Normal Cervical Length Research Articles

463: Second trimester normal cervical length in asymptomatic high-risk women: Role of the cervical consistency index

463: Second trimester normal cervical length in asymptomatic high-risk women: Role of the cervical consistency index

Cervical consistency index is a valid predictor of preterm birth in low-risk pregnant women

Background Preterm birth (PTB) remains a global problem associated with perinatal morbidity, including low birth weight, growth retardation and irreversible damage to the nervous system. The objective of this study was to determine the predictive value of cervical consistency index (CCI) to indicate the occurrence of PTB in mid trimester screening of low risk pregnant women. MethodsThis was a prospective study conducted on low-risk pregnant women at 14-28 weeks of pregnancy. The cervical length (CL) and AP cervical diameter were measured and the CCI determined according to the formula AP2/AP1*100. The ROC curves were drawn according to gestational age and the sensitivity and the specificity were calculated for optimal cut-off for 1st, 5th, 10th, 21th, and 24th centiles of CCI. The inter-observer agreement was validated by interclass correlation coefficients (ICC).ResultsA total of 149 participants were enrolled in this study. Among them, 12.08% had PTB (<37weeks) and 87.92% had normal birth. Mean CCI for all subjects was 68.60%, but was lower in PTB (48.9%). The best cutoff for predicting PTB based on CCI was 59.46% with 99.18% sensitivity and 85% specificity. The AUC for CCI for prediction of PTB <37weeks was 0.936. There was no inter-observer difference in measurement of CCI and CL (ICC values for CCI and CL were 0.997 and 0.990 respectively).ConclusionIn women with normal CL the CCI could predict PTB in the second trimester in low risk women. So, CCI is a valid predictor of PTB in low risk women.

Neutrophil elastase in cervical fluid in women with short cervical length

ObjectiveThe aim of the study was to determine the relationships between short cervical length (CL) and levels of cervical fluid neutrophil elastase (NE), secretory leukocyte protease inhibitor (SLPI), and interleukin 8 (IL-8) in the second trimester of pregnancy of women who underwent ultrasound-indicated cervical cerclage. Materials and methodsCL of <25 mm or cervical funneling were included in the short CL group (n = 26) and the normal CL group (n = 22) included women who had CL of ≥25 mm and had no cervical funneling in women between 17 + 0 and 24 + 6 weeks of gestation. Levels of NE, SLPI, and IL-8 were measured by using enzyme-linked immunosorbent assay kits. Mann–Whitney U tests and Spearman's correlation analysis were used for statistical analyses. ResultsCompared with the normal CL group, the short CL group had significantly higher median NE levels (P < 0.001) and higher, though not significant, median IL-8 levels by approximately three times (2107.0 vs. 798.3 pg/mL, P = 0.132). The median SLPI levels in cervical fluid was similar between the two groups (107.6 vs. 103.2 ng/mL, P = 0.499). Short CL had a significant correlations with cervical fluid NE levels (r = −0.475, P = 0.001). ConclusionIncreased cervical fluid NE associated with cervical shortening in second trimester of pregnancy, whereas cervical fluid SLPI had constant levels.

A soft cervix, categorized by shear-wave elastography, in women with short or with normal cervical length at 18-24 weeks is associated with a higher prevalence of spontaneous preterm delivery.

To determine whether a soft cervix identified by shear-wave elastography between 18 and 24 weeks of gestation is associated with increased frequency of spontaneous preterm delivery (sPTD). This prospective cohort study included 628 consecutive women with a singleton pregnancy. Cervical length (mm) and softness [shear-wave speed: (SWS) meters per second (m/s)] of the internal cervical os were measured at 18-24 weeks of gestation. Frequency of sPTD <37 (sPTD<37) and <34 (sPTD<34) weeks of gestation was compared among women with and without a short (≤25 mm) and/or a soft cervix (SWS <25th percentile). There were 31/628 (4.9%) sPTD<37 and 12/628 (1.9%) sPTD<34 deliveries. The combination of a soft and a short cervix increased the risk of sPTD<37 by 18-fold [relative risk (RR) 18.0 (95% confidence interval [CI], 7.7-43.9); P<0.0001] and the risk of sPTD<34 by 120-fold [RR 120.0 (95% CI 12.3-1009.9); P<0.0001] compared to women with normal cervical length. A soft-only cervix increased the risk of sPTD<37 by 4.5-fold [RR 4.5 (95% CI 2.1-9.8); P=0.0002] and of sPTD<34 by 21-fold [RR 21.0 (95% CI 2.6-169.3); P=0.0003] compared to a non-soft cervix. A soft cervix at 18-24 weeks of gestation increases the risk of sPTD <37 and <34 weeks of gestation independently of cervical length.

