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Mid-trimester cervical length as a risk indicator for caesarean delivery in women with a twin pregnancy
Abstract
Objective
To determine whether second‐trimester cervical length ( CL ) in women with a twin pregnancy is associated with the risk of emergency Cesarean section.
Methods
This was a secondary analysis of two randomized trials conducted in 57 hospitals in The Netherlands. We assessed the univariable association between risk indicators, including second‐trimester CL in quartiles, and emergency Cesarean delivery using a logistic regression model. For multivariable analysis, we assessed whether adjustment for other risk indicators altered the associations found in univariable (unadjusted) analysis. Separate analyses were performed for suspected fetal distress and failure to progress in labor as indications for Cesarean section.
Results
In total, 311 women with a twin pregnancy attempted vaginal delivery after 34 weeks' gestation. Emergency Cesarean delivery was performed in 111 (36%) women, of which 67 (60%) were performed owing to arrest of labor. There was no relationship between second‐trimester CL and Cesarean delivery (adjusted odds ratio ( aOR ): 0.97 for CL 26 th –50 th percentiles; 0.71 for CL 51 st – 75 th percentiles; and 0.92 for CL > 75 th percentile, using CL ≤ 25 th percentile as reference). In multivariable analysis, the only variables associated with emergency Cesarean delivery were maternal age ( aOR , 1.07 (95% CI , 1.00–1.13)), body mass index ( BMI ) ( aOR , 3.99 (95% CI , 1.07–14.9) for BMI 20–23 kg/m ² ; 5.04 (95% CI , 1.34–19.03) for BMI 24–28 kg/m ² ; and 3.1 (95% CI , 0.65–14.78) for BMI > 28 kg/m ² ) and induction of labor ( aOR , 1.92 (95% CI , 1.05–3.5)).
Conclusion
In nulliparous women with a twin pregnancy, second‐trimester CL is not associated with risk of emergency Cesarean delivery. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.
... Numerous trial of labor studies have examined the success of vaginal delivery and the rate of cesarean sections [12]; however, attempts to predict operative delivery are lacking, and studies are usually limited to the identification of risk factors in a large population or meta-analysis [5,13,14]. Several studies reported that an increased mid-trimester cervical length (CL) was associated with a higher risk of cesarean section [15][16][17][18]. Nevertheless, there are conflicting results of the association between a longer mid-trimester CL and the rate of cesarean delivery unlike the relationship between a short CL and the likelihood of preterm birth [19][20][21]. ...
... In the study, the frequency of cesarean section increased with odds of 20.3% for every additional centimeter of CL. Van de Mheen et al. [17] performed a similar study on twin pregnancy; however, the mid-trimester CL was not associated with a risk of cesarean section. Unlike that study, Sung et al. [16] reported that a longer CL in mid-pregnancy was a risk factor for cesarean section in twins and higher rates of cesarean deliveries as the quartiles of the study population increased. ...
Objective:
This study aimed to evaluate whether an increased cervical length (CL) measured in the mid-trimester is associated with vacuum-assisted vaginal delivery.
Methods:
This retrospective cohort study included women who delivered vaginally in Seoul National University Bundang Hospital (n=820) and Boramae Medical Center (n=509) between January 2017 and February 2019. Multifetal pregnancies and preterm births before 37 weeks of gestation were excluded. Only those cases in which CL was measured at 18-22 weeks of gestation for the purpose of screening for preterm birth risk in each institution were analyzed (n=537). Other significant risk factors were reviewed.
Results:
The median gestational age at delivery was 39.4 weeks (range, 37.0-41.6 weeks); 18.6% (100/537) were vacuum-assisted delivery. There was no relationship between mid-trimester CL and vacuum-assisted delivery (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.57-1.62), while nulliparity was associated with a higher risk (OR, 3.64; 95% CI, 1.55-8.57) than multiparity. When the population was divided into 3 groups by CL range, vacuum-assisted delivery rates increased as CL length increased in nulliparous women.
Conclusion:
Mid-trimester CL did not predict the need for vacuum-assisted vaginal delivery.
Objective:
It is well known that a short cervix at mid-pregnancy is a risk factor for spontaneous preterm birth in both singleton and twin gestations. Recent evidence also suggests that a long cervix at mid-pregnancy is a predictor of the risk of cesarean section (C/S) in singleton gestation. The purpose of this study was to determine whether a long cervix at mid-pregnancy was associated with an increased risk of C/S in women with twin pregnancies.
