min and perinatal mortality were comparable between the groups.

Conclusions.?Symphysiolysis is an independent risk factor for CD.     

Method of delivery and intraventricular haemorrhage in extremely preterm infants

Objectives.?It has been reported that caesarean delivery (CD) protects against intraventricular haemorrhage (IVH) in the extremely preterm infant, but it is not known whether this effect involve the more severe grades of IVH. Thus, our aim was to confirm the correlation between the occurrence of IVH and the mode of delivery, and to evaluate this correlation for each grade of IVH.

Methods.?All infants with gestational age (GA)?≤?28 weeks admitted to the neonatal intensive care unit of a tertiary hospital were studied for each grade IVH and major complications rate.

Results.?We found that vaginally born infants had a higher rate of each grade of IVH, but the increase was statistically significant only for grade 3 IVH (18% vs. 2%, p?<?0.0001) and all grades IVH (45% vs. 20%, p?<?0.0001). Multivariate analysis demonstrated that CD (RR: 0.42, 95% CI 0.28–0.63), birth weight?≥?800?g (RR: 0.48, 95% CI 0.32–0.73), 27–28 weeks of GA (RR: 0.38, 95% CI 0.25–0.60) and antenatal steroids (0.66, 95% CI 0.22–0.46) decrease independently the risk of developing IVH.

Conclusions.?Our study demonstrates that CD decreases the risk of developing IVH in extremely preterm infants including the most severe grades of IVH.     

Evaluation of risk factors in women with puerperal genital hematomas

Aim: Our aim was to assess the incidence and risk factors of the puerperal genital hematomas (PGH).

Methods: We retrospectively reviewed recorded cases of PGH at Zekai Tahir Burak Research and Training Hospital, Ankara, Turkey, between January 2010 and 2014. Next three patients were chosen as control group.

Results: There were 47 cases of PGH with an incidence of 1 in 762 deliveries. Patients with PGH were younger, more likely to be nulliparous and had a greater weight gain during pregnancy than the control group. Patients with PGH had a longer first and second stage of labor than the control group. Mediolateral episiotomy and operative delivery were more frequently performed in patients with PGH than the control group. Neonates born to mothers with PGH were heavier than the control group (3525?±?428 versus 3325?±?579; p?=?0.031). In the logistic regression model, nulliparity (OR: 8.68, 95% CI?=?2.96–25.3), instrumental delivery (OR: 7.96, 95% CI?=?1.37–49.0) and mediolateral episiotomy (OR: 6.67, 95% CI?=?2.61–17.1) were factors which had an independent impact on risk of PGH.

Conclusions: Nulliparity, instrumental delivery and mediolateral episiotomy are the main risk factors for hematomas.     

Excessive weight gain and hypertensive disorders of pregnancy in the obese patient

Objective: To evaluate the association between excessive weight gain and pregnancy-related hypertension (PRH) among obese women (body mass index (BMI) ≥30?kg/m²).

Methods: We performed a case control study among women with (n?=?440) and without (n?=?600) PRH from 2005 to 2007. Height and weight were recorded at initial and final prenatal visits. 695 women had BMI recorded at ≤18 weeks of gestation, of which 257 (36.9%) were obese. Obese women were divided into three categories based on 2009 Institute of Medicine (IOM) guidelines: (1) below recommended amount (under weight gain – UWG); (2) more than recommended (excessive weight gain – EWG) or (3) within recommended amount (normal weight gain – NWG). PRH was defined as gestational hypertension, mild or severe preeclampsia. Patients with and without PRH were prospectively identified. The association between weight gain category and development of PRH was analyzed.

