Cerclage,progesterone and α-hydroxyprogeterone caproate treatment in women at risk for preterm delivery

Abstract

The most significant action of progesterone appears to be on the cervix and in prevention rather than on treatment of preterm delivery. In women with singleton gestations, no prior PTB, and CL <20?mm at <24 weeks, vaginal progesterone, either 90?mg gel or 200?mg suppository, is associated with reduction of both preterm birth (PTB) and perinatal morbidity/mortality. Cerclage is as effective as vaginal progesterone in women with CL <25?mm. Treatment of women with previous PTB with 17OHP-C from 16 to 20 weeks’ gestation until 36 weeks could reduce significantly both the risk of delivery at <37, <35 and <32 weeks’ gestation, as well as the rates of NEC, the need for supplemental oxygen and IVH. In women successfully treated with tocolytics progesterone combined with corticosteroid therapy lengthens pregnancy, reduces occurrence of respiratory distress syndrome and low birth weight. However, there is currently insufficient evidence on the role of progesterone after arrested preterm labor. It is reasonable to support an approach with CL screening of women with prior PTB starting at 16 to 19 weeks and administration of progesterone to women with a short cervix. Cerclage may be offered to those with a CL<25?mm. A combination of traditional tocolytics, corticosteroids and progesterone might be beneficial.     

The utility of screening for historical risk factors for preterm birth in women with known second trimester cervical length

Abstract

Objective: To evaluate for the presence of risk factors (RFs) for preterm birth (PTB) in women without prior PTB having second trimester cervical length (CL) screening, and to estimate the utility of RF screening.

Methods: “Low-risk” singletons were prospectively screened with midtrimester transvaginal ultrasound CL. Prior PTB, intrauterine fetal demise and lethal anomalies were excluded. Women were analyzed based on second trimester CL (<25?mm versus ≥25?mm) and the presence of RFs for PTB. A p-value of < 0.05 was considered significant.

Results: A total of 639 women were screened; 8% had CL <25?mm. Ninety-eight percent of women with CL <25?mm and 95% of women with CL ≥25?mm had RFs for PTB. Five percent of women with a CL ≥25?mm delivered preterm as compared to 18% with CL <25?mm (p?<?0.01). Treatment of cervical dysplasia, drug use during the pregnancy and unmarried status were significantly more common in women with CL <25?mm than CL ≥25?mm. When data were analyzed by CL, the presence of additional RFs did not add to the prediction of PTB <37 weeks.

Discussion: Over 95% of singleton gestations without prior PTB have ≥1 other RF for PTB. In women without prior PTB, assessment of other PTB RFs does not add to prediction of PTB provided by CL alone.     

Revisions to mid-pregnancy cervical length reference range for preterm birth screening among singleton pregnancies in Taiwan – 10 years’ experiences

ObjectiveOur study aimed to build a normal reference range for routine mid-pregnancy cervical length screening for preterm birth (PTB) based on a large cross-section of Taiwanese singleton pregnancies. Based on our reference range findings, we aim to develop a Z-score and centile calculator.Materials and methodsWe performed a retrospective analysis of the routine mid-trimester cervical length measurement in low-risk singleton pregnancies (without known abnormal growth or karyotype, congenital malformation, history of preterm birth due to preterm premature rupture of the membranes, or history of cervical cerclage treatment). From November 2008 to June 2018, the cervical lengths of 51,644 Taiwanese low-risk pregnant women were measured by experienced sonographers via transvaginal ultrasound during second trimester fetal anatomical screening at 20–24 weeks of gestation. Kolmogorov–Smirnov test was used to assess the normality of the distribution. Cole's lambda, mu, sigma (LMS) method was applied to build mid-pregnancy cervical length reference range and calculate Z-scores. Cut-off values of 2.5, 2.0 and 1.5 cm were used to evaluate the number of pregnancies considered high-risk for PTB.ResultsKolmogorov–Smirnov test showed that the cervical length measurements did not follow a normal distribution (<0.001). Reference range constructed by LMS method was presented in our study. Mean cervical length was 3.82 cm (SD = 0.62 cm). Overall, less than 0.3% of women had a cervical length shorter than 1.5 cm.ConclusionWe are providing an open access calculator for z-score and centile calculation for use in clinical practice for assessing how CL measurement compares in normally developing singleton pregnancies. Further investigation is needed to determine if Z-scores can better assess risk for PTB compared to fixed cut-offs. Since Z-scores are used to assess large deviations from normal development, they may be a useful tool for risk assessment and can be the basis for future standardized screening protocol in Taiwan.     