Methods:
We enrolled 746 women pregnant with twins whose cervical length was measured by trans-vaginal ultrasonography at a mean of 22 weeks of gestation and who delivered in our institution. Cases with a short cervix [cervical length (CL) <15 mm] were excluded. Cases were divided into four groups according to the quartile of CL.
Results:
The rate of C/S increased according to the quartile of CL (47% in the 1st quartile, 51% in the 2nd quartile, 56% in the 3rd quartile and 62% in the 4th quartile, P<0.005, χ2 for trend). CL was an independent risk factor for C/S even after adjustment for confounding variables. When confining analysis to women who delivered after a trial of labor (n=418), to nulliparous women (n=633) or to those who delivered at late preterm or full term (n=666), the rate of C/S also increased according to the quartile of CL, and the relationship between CL and the risk of C/S remained significant after adjustment in each group.
Conclusion:
In women pregnant with twins, long CL at mid-pregnancy was a risk factor for C/S.
Background Twin birth is associated with a higher risk of adverse perinatal outcomes than singleton birth. It is unclear whether planned cesarean section results in a lower risk of adverse outcomes than planned vaginal delivery in twin pregnancy. Methods We randomly assigned women between 32 weeks 0 days and 38 weeks 6 days of gestation with twin pregnancy and with the first twin in the cephalic presentation to planned cesarean section or planned vaginal delivery with cesarean only if indicated. Elective delivery was planned between 37 weeks 5 days and 38 weeks 6 days of gestation. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity, with the fetus or infant as the unit of analysis for the statistical comparison. Results A total of 1398 women (2795 fetuses) were randomly assigned to planned cesarean delivery and 1406 women (2812 fetuses) to planned vaginal delivery. The rate of cesarean delivery was 90.7% in the planned-cesarean-delivery group and 43.8% in the planned-vaginal-delivery group. Women in the planned-cesarean-delivery group delivered earlier than did those in the planned-vaginal-delivery group (mean number of days from randomization to delivery, 12.4 vs. 13.3; P=0.04). There was no significant difference in the composite primary outcome between the planned-cesarean-delivery group and the planned-vaginal-delivery group (2.2% and 1.9%, respectively; odds ratio with planned cesarean delivery, 1.16; 95% confidence interval, 0.77 to 1.74; P=0.49). Conclusions In twin pregnancy between 32 weeks 0 days and 38 weeks 6 days of gestation, with the first twin in the cephalic presentation, planned cesarean delivery did not significantly decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00187369 ; Current Controlled Trials number, ISRCTN74420086 .).
To assess neonatal and maternal morbidity in twins ≥ 32 weeks' gestation, related to the changes in planned mode of delivery, a retrospective cohort study was performed, including 185 twin births delivered in the Atrium Medical Centre, Heerlen, during the years 2003-2008. The results were compared with those of an earlier study from our department during the period 1999-2002. Compared with the 1999-2002 cohort, the elective caesarean section rate significantly increased from 17.7% to 36.8%. The secondary caesarean rate significantly decreased from 15.9% to 8.8%, but increased from 1.2% to 3.3% for only twin B. No significant differences in serious neonatal morbidity rates for twins A and B were found between both study periods, neither in the elective caesarean group, nor in the planned vaginal birth group. Serious maternal morbidity was not significantly increased in both groups compared with the 1999-2002 cohort.
We undertook a systematic review and meta-analysis to determine whether a policy of planned cesarean section or vaginal delivery is better for twins.
We searched MEDLINE and EMBASE from 1980 through May 2001 using combinations of the following terms: twin, delivery, cesarean section, vaginal birth, birth weight, and gestational age. Studies that compared planned cesarean section to planned vaginal birth for babies weighing at least 1500 g or reaching at least 32 weeks' gestation were included. We computed pooled odds ratios for perinatal or neonatal mortality, low 5-minute Apgar score, neonatal morbidity, and maternal morbidity. The infant was the unit of statistical analysis. Results were considered statistically significant if the 95% CI did not encompass 1.0.
We retrieved 67 articles, 63 of which were excluded. Four studies with a total of 1932 infants were included in the analysis. A low 5-minute Apgar score occurred less frequently in twins delivered by planned cesarean section (odds ratio, 0.47; 95% CI, 0.26-0.88) principally because of a reduction among twins if twin A was in breech position (odds ratio, 0.33; 95% CI, 0.17-0.65). Twins delivered by planned cesarean section spent significantly longer in the hospital (mean difference, 4.01 days; 95% CI, 0.73-7.28 days). There were no significant differences in perinatal or neonatal mortality, neonatal morbidity, or maternal morbidity.