Results: We noticed a 1.5-fold higher odds of having PRH with an initial BMI ≥30?kg/m² compared to BMI <30?kg/m² (OR 1.64, 95% CI 1.2–2.2, p?=?0.002). Among obese women, we noted a 2-fold higher odds of having PRH with EWG compared to NWG (OR 2.52, 95% CI 1.2–3.9, p?=?0.012). The increased odds persisted after adjusting for race, chronic hypertension and diabetes, and length of gestation (AOR 2.61, 95% CI 1.4–4.9, p?=?0.003). Among obese women with PRH, those with EWG had a 76% decreased odds of having severe disease compared to NWG (OR?=?0.242 [0.07–0.79], p?=?0.019).

Conclusion: We have demonstrated that EWG among obese patients increases overall risk of PRH.     

The association between nitroglycerin use and adverse outcomes in women undergoing cesarean delivery in the second stage of labor

Objective: To identify predictors of hysterotomy extension in women undergoing cesarean delivery (CD) in the second stage of labor, and whether use of nitroglycerin (NTG) during CD has a protective effect.

Methods: We conducted a retrospective cohort study of women undergoing CD in the second stage of labor from 2012 to 2015. Some women received NTG at the obstetrician’s request. Logistic regression was used to examine the relationship between second stage duration and NTG administration on maternal and neonatal outcomes.

Results: Of the 391 women in the sample, 27% had an extension and 12% received NTG. Second stage?≥4?h was associated with a 2.14-fold higher risk of extension (95% CI 1.22–3.75), a 2.00-fold higher risk of hemorrhage (95% CI: 1.20–3.33) and 2.42-fold higher risk of blood transfusion during delivery hospitalization (95% CI: 0.99–5.91). Intravenous (IV) and sublingual-spray (SL-spray) NTG administration were not associated with an increased risk of hemorrhage or extension. SL-NTG was associated with 4.68-fold increased odds of 5-min Apgar?<7 (95% CI 1.42–15.41) and 3.36-fold greater odds of NICU admission (95% CI 1.20–9.41).

Conclusion: We found no evidence that NTG protects against extension, and SL-NTG use was associated with adverse neonatal outcomes. Clinical trials should be conducted to evaluate risk and benefits of NTG use.     

Calcium level during the first trimester of pregnancy as a predictor of preeclampsia

Objective: To examine the association between calcium levels during the first trimester of pregnancy and preeclampsia. Methods: The study population included registered births (n?=?5233) in a tertiary medical center between 2001 and 2011. A comparison was performed between women with and without hypocalcemia during the first trimester of pregnancy. A second analysis was performed after correcting calcium levels for albumin. Multiple logistic regression models were used to control for confounders. Receiver operating characteristic curve analysis graphs were used to describe the relationship between the true-positive rate (sensitivity) and the false-positive rate for different values of calcium during the first half of pregnancy in the prediction of preeclampsia. Results: Of 5233 deliveries, 841 (16%) had hypocalcemia and 4392 (84%) had a normal calcium level. No significant difference were found between the groups regarding mild preeclampsia [odds ratio (OR) = 1.216; 95% confidence interval (CI) 0.831–1.779; p?=?0.312], severe preeclampsia (OR?=?1.618; 95% CI 0.919–2.849; p?=?0.092) and any hypertensive disorders (OR?=?1.324; 95% CI 0.963–1.821; p?=?0.083). Conclusions: Hypocalcemia during the first trimester of pregnancy is not a risk factor for preeclampsia.     

Measurement of interleukin-6 (IL-6) and erythropoietin (EPO) in umbilical cords of preterm infants with intraventricular hemorrhage in two hospitals in Tehran

Background: Intraventricular hemorrhage (IVH) is an important cause of death in premature infants. This study aimed to assess the association of the umbilical cord plasma levels of interleukin-6 (IL-6) and erythropoietin (EPO) with the occurrence and severity of IVH in premature infants.

Methods: Fifty premature newborns of mothers with chorioamnionitis risk factor were selected via nonprobability sampling. The concentration of the cord plasma’s IL-6 and erythropoietin were measured by enzyme-linked immunosorbent assay (ELISA) for 3 days. Finally, all samples underwent sonography for the diagnosis of IVH. Results analyzed statistically.