Amniotic fluid “sludge” is an independent risk factor for preterm delivery

Objective: To determine the prevalence and the clinical significance of amniotic fluid “sludge” (AFS) in asymptomatic patients at low and high risk for spontaneous preterm delivery.

Method: A prospective cohort study was conducted on 195 singleton pregnancies at low or high risk for preterm birth (PTB) between the 16th and 26th weeks. Cervical length (CL) <25?mm and the presence of AFS were evaluated. The risk for preterm delivery before 28, 32, 35 and 37 weeks were determined according to the presence of AFS, CL?<?25?mm and history of high risk for PTB. Stepwise logistic regression was performed to compare variables.

Results: AFS was an independent risk factor for PTB?<?35 weeks (OR: 3.08, 95% CI: 1.13–8.34, p?=?0.027) but not for PTB?<?28, 32 and 37 weeks. CL?<?25?mm was an independent risk factor for PTB?<?28, 32 and 35 but not for PTB?<?37 weeks. High risk for PTB was not found as an independent risk factor for PTB.

Conclusion: AFS is an independent risk factor for PTB before 35 weeks.     

The use of cervical length and change in cervical length for prediction of spontaneous preterm birth in asymptomatic twin pregnancies

Objective

To assess the association between cervical length (CL) and change of CL over two measurements and preterm birth (PTB) at <32 weeks in asymptomatic twin pregnancies.

Study design

This study was undertaken in the multiple pregnancy antenatal clinic at the Security Forces Hospital (SFH), a tertiary care hospital in Riyadh, Saudi Arabia, between November 2005 and October 2010. This study involved 420 women with asymptomatic twin gestations, but only 209 unselected patients completed the study and met the inclusion criteria. All patients had a CL measurement by transvaginal ultrasound at 20–23 weeks, and a second CL measurement was done within 3–5 weeks of the initial measurement. Patients were classified into two groups, group A with significant shortening of CL, and group B without significant shortening of CL. Comparisons between the groups were performed using a chi-square test or a Fisher exact test for categorical variables, whereas Student's t-test or Wilcoxon's rank-sum test was used for continuous variables. We employed ROC curves to compare the diagnostic accuracy of actual cervical length and percent change in cervical length in predicting preterm birth events. All analyses were performed using the SAS/STAT software.

Results

There were 35 (16.7%) patients whose CL shortened by ≥25% (group A), and 174 (83.3%) whose CLs either did not shorten or shortened by <25% (group B). Preterm birth at <28, <30, <32, and <34 weeks gestation was higher in group A than in group B even if the CL was >25 mm. The use of CL shortening was superior, but not statistically significantly, to the use of CL for the prediction of PTB at <32 (P = 0.0524) and <34 weeks (P = 0.281), but CL was preferred for the prediction of PTB at <28 (P = 0.037) and <30 weeks (P = 0.0457).

Conclusion

The test of two CL measurements, the first between 20 and 23 weeks gestation and another CL measurement 3–5 weeks later, with a difference of ≥25%, is a good predictor for preterm birth in asymptomatic twin pregnancies, even if the CL is >25 mm.     

Screening and prevention of preterm birth in twin pregnancies

Preterm birth (PTB) is commonest cause of perinatal mortality and morbidity in multiple pregnancies with significant long-term sequelae. The etiology of PTB is multifactorial. Universal screening by a transvaginal assessment of cervical length (CL) at midtrimester scan is recommended for all women with twin pregnancies. Women with CL ≤ 25 mm should be offered prophylactic vaginal progesterone to mitigate the risk of PTB. Other modalities like home uterine activity monitoring, digital cervical examination, fetal fibronectin (FFN) assessment, and screening for infections are not recommended. History-indicated cerclage is not advised in unselected twin pregnancies, but a combination of physical examination-indicated cerclage, tocolytics, and antibiotics may be considered in twin pregnancies with a dilated cervix prior to 24 weeks’ gestation. Routine use of cervical pessary is not advised and should be limited to research settings. Neither transvaginal CL nor FFN assessment is supported by evidence to predict the risk of PTB in symptomatic women with multiple pregnancies. More research is warranted to develop and validate algorithms to predict PTB to provide individualized care to these high-risk pregnancies.     