Planned cesarean section may decrease the risk of a low 5-minute Apgar score, particularly if twin A is breech. Otherwise, there is no evidence to support planned cesarean section for twins.
In most situations, simple techniques for handling missing data (such as complete case analysis, overall mean imputation, and the missing-indicator method) produce biased results, whereas imputation techniques yield valid results without complicating the analysis once the imputations are carried out. Imputation techniques are based on the idea that any subject in a study sample can be replaced by a new randomly chosen subject from the same source population. Imputation of missing data on a variable is replacing that missing by a value that is drawn from an estimate of the distribution of this variable. In single imputation, only one estimate is used. In multiple imputation, various estimates are used, reflecting the uncertainty in the estimation of this distribution. Under the general conditions of so-called missing at random and missing completely at random, both single and multiple imputations result in unbiased estimates of study associations. But single imputation results in too small estimated standard errors, whereas multiple imputation results in correctly estimated standard errors and confidence intervals. In this article we explain why all this is the case, and use a simple simulation study to demonstrate our explanations. We also explain and illustrate why two frequently used methods to handle missing data, i.e., overall mean imputation and the missing-indicator method, almost always result in biased estimates.
Background:
Twin birth is associated with a higher risk of adverse perinatal outcomes than singleton birth. It is unclear whether planned cesarean section results in a lower risk of adverse outcomes than planned vaginal delivery in twin pregnancy.
Methods:
We randomly assigned women between 32 weeks 0 days and 38 weeks 6 days of gestation with twin pregnancy and with the first twin in the cephalic presentation to planned cesarean section or planned vaginal delivery with cesarean only if indicated. Elective delivery was planned between 37 weeks 5 days and 38 weeks 6 days of gestation. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity, with the fetus or infant as the unit of analysis for the statistical comparison.
Results:
A total of 1398 women (2795 fetuses) were randomly assigned to planned cesarean delivery and 1406 women (2812 fetuses) to planned vaginal delivery. The rate of cesarean delivery was 90.7% in the planned-cesarean-delivery group and 43.8% in the planned-vaginal-delivery group. Women in the planned-cesarean-delivery group delivered earlier than did those in the planned-vaginal-delivery group (mean number of days from randomization to delivery, 12.4 vs. 13.3; P=0.04). There was no significant difference in the composite primary outcome between the planned-cesarean-delivery group and the planned-vaginal-delivery group (2.2% and 1.9%, respectively; odds ratio with planned cesarean delivery, 1.16; 95% confidence interval, 0.77 to 1.74; P=0.49).
Conclusions:
In twin pregnancy between 32 weeks 0 days and 38 weeks 6 days of gestation, with the first twin in the cephalic presentation, planned cesarean delivery did not significantly decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00187369; Current Controlled Trials number, ISRCTN74420086.).
To evaluate whether an increased ultrasonographic cervical length in the second trimester is associated with an increased frequency of cesarean delivery.
This is a retrospective cohort study of nulliparous women with a singleton pregnancy who underwent routine cervical length screening between 16 and 24 weeks of gestation and labored after 34 weeks of gestation at a single tertiary care hospital. Women were grouped by cervical length quartile, and the association between cervical length quartile and cesarean delivery was determined in both univariable and multivariable analyses.
For every additional centimeter of cervical length, the odds of cesarean delivery increased by 20.3%. Similarly, the frequency of cesarean delivery increased with increasing second-trimester cervical length quartiles (17.4%, 22.3%, 21.8%, 27.7%; P<.001). This association persisted in multivariable analyses that included gestational age at delivery and induction of labor. This increased risk of cesarean delivery was primarily the result of women with arrest disorders in the first stage of labor (P<.001).
Increased second-trimester cervical length quartile is associated with an increased frequency of primary cesarean delivery in nulliparous women. LEVEL OF EVIDENCE:: II.
In women with a multiple pregnancy, spontaneous preterm delivery is the leading cause of perinatal morbidity and mortality. Interventions to reduce preterm birth in these women have not been successful. We assessed whether a cervical pessary could effectively prevent poor perinatal outcomes.