The Utility of Transvaginal Cervical Length in Predicting Delivery Interval in Viable Outpatient Twin Pregnancies [27P

INTRODUCTION: Predicting preterm delivery in twin gestations helps identify women who may benefit from interventions such as antenatal corticosteroids within 7 days of delivery. Our aim was to quantify the performance of short cervical length (CL) (&lt;25mm) in outpatient twin gestations to predict delivery within 7 days. METHODS: Outpatient transvaginal ultrasound reports for diamniotic twin gestations of 23w 0d to 28w 6sd were reviewed between January 2010-July 2014. Index CL was defined as the first CL less than 25mm. Primary outcome was the positive predictive value (PPV) of spontaneous delivery within 7 days of index CL. Secondary outcomes included PPV of index CL of 15mm and 10mm. RESULTS: Of the 411 included charts, 52 patients (12.6%) had a short cervix. There were no significant differences in major risk factors for preterm birth. Four women (1% of the total study population) delivered within 7 days of index CL; three of these had a short cervix while one had a normal CL. PPV of 25mm CL was 5.8% (95% CI 1.2-16.0); NPV 99.7% (95% CI 98.5- &gt;99.9). The PPV of 15mm and 10mm CL were 9.1% (95% CI 1.1-29.2) and 20.0% (95% CI 7.5-55.6). CONCLUSION: In this retrospective observational study, CL of less than 25mm had a poor positive predictive value for delivery within 7 days. 25mm CL cutoff may not be useful to time interventions such as betamethasone administration or hospitalization. PPV increases with decreasing CL. Other tools can be considered in addition to CL measurement for intervention.

430: Cervical length shortening between pregnancies and preterm delivery

To test whether a decrease in midtrimester cervical length between pregnancies is associated with preterm delivery in a subsequent pregnancy. This is a cohort study of women who had two consecutive singleton births of at least 20 weeks’ gestation at one institution who had a midtrimester cervical length measured in each pregnancy. Cervical length change between pregnancies was measured as the difference in centimeters (cm) between cervical lengths using the measurement taken closest to 20 weeks 0 days’ gestation in each pregnancy. Cervical length shortening was defined as present if the cervical length decreased by one standard deviation or more between index and subsequent pregnancies. Bivariable analyses and multivariable logistic regression were used to determine whether cervical length shortening between pregnancies was associated with preterm delivery. Breslow-Day tests for homogeneity were used to assess for differences in the odds of preterm birth after stratification by preterm birth in the index pregnancy or a short cervix (< 2.5 cm) in the subsequent pregnancy. Among the 1,693 women who met inclusion criteria, mean change in midtrimester cervical length between pregnancies was -0.1 ± 0.9 cm; 130 (7.7%) experienced a preterm delivery in the subsequent pregnancy. Compared to women whose subsequent pregnancy cervical length remained stable or increased, women whose cervical length shortened were more likely to experience a preterm delivery (11.5% vs 6.8%, p=0.006). In the multivariable model, cervical length shortening remained significantly associated with preterm delivery even when accounting for interdelivery interval, cervical length in the subsequent pregnancy, or a preterm delivery or short cervix in the index pregnancy (Table). The magnitude of the increased risk in preterm birth did not significantly differ between women with a most recent preterm vs term birth (p-value for Breslow-Day = 0.07) or between women with a normal vs short cervical length in the subsequent pregnancy (p-value for Breslow-Day = 0.64). Midtrimester cervical length shortening between pregnancies is independently associated with an increased risk of preterm delivery. The increased risk for preterm birth associated with cervical length shortening was similar in women with a most recent term birth and in women with a normal cervical length in the subsequent pregnancy.