The effect of 17α-hydroxyprogesterone caproate on preterm birth in women with an ultrasound-indicated cerclage

We sought to determine if 17α-hydroxyprogesterone caproate (17P) reduces the rate of preterm birth (PTB) in women with an ultrasound-indicated cerclage (UIC). We retrospectively reviewed a cohort of women with a previous spontaneous PTB and current UIC placement for cervical length (CL) < 25 mm at < 23 (6)/ (7) weeks. The study group consisted of women treated with 17P; the control group consisted of women not treated with 17P. Primary outcome was spontaneous PTB < 35 weeks. Secondary outcomes included PTB < 32 weeks, PTB < 28 weeks, gestational age at delivery, and birth weight. A total of 58 women were identified; 15 (25.9%) received 17P, and 43 (74.1%) did not. 17P did not have a significant effect on PTB < 35 weeks (odds ratio 1.72, 95% confidence interval 0.50 to 5.89), nor did it have a significant effect on the secondary outcomes. Among women with a prior spontaneous PTB and current UIC for CL < 25 mm, 17P did not reduce the rate of PTB < 35 weeks.     

Cerclage for the prevention of preterm birth in high risk women receiving intramuscular 17-α-hydroxyprogesterone caproate

Objective: To assess cerclage benefit in women with short cervix also receiving 17-α-hydroxyprogesterone caproate (17P) to prevent recurrent preterm birth (PTB). Methods: Secondary analysis of a multicenter trial of ultrasound-indicated cerclage for shortened cervical length (CL). Women with prior spontaneous PTB at 16–33 6/7 weeks, singleton gestation and CL < 25?mm between 16 and 22 6/7 weeks were counseled on use of 17P and randomized to cerclage or no cerclage. Outcomes of women who received 17P were analyzed by randomization group. Primary outcome was PTB < 35 weeks. Results: 99 women received 17P: 47 cerclage; 52 no cerclage. Rates of PTB < 35 weeks were similar, 30% for cerclage and 38% for no cerclage (aOR 0.64 (0.27–1.52)). In women with CL < 15?mm, PTB < 35 weeks was reduced for the cerclage group (17% vs. 75%, p = 0.02). However, this difference was nullified after controlling for total progesterone doses received (p = 0.40). Conclusions: Cerclage was shown not to offer additional benefit for the prevention of recurrent PTB in women with short CL < 25?mm receiving 17P, but the sample size is insufficient for a definite conclusion given the 36% nonsignificant decrease in the odds of PTB < 35 weeks. Cerclage may further offer substantial benefit to women with very short CL < 15?mm and further study is needed.     

Cervical length,risk factors,and delivery outcomes among women with spontaneous preterm birth

Objectives: To evaluate differences in risk factors and delivery outcomes among women with spontaneous preterm birth (sPTB) with short (≤25?mm) versus normal (>25?mm) cervical length (CL).

Methods: Secondary analysis of a prospective cohort study of singleton gestations between 18 0/7 and 23 6/7 weeks, without prior sPTB, undergoing universal transvaginal CL screening between 1 January 2012 and 31 December 2013. Only women with sPTB (<37 0/7 weeks) were included. Demographic characteristics, risk factors for sPTB, delivery outcomes and presentation of PTB were collected. The primary outcome was mean number of risk factors.

Results: The cohort included 2071 women, of which 145 (7%) had PTB and 84 (4%) had sPTB. Sixty-nine (82%) women with sPTB had a CL >25?mm and 15 (18%) had a CL≤25?mm. Women with a short CL did not differ from women with normal CL with respect to demographic variables or mean number of risk factors (4.20?±?2.11 versus 3.52?±?1.97, p?=?0.23), but they did deliver at a significantly earlier gestational age (25.0?±?1.1 versus 34.6?±?3.1 weeks, p?<?0.01). The distribution of the presentation of sPTB was different in women with a short versus normal CL (p?<?0.01).

Conclusions: Among women with sPTB, women with a short CL had similar number of risk factors, but were more likely to deliver at a significantly earlier gestational age. A short CL identifies women at risk for very early sPTB.     

Serum decorin measurement in prediction of the risk for preterm birth

Objective

To define serum decorin (sDEC) levels in healthy pregnants and in patients with preterm labor (PTL), and to introduce possible role of sDEC in predicting the risk for preterm birth (PTB).