Results: Among the samples, 68.98% of them were diagnosed with IVH grade 1. The most severe IVH cases were detected on the second day. The mean and standard deviation of IL-6 level was 74.71?±?50.53 in the case group and 24.10?±?46.10 in the control group. There was a correlation between IL-6 levels and IVH (p?=?0.0005). The mean and standard deviation of EPO level was 18.38?±?15.23 in the IVH group and 6.45?±?13.48 in samples without IVH. A correlation was detected between EPO level and IVH (p?=?0.005).

Conclusion: The concentration of IL-6 and EPO levels of the cord plasma was higher in the premature newborns with IVH.     

Obstetric and neonatal outcome in patients with anxiety disorders

Abstract

Objective: To investigate whether a diagnosis of anxiety disorder is a risk factor for adverse obstetric and neonatal outcome.

Methods: A retrospective population-based study was conducted comparing obstetric and neonatal complications in patients with and without a diagnosis of anxiety. Multivariable analysis was performed to control for confounders.

Results: During the study period 256?312 singleton deliveries have occurred, out of which 224 (0.09%) were in patients with a diagnosis of an anxiety disorder. Patients with anxiety disorders were older (32.17?±?5.1 versus 28.56?±?5.9), were more likely to be smokers (7.1% versus 1.1%) and had a higher rate of preterm deliveries (PTD; 15.2% versus 7.9%), as compared with the comparison group. Using a multiple logistic regression model, anxiety disorders were independently associated with advanced maternal age (OR 1.087; 95% CI 1.06–1.11; p?=?0.001), smoking (OR 4.51; 95% CI 2.6–7.29; p?=?0.001) and preterm labor (OR 1.92; 95% CI 1.32-–2.8; p?=?0.001). In addition, having a diagnosis of an anxiety disorder was found to be an independent risk factor for cesarean section (adjusted OR 2.5; 95% CI 1.82–3.46; p?<?0.001), using another multivariable model. No association was noted between anxiety disorders and adverse neonatal outcomes including small for gestational age, low Apgar scores and perinatal mortality.

Conclusion: Anxiety disorders are independent risk factors for spontaneous preterm delivery and cesarean section, but in our population it is not associated with adverse perinatal outcome.     

Population-based study on antenatal corticosteroid treatment in preterm small for gestational age and non-small for gestational age twin infants

Objectives: To assess the associations between antenatal corticosteroid use (ACU), mortality and severe morbidities in preterm, twin neonates and compare these between small for gestational age (SGA) and non-SGA twins.

Materials and methods: Population-based study using data collected by the Israel National Very Low Birth Weight infant database from 1995 to 2012, comprising twin infants of 24–31 weeks' gestation, without major malformations. Univariate and multivariable logistic regression analyses were performed.

Results: Among the 6195 study twin infants, 784 were SGA. Among SGA neonates, ACU were associated with decreased mortality (23.9% vs. 39.2%, p?p?=?0.0015), similar to the effect in non-SGA neonates (mortality 13.0% vs. 24.5%, p?p?P_interaction?=?0.69. Composite adverse outcome risk was also reduced in SGA (OR?=?0.78, 95% CI 0.50–1.23) and non-SGA groups (OR?=?0.78, 95% CI 0.65–0.95), P_interaction?=?0.95.

Conclusions: ACU should be considered in all mothers with twin gestation, at risk for preterm delivery at 24–31 weeks, in order to improve perinatal outcome.     

Does gender of the fetus have any relation with fetal heart monitoring during the first and second stage of labor?

Objective: To investigate fetal gender and its influences on neonatal outcomes, taking into consideration the available tools for the assessment of fetal well-being.

Methods: We conducted a retrospective study comparing maternal, fetal and neonatal outcomes according to fetal gender, in women carrying a singleton gestation.