ROLE OF BIOCHEMICAL MARKERS AND TRANSVAGINAL ULTRASOUND IN THE PREDICTION OF PRETERM LABOR

Background : Evaluation of cervicovaginal fetal fibronectin was considered as one of the most predictive factor for preterm labor when it is 50 ng/ml. Also, Salivary estriol (E3) has the same predictive factor for preterm labor when it is over 2.1ng/ml. The last factor in this study was measurement of cervical length. Objective: Assessing cervicovaginal fetal fibronectin and maternal Salivary estriol (E3) as biochemical markers, as well as transvaginal ultrasound in the prediction of preterm labor. Patients and Methods: The study included 150 pregnant women at gestational ages between 24 weeks and 34 weeks confirmed by sure history of last menstrual period and first trimestric ultrasound examination.The patients in this study were fulfilling the inclusion criteria, and were enlisted in a prospective clinical trial. As regard cervicovaginal fetal fibronectin, measure of it as Dacron swab was rotated in posterior fornix of the vagina or ectocervix and sent for assay of fetal fibronectin. Salivary estriol (E3) was collected from mouth after washing it, and stored till time of assay. Cervical length was evaluated by transvaginal ultrasound. Results: There was a highly significant difference between women with positive and negative fibronectin regarding gestational age at delivery. Salivary estriol (E3) showed a highly significant difference between women with positive and negative E3 regarding gestational age at delivery. Also, cervical length showed a highly significant difference between women with short and normal cervical length regarding gestational age at delivery. There was no significant effect for age, parity, presence of uterine contractions and uterine anomalies on the outcome of pregnancy . Conclusion: Cervicovaginal fetal fibronectin, salivary estriol E3 and measurement of cervical length were more helpful in prediction of preterm labor.

711: Predicting recurrent spontaneous preterm birth in women with normal mid-trimester cervical length

Spontaneous preterm birth (SPTB) remains the leading cause of morbidity and mortality among non-anomalous infants. Though a prior SPTB is the greatest risk factor for recurrence, and risk increases substantially with short cervical length (CL, <2.50cm), pregnancy outcomes are less certain among those with a normal CL. We sought to characterize risk factors for recurrent PTB in women with a normal mid-trimester CL. This is a secondary analysis of two prospective, multicenter studies that enrolled women with singleton gestations and ≥1 prior SPTB 15-36 weeks; study #1 was observational and study #2 was a RCT with negative findings (intervention did not impact SPTB rate). We included women with ≥ 1 vaginal CL 15.0-24.0 weeks’ with a shortest CL ≥ 25mm. We excluded those whose neonates were diagnosed with a major congenital anomaly postnatally. Women with recurrent PTB <37.0 weeks were compared to those delivering at term. Data were analyzed with chi-square, fisher’s exact, t-test, and stepwise backwards elimination logistic regression as appropriate. Of 521 women with ≥ 1 CL, 451 (87%) had a shortest CL ≥25mm and were included. Of these, 163 (35%) delivered preterm (median 34.4, IQR 31.0-36.0 weeks), and 288 (65%) delivered at term (median 38.9, IQR 37.9-39.7 weeks). Further, 72 (16%) delivered <32 weeks, including 29 (6%) <28 weeks. Demographic and baseline characteristics of those with PTB and term delivery are shown in Table 1. Those destined to have recurrent PTB had shorter ‘shortest’ CL [median 34mm (IQR 31,40) vs. 37mm (IQR 33,41) but were not more likely to have a shortest CL measuring 25-29mm (14% vs. 13%). The cervical length was measured at a median 18.6 (IQR 17.4, 20.4) weeks, and 9 women had a cerclage placed; these were similar in PTB and term births. Those with recurrent PTB were more likely to develop a placental abruption (9% vs. 3%, p=0.003). In multivariable models, several factors remained associated with recurrent PTB <37 weeks’ gestation (Table 2). The majority of women with a previous SPTB have a normal CL ≥25mm in the mid-trimester. Despite this, they remain at high risk for recurrent SPTB. Clinicians should remain vigilant when caring for women with a prior SPTB, even when the cervical length exceeds current intervention thresholds.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Follow-Up of Asymptomatic High-Risk Patients with Normal Cervical Length to Predict Recurrence of Preterm Birth