Analysis of pregnancy outcomes in patients undergoing ultrasound-indicated cerclage and identification the influence factors for predicting preterm birth: A retrospective study of 87 cases

ObjectiveTo investigate the factors influencing preterm birth in patients after ultrasound-indicated cerclage with different cervical lengths (CL), and explore the optimal cut-off value of CL.Materials and methodsThe retrospective study included 87 pregnant women with a history of preterm birth and second-trimester loss that received ultrasound-indicated cerclage in our hospital between January 2004 and April 2021. Groups were divided by CL at the demarcation point of 1.0, 1.5 and 2.0 cm respectively. The pregnancy outcomes were compared. Logistic regression analysis was performed to assess the independent influence factors. Receiver–operating characteristic (ROC) curves were constructed and the area under the curve (AUC) was used to compare the prediction capability of the associated factors.ResultsSignificant difference was found in terms of patients delivered at ≥32 weeks of gestation (19 [55.9%]vs. 41 [77.4%], p < 0.05) and neonatal birth weight (2495 [1138,3185]vs. 2995 [2155,3235] g, p < 0.05), when the CL was categorized at the demarcation point of 1.5 cm. Body mass index (BMI) (odds ratio [OR] = 1.224, p < 0.05), a history of preterm birth and second-trimester loss (OR = 3.153, p < 0.05), and C-reactive protein (CRP) > 5 mg/L (OR = 8.097, p < 0.05) were independent risk factors for gestational age more than 28 weeks. The AUC of joint predictor A included those factors was 0.849 (95% CI: 0.701–0.998, p < 0.05). CRP>5 mg/L was found to be a significant independent risk factor for different gestational age at delivery.ConclusionsA CL of 1.5 cm was the optimal cut-off value that could help women who underwent serial CL surveillance choose ultrasound-indicated cerclage at an appropriate time. High BMI, more history of preterm birth and second-trimester loss and abnormal CRP could be used as combined predictors to recognize the risk of preterm birth (<28 weeks) post-surgery.     

Cervicovaginal HCG and cervical length for prediction of preterm delivery in asymptomatic women at high risk for preterm delivery

Objective  To predict the risk of preterm birth (<37 weeks) or early preterm birth (<34 weeks) by cervicovaginal HCG and cervical length measured between 24–28 weeks of gestation in asymptomatic women at high risk for preterm birth. Methods  This study was conducted in the departments’ of Obstetrics & Gynaecology and Immunopathology of the Postgraduate Institute of Medical Education and Research, Chandigarh, India. In 75 pregnant women at high risk for preterm birth because of prior one on more preterm births due to spontaneous labour or ruptured membranes, cervicovaginal HCG and cervical length (by TVS) were measured between 24–28 weeks of gestation. These parameters were correlated individually and in combination for prediction of preterm birth. Results  Of the 75 women, 20 (26.7%) delivered <37 weeks and 6 (8%) delivered <34 weeks. To predict delivery <37 weeks, cervical length <2.95 cm had a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 75%, 80.1%, 71.4% and 90.7% respectively, and cervicovaginal HCG >4.75 mIU/ml had a sensitivity, specificity, PPV, and NPV of 70%, 61.81%, 40% and 85% respectively. To predict delivery <34 weeks, cervical length <2.65 cm had a sensitivity, specificity, PPV, and NPV of 50%, 85.50%, 23.08% and 95.16% respectively; and cervicovaginal HCG >14 mIU/ml had a sensitivity, specificity, PPV and NPV of 83.3%, 85.5%, 33.3% and 98.3% respectively. Cervical length was superior to predict delivery <37 weeks, whereas HCG was superior to predict delivery <34 weeks. Their combination was superior to predict preterm birth both <37 weeks or <34 weeks, than either parameter used alone. Conclusion  In high risk asymptomatic women, increased cervicovaginal HCG and reduced cervical length and between 24 to 28 weeks of gestation increased the risk of preterm delivery.     

Second trimester cervical length and risk of preterm birth in women with twin gestations treated with 17-α hydroxyprogesterone caproate

Objective.?To compare rates of preterm birth before 35 weeks based on cervical length measurement at 16–20 weeks in women with twin gestations who received 17-α hydroxyprogesterone caproate (17OHPC) or placebo.

Methods.?This is a secondary analysis of a randomised, double-blind, placebo-controlled trial of twin gestations exposed to 17OHPC or placebo. Baseline transvaginal ultrasound evaluation of cervical length was performed prior to treatment assignment at 16–20 weeks. Cervical length measurements were categorised according to the 10th, 25th, 50th and 75th percentiles in the women studied. The effect of 17OHPC administration in women with a short (25th percentile) and long (75th percentile) cervix was evaluated.