A multivariate analysis was performed for the prediction of adverse neonatal outcomes according to fetal gender, after adjustment for gestational age, maternal age and fetal weight.

Results: A total of 682 pregnancies were included in the study, of them 56% (n?=?383) were carrying a male fetus and 44% (n?=?299) a females fetus. Male gender was associated with a significant higher rate of abnormal fetal heart tracing patterns during the first (67.7% versus 55.1, p?=?0.001) and the second stage (77.6 versus 67.7, p?=?0.01) of labor. Male gender was also significantly associated with lower Apgar scores at 1' (19.1% versus 10.7%, p?p?2, PO₂) compared with female fetuses. In the multivariate analysis, male gender was found to be significantly associated with first (OR 1.76, 95% CI 1.28–2.43, p?=?0.001) and second stage (OR 1.73, 95% CI 1.20–2.50, p?Conclusions: The present study confirms the general trend of a lower clinical performance of male neonates compared with females. In addition, the relation between fetal heart rate patterns during all stages of labor and fetal gender showed an independent association between male fetal gender and abnormal fetal heart monitoring during labor.     

Uterine electric activity during the third stage of labor; a look into the physiology of a deserted stage

Abstract

Objective: To evaluate uterine activity during the third stage of labor and compare it to that observed in the second stage of labor.

Study design: Uterine electric activity was prospectively measured using electrical uterine myography (EUM) in 44 women with singleton pregnancy at term during the final 30?min of the second stage and throughout the third stage of labor. Results are reported using a scoring index of 1–5?mWS (micro-Watt-Second). Patients were stratified into two groups based on the duration of the third stage (<15?min and >=15?min)

Results: The mean durations of the second and third stages were 51.9?±?63.5 and 15.4?±?7.5?minutes, respectively. During the third stage, uterine activity (contractions peaks) was similar to that observed during the second stage of labor (3.43?±?0.64?mWS versus 3.42?±?0.57?mWS, p?=?0.8). No correlation was found between the duration of the third stage and EUM measurements during the third (p?=?0.9) or the second (p?=?0.2) stages of labor. No association was found between EUM measurements during the third stage and parity, maternal age, fetal weight, duration of labor, gestational age, gravity or BMI. The rate of oxytocin use during the second stage and EUM measurements during the second or third stage did not differ among women with short versus long duration of the third stage.

Conclusion: Uterine activity during the third stage is comparable and as intense as that occurring during the second stage. Third stage length cannot be predicted by contraction intensity during the second or third stage of labor.     

Multivariable evaluation of term birth weight: a comparison between ultrasound biometry and symphysis-fundal height

Abstract

Objective: To determine whether perineal massage during the second stage of labor using oil enriched with vitamins, increases the chances of delivering with an intact perineum as compared to perineal massage using pure liquid wax.

Method: A prospective, randomized, double-blind study was conducted. Women were assigned to liquid wax (jojoba oil) versus purified formula of almond and olive oil, enriched with vitamin B1, B2, B6, E and fatty acids. The caregivers used the oils during the second stage of labor.

Results: A total of 164 women undergoing vaginal delivery were recruited. No significant differences regarding perineal lacerations, number of sutures and length of suturing were noted between the two groups. Likewise, while analyzing separately nulliparous and multiparous women, no significant differences were noted. Controlling for birth weight >4000?g, using the Mantel–Haenszel technique, no association was noted between perineal lacerations and the type of oil used (weighted OR?=?0.9, 95% CI 0.3–2.4; p?=?0.818).

Conclusion: The type of the oil used during the second stage of labor for prevention of perineal tears has no effect on the integrity of the perineum. Accordingly, it seems that there is no perfect oil.     

Extreme maternal underweight and feto-infant morbidity outcomes: a population-based study

Objective. We sought to estimate the association between severity of maternal pre-pregnancy underweight and feto-infant morbidity outcomes.