Background: A midtrimester cervical length (CL) <25 mm is associated with spontaneous preterm birth (sPTB). However, as CL ≥25 mm is not enough to exclude recurrence in high-risk patients, follow-up CL measurement later in pregnancy has been proposed. Objectives: To evaluate whether CL measurement at 26±1 weeks in asymptomatic high-risk patients improves the prediction of sPTB recurrence. Methods: A retrospective cohort of high-risk women because of previous sPTB was analyzed. Patients with a CL ≥25 mm at 20±1 weeks and subsequent CL measurement at 26±1 weeks were included. The exclusion criteria were incomplete follow-up, any treatment before CL assessments, and medically indicated preterm birth. The association and predictive performance of CL at 26±1 weeks for sPTB was studied. Results: Of 131 patients with a CL measurement at 26±1 weeks, 19 and 4.6% presented sPTB before 37 and 34 weeks, respectively. The rate of sPTB before 37 weeks was higher in women with a CL <25 mm (37.5 vs. 16.5%, RR 2.3 [1.07–4.8], p = 0.045), although the detection rate of CL at 26±1 weeks to predict sPTB before 37 weeks was 24% (95% CI 10–46%). The performance did not improve regardless of the selected cutoff. Conclusions: In asymptomatic high-risk patients, CL <25 mm at 26±1 weeks is associated with higher risk of sPTB. However, the prediction of recurrence by CL was low and did not improve, regardless of the selected cutoff.

P29.09: The use of long‐term indomethacin stabilises cervical length in twin pregnancies

To determine if the use of early onset (less than 25 weeks) long-term indomethacin therapy (greater than 48 hours) (LIT) stabilises the cervical length (CL) in dichorionic-diamniotic twin gestations (DCDA-T) that are complicated by a short cervix. DCDA-T pregnancies with short CL (less than 30mm) after 18 weeks were identified. Serial CL measurements, other treatments (17 OH-P, vaginal progesterone, nifedipine) and outcomes were collected. Patients with cervical cerclage were excluded. The degree of cervical shortening from initial to last examination was compared in patients with a short CL and women with a normal CL at same gestational age (GA). Longitudinal analysis of the change in CL was modelled using mixed-model regression analysis and predicted values were compared using comparisons of the slope analysis. Out of 63 patients, 25 (40%) received LIT. The GA at initial ultrasound was similar between groups (P=0.6). There were no differences between the two groups regarding history of preterm birth and use of progesterone or nifedipine. The initial and last CLs were shorter in LIT group (24mm vs 43mm and 10mm vs 36.5mm). The average duration of indocin use was 49 days. A total of 255 (LIT=165, Normal CL=90) longitudinal CL examinations were used for mixed-model regression analysis. CL improved or did not change in LIT group (0-0.6mm/week)(CL= -0.0003GA2 + 0.7292GA - 0.0458, R2=0.046). However, in normal CL group, CL declined by 0.06-1.9mm/w (CL=0.091GA2 - 5.98GA+126.14, R2=0.21)(p<0.001). There were no reportable antenatal side effects. Early onset long-term indomethacin therapy in DCDA-T with a short cervix provides an alternative treatment modality to stabilise cervix.