Results.?Of 661 twin gestations studied, 221 (33.4%) women enrolled at 11 centers underwent cervical length measurement. The 10th, 25th, 50th, 75th percentiles for cervical length at 16–20 weeks were 32, 36, 40 and 44?mm, respectively. The risk of preterm birth?<35 weeks was increased in women with a cervical length?<25th percentile (55.8 vs. 36.9%, p?=?0.02). However, a cervical length?>75th percentile at this gestational age interval was not protective for preterm birth (36.5 vs. 42.9%, p?=?0.42). Administration of 17OHPC did not reduce preterm birth before 35 weeks among those with either a short or a long cervix (64.3 vs. 45.8%, p?=?0.18 and 38.1 vs. 35.5%, p?=?0.85, respectively).

Conclusion.?Women with twin gestations and a cervical length below the 25th percentile at 16–20 weeks had higher rates of preterm birth. In this subgroup of women, 17 OHPC did not prevent preterm birth before 35 weeks gestation. A cervical length above the 75th percentile at 16–20 weeks did not significantly reduce the risk of preterm birth in this high risk population.     

Novel developments on cervical length screening and progesterone for preventing preterm birth

Cervical length (CL) measured by transvaginal ultrasound is an effective screening test for the prevention of preterm birth (PTB). The criteria for an effective screening test are all met by CL. It studies an important condition (PTB); it is safe and acceptable by >99% of women; it recognises an early asymptomatic phase that precedes PTB by many weeks; it has a well-described technique, is reproducible, is predictive of PTB in all populations studies so far; and, perhaps most importantly, it has been shown that 'early' treatment is effective in prevention. These two interventions, effective only in specific populations, are ultrasound-indicated cerclage and vaginal progesterone.     

Suture type and ultrasound-indicated cerclage efficacy

Objective: To assess whether type of suture material affects cerclage efficacy for preterm birth (PTB) prevention. Methods: Secondary analysis of a multicenter trial of ultrasound-indicated cerclage for short cervical length (CL), in which women with prior spontaneous PTB at 16–33 6/7 weeks, a singleton gestation and CL < 25 mm between 16–22 6/7 weeks, were randomized to McDonald cerclage or no cerclage. Outcomes of women who underwent cerclage were analyzed by type of suture material, comparing polyester braided thread (Mersilene? or Ethibond?) to Mersilene tape?. Primary outcome was PTB < 35 weeks. Results: 138 women underwent McDonald cerclage: 84 (61%) received polyester braided thread and 46 (33%) Mersilene tape?. Eight (6%) received monofilament suture and were excluded from analysis. Rates of PTB < 35 weeks were similar, 35% for polyester braided thread vs 24% for Mersilene tape? (p = .24). Birth gestational age was also similar among the 2 groups (p = .18). Conclusion: Type of suture material may not affect ultrasound-indicated cerclage efficacy in high-risk women with short CL, but further study is needed. Polyester braided thread (Mersilene? or Ethibond?) and polyester braided Mersilene tape? seem to have similar efficacy.     

Oral micronized progesterone for prevention of preterm birth

Objective

To evaluate oral micronized progesterone (OMP) to prevent preterm birth (PTB).

Methods

A randomized, double-blind, placebo-controlled trial of 150 women with at least one PTB who received 100 mg of OMP or placebo twice a day from recruitment (18-24 weeks) until 36 weeks or delivery.

Results

PTB occurred in 29 (39.2%) women in the OMP group (n = 74) compared with 44 (59.5%) in the control group (n = 74, P = 0.002). Mean gestational age at delivery was higher in the OMP group (36.1 vs 34.0 weeks, P < 0.001). Fewer preterm births occurred between 28 and 31 weeks plus 6 days in the OMP group (RR 0.20; 95% CI, 0.05-0.73, P < 0.001). Neonatal age at delivery (34 vs 32 weeks, P < 0.001), birth weight (2400 vs 1890 g, P < 0.001), NICU stay (> 24 h, P < 0.001), and Apgar scores (P < 0.001) were more favorable in the OMP group, and fewer neonatal deaths occurred (3 vs 7, P = 0.190).

Conclusion

OMP reduced the risk of PTB between 28 and 31 weeks plus 6 days, NICU admissions, and neonatal morbidity and mortality in high risk patients.     

Prediction of spontaneous preterm birth: salivary progesterone assay and transvaginal cervical length assessment after 24 weeks of gestation,another critical window of opportunity

Objectives: Measurement of salivary progesterone (SP4) levels and cervical length (CL) after 24 weeks to assess their potential predictive value among asymptomatic women at high risk of spontaneous preterm birth (PTB).