We undertook a multicentre, open-label randomised controlled trial in 40 hospitals in the Netherlands. We randomly assigned women with a multiple pregnancy between 12 and 20 weeks' gestation (1:1) to pessary or control groups, using a web-based application with a computer-generated list with random block sizes of two to four, stratified by hospital. Participants and investigators were aware of group allocation. For women in the pessary group, a midwife or obstetrician inserted a cervical pessary between 16 and 20 weeks' gestation. Women in the control group did not receive the pessary, but otherwise received similar obstetrical care to those in the pessary group. The primary outcome was a composite of poor perinatal outcome: stillbirth, periventricular leucomalacia, severe respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular haemorrhage, necrotising enterocolitis, proven sepsis, and neonatal death. Analyses were by modified intention to treat. This trial is registered in the Dutch trial registry, number NTR1858.
Between Sept 21, 2009, and March 9, 2012, 813 women underwent randomisation, of whom 808 were analysed (401 in the pessary group; 407 in the control group). At least one child of 53 women (13%) in the pessary group had poor perinatal outcome, compared with 55 (14%) in the control group (relative risk 0·98, 95% CI 0·69-1·39).
In unselected women with a multiple pregnancy, prophylactic use of a cervical pessary does not reduce poor perinatal outcome.
The Netherlands Organisation for Health Research and Development.
Objectives
To estimate the association between the cervical length (CL) measurement at 30–32 weeks and the mode of delivery in twin pregnancies.Methods
This was a retrospective study of a cohort, from 2005–2010, of 265 twin pregnancies with a CL measurement at 30–32 weeks. We compared the CL measurement at 30–32 weeks based on mode of delivery. We then analyzed our data across four subgroups, based on the CL measurement quartiles at 30–32 weeks. We performed this analysis in all patients, and also performed a planned subgroup analysis of 130 patients who attempted a vaginal delivery.ResultsIn all patients, including those who attempted a vaginal delivery, the mean CL at 30–32 weeks was significantly shorter in women who delivered vaginally compared with women who had a Cesarean section. The likelihood of Cesarean delivery increased significantly with increasing CL measurement across the groups defined by measurement quartiles. On adjusted analysis controlling for maternal age, race, in-vitro fertilization, chorionicity, induction of labor and prior vaginal delivery, the CL measurement at 30–32 weeks was independently associated with mode of delivery.Conclusions
In twin pregnancies, the CL at 30–32 weeks is significantly associated with the likelihood of Cesarean delivery. A longer CL may represent underdevelopment of the uterus, leading to a higher risk of Cesarean delivery in labor at term. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Twin pregnancies are associated with increased perinatal mortality, mainly related to prematurity, but complications during birth may contribute to perinatal loss or morbidity. The option of planned caesarean section to avoid such complications must therefore be considered. On the other hand, randomised trials of other clinical interventions in the birth process to avoid problems related to labour and birth (planned caesarean section for breech, and continuous electronic fetal heart rate monitoring), have shown an unexpected discordance between short-term perinatal morbidity and long-term neurological outcome. The risks of caesarean section for the mother in the current and subsequent pregnancies must also be taken into account.
To determine the short- and long-term effects on mothers and their babies, of planned caesarean section for twin pregnancy.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2011).
Randomised trials comparing a policy of caesarean section with planned vaginal birth for women with twin pregnancy.
Two researchers independently assessed eligibility, quality and extracted data. Data were checked for accuracy.
One small trial with unconfirmed allocation concealment compared caesarean section with planned vaginal birth in 60 women with vertex/non-vertex twin pregnancies. There were no differences in perinatal outcome. The trial was too small to exclude the possibility of clinically meaningful benefits of either approach. There is one additional trial currently ongoing.
There is a lack of robust evidence to guide clinical advice regarding the method of birth for twin pregnancies. Women should be informed of possible benefits and risks of either approach, including short-term and long-term consequences for both mother and babies. Future research should aim to provide unbiased evidence, including long-term outcomes.
To estimate whether administration of 17α-hydroxyprogesterone caproate can prevent neonatal morbidity in multiple pregnancies by reducing the preterm birth rate.
We conducted a multicenter, double-blind, placebo-controlled randomized trial in 55 obstetric clinics in the Netherlands. Women with a multiple pregnancy were randomized to weekly injections of either 250 mg 17α-hydroxyprogesterone caproate or placebo, starting between 16 and 20 weeks of gestation and continuing until 36 weeks of gestation. The main outcome measure was adverse neonatal outcome. Secondary outcome measures were gestational age at delivery and delivery before 28, 32, and 37 weeks of gestation.