Methods. Missouri maternally linked cohort records from 1989 to 1997 inclusive were analysed. Using pre-pregnancy maternal body mass index (BMI), we classified study participants into: Normal (18.5–24.9) [referent group], mild thinness (17.0–18.5), moderate thinness (16.0–16.9) and severe thinness (<16.0). We estimated the association between pre-pregnancy underweight, underweight subtypes and feto-infant morbidity outcomes using adjusted odds ratios to approximate relative risks with correction for intra-cluster correlations.

Results. Fetal growth curve trajectories for the two groups became divergent as from 30 gestational weeks. Underweight mothers were at increased risk for low birthweight (OR = 1.82; 95% CI = 1.77–1.88), very low birthweight (OR = 1.41; 95% CI = 1.31–1.51), small for gestational age (OR = 1.80; 95% CI = 1.76–1.84), preterm (OR = 1.37; 95% CI = 1.33–1.40) and very preterm (OR = 1.42; 95% CI = 1.34–1.50). These risk estimates increased in a dose-effect fashion with increasing severity of underweight status except for very preterm (p for trend < 0.01).

Conclusion. Pre-pregnancy underweight is a risk factor for a spectrum of feto-infant morbidity outcomes, with risk estimates being most pronounced among extremely underweight mothers.     

Duration of passive and active phases of the second stage of labour and risk of severe postpartum haemorrhage in low-risk nulliparous women

Objective

To assess the risk of severe postpartum haemorrhage (PPH) according to the durations of the passive and active phases of the second stage of labour.

Study design

Secondary analysis from the PREMODA prospective observational study in 138 French maternity units; 3330 low-risk nulliparous women with vaginal deliveries of cephalic singletons were included. Prospective analysis of the recorded durations of the active first stage of labour and the passive and active phases of the second stage of labour was undertaken, and their association with severe PPH, defined by estimated blood loss >1000 ml or blood transfusion. Factors associated with severe PPH were analysed by uni and multivariate analyses with logistic regression models.

Results

The frequency of severe PPH was 2.1% (n = 69). In the univariate analysis, the frequency of severe PPH increased with the duration of the active second stage but not the passive second stage: 1.2% for active second stage <10 min, 1.6% for 10–19 min, 2.1% for 20–29 min, 2.6% for 30–39 min, 4.5% for 40–49 min and 14.3% for ≥50 min (p < 0.001). After adjustment for confounding factors, the risk of severe PPH was found to be statistically significant when the active first stage exceeded 6 h [adjusted odds ratio (OR) 2.5, 95% confidence interval (CI) 1.0–6.1)] and when the active second stage exceeded 40 min (40–49 min: adjusted OR 3.5, 95% CI 1.0–12.3; ≥50 min: adjusted OR 10.6, 95% CI 2.8–40.3; reference: <10 min). The duration of the active second stage was not associated with other maternal or neonatal complications.

Conclusions

A prolonged active, but not passive, second stage of labour is associated with the risk of severe PPH in nulliparas. The optimal duration of these phases remains to be defined.     

Trial of labor after cesarean section in twin pregnancies: Maternal and neonatal safety

Objective.?To assess maternal and perinatal morbidity in patients undergoing a trial of labor after cesarean section (TOLAC) in twin gestations.

Methods.?A retrospective study including all twin pregnancies with a single prior cesarean section was performed. Stratified analysis using a multiple logistic regression model was performed to control for confounders. Patients who had a clear medical indication for a cesarean section (i.e. previous corporeal cesarean section, breech or transverse presentation, placenta previa, placental abruption, and herpes infection) were excluded from the analysis.