Methods: This prospective observational (noninterventional) study consecutively recruited asymptomatic women at high risk of spontaneous PTB. SP4 and CL were measured at recruitment (24–28 weeks of gestation) then repeated after 3–4 weeks. All recruited women were followed up regularly till delivery. The primary outcome measure was the occurrence of spontaneous PTB.

Results: One hundred and thirty four women completed the study, 22 (16.4%) and 32 (23.9%) women had early (<34 weeks) and late (≥34 weeks) PTB, respectively. Initially, the mean CL was 3.2?±?0.6?cm and the mean SP4 was 4062.8?±?814.6?pg/ml; with follow up, the mean CL became 3.0?±?0.6?cm and the mean SP4 became 3871.6?±?1136.9. Women with early PTB had significantly lower initial and follow up CL and SP4 measures when compared to women with late PTB and those who had birth at term. The rate of drop in SP4 and CL measurements between the two visits was also significantly higher among women with early PTB than those with late PTB and term birth. Receiver-operating characteristic (ROC) curves showed that, CL was a good predictor but SP4 was a better predictor of PTB as the area under the curve (AUC) for CL was less than that for SP4 at both visits (i.e. 0.858 and 0.868 versus 0.986 and 0.990 at the initial and follow up visits, respectively). There was a statistically significant correlation between CL and SP4 measurements. Multivariable binary logistic regression analysis revealed that follow up SP4 measurement was the only independent predictor of spontaneous PTB, and neither BMI, maternal age, SP4 nor CL were independent predictors of early spontaneous PTB.

Conclusions: After 24 gestational weeks, SP4 assessment is a simple and reliable promising tool to predict spontaneous PTB among asymptomatic high-risk women, with a little superior performance than CL measurement.     

The value of combined cervical length measurement and fetal fibronectin testing to predict spontaneous preterm birth in asymptomatic high-risk women

Objectives.?To determine the value of the combined use of fetal fibronectin (fFN) testing and transvaginal ultrasound measurement of cervical length (CL) for prediction of preterm birth (PTB) in asymptomatic high-risk women.

Methods.?One hundred and forty-seven asymptomatic women at high-risk of PTB were referred to specialist antenatal clinics and underwent CL and fFN testing over a 12-month period. Women had both tests undertaken between 22⁺⁰ and 30⁺⁰ weeks' gestation, on one or more occasions.

Results.?In those who labored spontaneously (n?=?132), positive fFN and CL?≤25?mm was associated with a 53% risk of PTB at?<37⁺⁰ weeks' gestation, compared to a 10% risk in those with a negative fFN and CL?>?25?mm. With a known CL, the addition of positive fFN yielded significant hazard ratios regardless of CL (CL?>?25 mm-HR 2.78, CL?≤25 mm-HR 3.14, p?<0.05). The hazard ratios were insignificant when CL results were added to a known fFN.

Conclusions.?In high-risk asymptomatic women, fFN may be used as a primary screening tool with CL measurement being reserved for those with a positive fFN result. Further prospective studies are needed to confirm our findings.     

Shirodkar versus McDonald cerclage for the prevention of preterm birth in women with short cervical length

The efficacy of Shirodkar cerclage was compared with that of the McDonald procedure for the prevention of preterm birth (PTB) in women with a short cervix. Secondary analysis using data from all published randomized trials including women with a short cervical length (CL) was performed comparing the use of Shirodkar versus McDonald sutures. Analysis was limited to singletons with short CL on transvaginal ultrasound. The primary outcome measure was PTB < 33 weeks. Statistical analysis was performed using bivariate and multivariable techniques. From 607 women randomly assigned in the study, 277 met our inclusion criteria; 127 received Shirodkar and 150 women received McDonald sutures. The mean ( +/- standard deviation) gestational age at delivery was 35.0 +/- 5.3 versus 36.3 +/- 4.7 for the Shirodkar versus McDonald groups, respectively ( p< 0.02). PTB < 33 weeks was seen in 61 (22%) of 277 women; 26 (20%) of 127 in the Shirodkar and 35 (23%) of 150 in the McDonald groups, respectively (odds ratio [OR], 0.85; 95% confidence interval [CI], 0.5 to 1.6). On adjusting for confounders using logistic regression modeling, no significant difference in PTB < 33 weeks was found between the two groups (OR, 0.55; 95% CI, 0.2 to 1.3). In women with short cervical length randomly assigned to receiving cerclage, no significant difference in prevention of PTB was observed using Shirodkar or McDonald's procedures.