We randomized 671 women. A composite measure of adverse neonatal outcome was present in 110 children (16%) born to mothers in the 17α-hydroxyprogesterone caproate group, and in 80 children (12%) of mothers in the placebo group (relative risk [RR] 1.34; 95% confidence interval [CI] 0.95-1.89). The mean gestational age at delivery was 35.4 weeks for the 17α-hydroxyprogesterone caproate group and 35.7 weeks for the placebo group (P=.32). Treatment with 17α-hydroxyprogesterone caproate did not reduce the delivery rate before 28 weeks (6% in the 17α-hydroxyprogesterone caproate group compared with 5% in the placebo group, RR 1.04; 95% CI 0.56-1.94), 32 weeks (14% compared with 10%, RR 1.37; 95% CI 0.91-2.05), or 37 weeks of gestation (55% compared with 50%, RR 1.11; 95% CI 0.97-1.28).
17α-hydroxyprogesterone caproate does not prevent neonatal morbidity or preterm birth in multiple pregnancies.
ISRCTN Register, www.isrctn.org, ISRCTN40512715.
To review the literature on cervical length as a predictor of preterm birth in asymptomatic women with a multiple pregnancy.
We searched MEDLINE, Embase and reference lists of included articles to identify all studies that reported on the accuracy of cervical length for predicting preterm birth in asymptomatic women with a multiple pregnancy. We scored study characteristics and study quality, and extracted data in order to construct two-by-two tables cross-classifying cervical length and preterm delivery. Meta-analysis using a bivariate model was performed. Summary receiver-operating characteristics (ROC) curves were generated for various test characteristics and outcome definitions.
We found 21 studies reporting on 2757 women. There was a large variation in gestational age at measurement, cut-off point for cervical length and definition of preterm birth. The summary ROC curve indicated a good predictive capacity of short cervical length for preterm birth. Summary estimates of sensitivity and specificity for preterm birth before 34 weeks' gestation were 78% and 66%, respectively, for 35 mm, 41% and 87% for 30 mm, 36% and 94% for 25 mm and 30% and 94% for 20 mm.
In women with a multiple pregnancy, second-trimester cervical length is a strong predictor of preterm birth. In the absence of effective preventive strategies, there is currently no place in clinical practice for cervical length measurement in this population. However, future studies should evaluate preventive interventions in women with multiple pregnancies and a short cervix, and cervical length should be measured in any trial studying preventive strategies in multiple pregnancies.
To assess the accuracy of transvaginal sonographic cervical length (CL) in predicting spontaneous preterm birth in women with twin pregnancies.
Systematic review and metaanalysis of predictive test accuracy.
Twenty-one studies (16 in asymptomatic women and 5 in symptomatic women) with a total of 3523 women met the inclusion criteria. Among asymptomatic women, a CL <or=20 mm at 20-24 weeks' gestation was the most accurate in predicting preterm birth <32 and <34 weeks' gestation (pooled sensitivities, specificities, and positive and negative likelihood ratios of 39% and 29%, 96% and 97%, 10.1 and 9.0, and 0.64 and 0.74, respectively). A CL <or=25 mm at 20-24 weeks' gestation had a pooled positive likelihood ratio of 9.6 to predict preterm birth <28 weeks' gestation. The predictive accuracy of CL for preterm birth was low in symptomatic women.
Transvaginal sonographic CL at 20-24 weeks' gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies.
Introduction General Conditions for the Randomization-Validity of Infinite-m Repeated-Imputation Inferences Examples of Proper and Improper Imputation Methods in a Simple Case with Ignorable Nonresponse Further Discussion of Proper Imputation Methods The Asymptotic Distribution of (Q̄m, Ūm, Bm) for Proper Imputation Methods Evaluations of Finite-m Inferences with Scalar Estimands Evaluation of Significance Levels from the Moment-Based Statistics Dm and Δm with Multicomponent Estimands Evaluation of Significance Levels Based on Repeated Significance Levels
The cervix has to open to allow vaginal birth. Ultrasound has now shown that this lower part of the uterus begins to show changes weeks before eventual birth. Only transvaginal ultrasound should be used to evaluate the cervix for prediction of preterm birth (PTB). The shortest best cervical length (CL) is the most effective measurement for clinical use. Proper technique is paramount for accurate results. The risk of PTB increases with ever shorter CL (<25 mm). Other factors that must be carefully considered when using CL for prediction of PTB are number of fetuses, risk factors for PTB, and gestational age at screening.
We evaluated the risk factors associated with cesarean delivery in laboring twin gestations at least 36 completed weeks.
We reviewed the records of 134 women with twin gestations who underwent a trial of labor between 1993 and 1995. Women who delivered by cesarean were compared with women who delivered vaginally. The factors associated with an increased risk for cesarean were determined using univariate analysis. Logistic regression was used to determine which of those factors was most strongly associated with cesarean delivery.