Results.?During the years 1988–2007, 134 patients met the inclusion criteria. Of these, 25 patients underwent a trial of labor and the remaining 109 underwent a repeat cesarean delivery. There were no cases of uterine rupture, maternal mortality, or peripartum fever in our population. Higher rates of perinatal mortality were noted in patients undergoing a trial of labor (8% vs. 1.8%, p?=?0.042, OR?=?4.652, 95% CI?=?1.122–19.286). However, a trial of labor was not found to be an independent risk factor for perinatal mortality after controlling for confounders such as gestational age, ethnicity, and fetal malformations (adjusted OR?=?1.07, 95% CI?=?0.07–15.95, p?=?0.95).

Conclusions.?A TOLAC is not associated with an increased risk for maternal morbidity, including uterine rupture. Nevertheless, in our population TOLAC was noted as a risk factor for perinatal mortality, although residual confounding cannot be excluded. Further prospective randomized studies should evaluate the safety of TOLAC in twin gestations to establish appropriate guidelines.     

Models for the prediction of successful induction of labor based on pre-induction sonographic measurement of cervical length

Objective.?To examine the effect of pre-induction cervical length, parity, gestational age at induction, maternal age and body mass index (BMI) on the possibility of successful delivery in women undergoing induction of labor.

Methods.?In 822 singleton pregnancies, induction of labor was carried out at 35 to 42^?+?6 weeks of gestation. The cervical length was measured by transvaginal sonography before induction. The effect of cervical length, parity, gestational age, maternal age and BMI on the interval between induction and vaginal delivery within 24?hours was investigated using Cox's proportional hazard model. The likelihood of vaginal delivery within 24?hours and risk for cesarean section overall and for failure to progress was investigated using logistic regression analysis.

Results.?Successful vaginal delivery within 24?hours of induction occurred in 530 (64.5%) of the 822 women. Cesarean sections were performed in 161 (19.6%) cases, 70 for fetal distress and 91 for failure to progress. Cox's proportional hazard model indicated that significant prediction of the induction-to-delivery interval was provided by the pre-induction cervical length (HR?=?0.89, 95 % CI 0.88–0.90, p?<?0.0001), parity (HR?=?2.39, 95% CI 1.98–2.88, p?<?0.0001), gestational age (HR?=?1.13, 95% CI 1.07–1.2, p?= <?0.0001) and birth weight percentile (HR?=?0.995, 95% CI 0.99?– 0.995, p?=?0.001), but not by maternal age or BMI. Logistic regression analysis indicated that significant prediction of the likelihood of vaginal delivery within 24?hours was provided by pre-induction cervical length (OR?=?0.86, 95% CI 0.84–0.88, p?<?0.0001), parity (OR?=?3.59, 95% CI 2.47–5.22, p?<?0.0001) and gestational age (OR =?1.19, 95% CI 1.07–1.32, p?= <?0.0001) but not by BMI or maternal age. The risk of cesarean section overall was significantly associated with all the variables under consideration, i.e., pre-induction cervical length (OR?=?1.09, 95% CI 1.06–1.11, p?<?0.0001), parity (OR?=?0.25, 95% CI 0.17–0.38, p?<?0.0001), BMI (OR?=?1.85, 95% CI 1.24–2.74, p?=?0.0024), gestational age (OR?=?0.88, 95% CI 0.78–0.98, p?=?0.0215) and maternal age (OR?=?1.04, 95% CI 1.01–1.07, p?=?0.0192). The risk of cesarean section for failure to progress was also significantly associated with pre-induction cervical length (OR?=?1.11, 95% CI 1.07–1.14, p?<?0.0001), parity (OR?=?0.26, 95% CI 0.15–0.43, p?<?0.0001), gestational age (OR?=?0.83, 95% CI 0.73–0.96, p?=?0.0097) and BMI (OR?=?2.07, 95% CI 1.27–3.37, p?=?0.0036).

Conclusion.?In women undergoing induction of labor, pre-induction cervical length, parity, gestational age at induction, maternal age and BMI have a significant effect on the interval between induction and delivery within 24?hours, likelihood of vaginal delivery within 24?hours and the risk of cesarean section.