Of 134 laboring twin gestations, 25 (18.7%) delivered by cesarean and 109 (81.3%) delivered vaginally. Univariate analysis revealed that women who delivered by cesarean were more likely to be nulliparous, have a less advanced cervix at both admission and epidural placement, a higher mean oxytocin infusion rate for induction or augmentation of labor, a combined fetal weight greater than 5500 g, and received magnesium for seizure prophylaxis. Multivariate analysis identified that nulliparity and timing of epidural administration were the factors most strongly associated with cesarean delivery.
The timing of epidural analgesia is a modifiable risk factor strongly associated with cesarean delivery in term and near-term laboring twin gestations.
To establish the relation between cervical length at 23 weeks of gestation in twin pregnancies and risk of spontaneous delivery before 33 weeks.
Cervical length was measured by transvaginal sonography at 23 (range 22-24) weeks of gestation in 464 twin pregnancies attending for routine antenatal care. In the patients who were managed expectantly the relation between cervical length and the rate of spontaneous delivery before 33 weeks was determined.
The cervical length distribution was skewed to the left and the median value was 36 mm. The rate of spontaneous delivery before 33 weeks was inversely related to cervical length at 23 weeks. It increased gradually from about 2.5% at 60 mm, to 5% at 40 mm and 12% at 25 mm, and exponentially below this length to 17% at 20 mm and 80% at 8 mm. Cervical length of 20 mm or less is found in about 8% of the population and this group contained about 40% of women delivering spontaneously before 33 weeks.
In twin pregnancies measurement of cervical length provides useful prediction of risk for spontaneous early preterm delivery.
To determine a possible relationship between neonatal and maternal outcomes in twin gestations and the planned mode of delivery.
A single-centre retrospective cohort study in twins > or =32 weeks of gestational age was performed. Baseline characteristics, and neonatal and maternal outcomes were documented according to the planned mode of delivery: a planned caesarean section or a planned vaginal birth. Statistical analysis was performed using chi-square test. Fisher exact test was used in case correction was needed.
During the study period (1999-2002), 164 twins > or =32 weeks were enrolled in the study. In 29 women (17.7%) an elective caesarean section was performed. The remaining 135 twins (82.3%) were allowed to start a vaginal delivery. An emergency or an urgent secondary caesarean section for both twins was performed in 26 women, and in 2 women for twin B only. One twin B baby died during planned vaginal delivery. No significant differences in perinatal mortality and serious neonatal morbidity were found between both groups (10.3% versus 9.6%). Neonatal outcomes in twins A were significantly better than in twins B (2.4% versus 7.3%), independent of the planned mode of delivery. Serious maternal morbidity was not significantly different between both groups (13.8% versus 19.3%), although 2 women in the elective caesarean section group needed a relaparotomy for haemorrhage.
Our results do not support an elective caesarean section for twin gestations > or =32 weeks. The success rate of vaginal delivery in the planned vaginal birth group was nearly 80%.
Physiological and biochemical studies suggest that normal parturition at term is dependent on programmed development of the uterus in early pregnancy. It is recognized that a short cervix in mid-pregnancy is associated with an increased risk of spontaneous preterm birth. We hypothesized that a long cervix in mid-pregnancy would be associated with an increased risk of cesarean delivery during labor at term.
We studied 27,472 primiparous women who had a cervical length of 16 mm or more at a median of 23 weeks of gestation and who ultimately delivered a live infant in labor at term.
The rate of cesarean delivery at term was lowest (16.0%) among women with a mid-pregnancy cervical length in the lowest quartile (16 to 30 mm) and was significantly greater in the second quartile (18.4%, 31 to 35 mm), third quartile (21.7%, 36 to 39 mm), and fourth quartile (25.7%, 40 to 67 mm) (P<0.001 for trend). The odds ratio for cesarean delivery among women in the fourth quartile, as compared with the first quartile, was 1.81 (95% confidence interval [CI], 1.66 to 1.97), and the odds ratio adjusted for maternal age, body-mass index, smoking status, race or ethnic group, gestational age at birth, spontaneous or induced labor, birth-weight percentile, and hospital of delivery was 1.68 (95% CI, 1.53 to 1.84; P<0.001). The increased risk of cesarean delivery was attributable to procedures performed for poor progress in labor.
The cervical length at mid-pregnancy is an independent predictor of the risk of cesarean delivery at term in primiparous women.
Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pregnancies: a systematic review and meta-analysis
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