P01.03: Ultrasound assessment of cervical length and volume: comparison of transabdominal and transvaginal approach

We investigate the reliability of transabdominal (TA) 3D measurements of the cervical volume (CV) by comparison with transvaginal sonography for CV measurement. All singleton pregnancies were included and women who already had a diagnosis of preterm labour, PROM, IIOC in the current pregnancy were excluded. For determination of the CV using VOCAL software. We assessed the correlation of TA and TV measurements. In addition, the discrepancies between TA and TV sonography were analysed to investigate the practical usefulness of TA sonography for the variable maternal and fetal conditions. A paired t test and Pearson correlation were used to compare the two parameters according to approach method. A total of 300 pregnant women were enrolled in this study. The mean GA was 33±3.6 years. The mean CL and CV were 34.5 ± 9.5 cm and 35.1 ± 12.9cm3 on TAS and 33.5 ± 9.7 cm and 35.1 ± 12.9cm3 on TVS, respectively. There was no significant difference between these means of CL and CV(Pearson r = 0.76 vs r=0.91, respectively). There are no significant discrepancy between TV and TA measurement of both parameter for the variable fetal and maternal condition; fetal presentation, maternal abdominal wall thickness, bladder filling state, maternal age, amniotic fluid index. Preterm birth group (N=16, 7.4%) had more shorter and smaller TV CL, CV(30.0 ± 12.1mm vs 34.0 ± 0.93mm, p 0.01 and 29.30 ± 9.3 cm3 vs 35.47 ± 13.14 cm3 p 0.03, respectively) than term birth group. CV measurement did not add any benefit compared with the CL measurement for prediction of preterm birth. But in subgroup analysis, CV measurement had additional benefit compared with the CL for prediction of preterm birth in normal cervical length group. In conclusion, the evidence for the clinical application of cervical volume screening is still insufficient. If TA CL is normal, it could be useful to try the TACV measurement. This step-by-step approach may be more convenient and useful to both patients and physicians for cervical length screening.

The Use of Long-Term Indomethacin Stabilizes Cervical Length in Twin Pregnancies [7Q

INTRODUCTION: To determine if the use of early onset (less than 25 weeks) long-term indomethacin therapy (greater than 48 hours) (LIT) stabilizes the cervical length (CL) in dichorionic-diamniotic twin gestations (DCDA-T) that are complicated by a short cervix. METHODS: DCDA-T pregnancies with short CL (less than 30 mm) after 18 weeks were identified. Serial CL measurements, other treatments (17 OH-P, vaginal progesterone) and outcomes were collected. Patients with cervical cerclage were excluded. The degree of cervical shortening from initial to last examination was compared in patients with a short CL and women with a normal CL at same gestational age (GA). Longitudinal analysis of the change in CL was modeled using mixed-model regression analysis and predicted values were compared using comparisons of the slope analysis. RESULTS: Out of 77 patients, 32 (42%) received LIT. The GA at initial ultrasound was similar between groups (P=0.6). Initial and last CLs were shorter in LIT group (21 mm vs 43 mm and 11.5 mm vs 36 mm) (P &lt; .0001 for both). A total of 434 (LIT=191, Normal CL=243) longitudinal CL examinations were used for mixed-model regression analysis. CL improved or did not change in LIT group (0-0.4 mm/week) (CL= 0.0353GA2-1.5458GA+32.399, R2=0.06). However, in normal CL group, CL was declined by 0.8-1.9 mm/w (CL=0.0529GA2-4.1356x+105.25) (P &lt; .00001). There were no reportable antenatal side effects. CONCLUSION: Early onset long-term indomethacin therapy in DCDA-T with a short cervix provides an alternative treatment modality to stabilize cervix.

Cervical length at mid-gestation in screening for preterm birth in twin pregnancy.

Short cervical length (CL) in mid-gestation is considered predictive of spontaneous preterm birth (PTB). The medical literature suggests 20 mm as the cut-off for high risk in twin pregnancies. Our objective was to assess the predictive value of CL for spontaneous PTB < 32 weeks' gestation in twin pregnancies and to calculate the cut-off point with the best sensitivity and specificity. This was a single-center retrospective cohort study of women in whom CL had been measured by transvaginal ultrasound at 18-23 weeks' gestation. Pregnancies complicated by twin-to-twin transfusion syndrome, those requiring intrauterine therapy or those with indicated PTB were excluded. The predictive value of CL for PTB < 32 weeks was assessed. The distribution of CL measurements and the optimal cut-off in patients with PTB were calculated and logistic regression analysis was performed to assess the association between pregnancy characteristics and PTB. A total of 940 twin pregnancies were included. CL showed an area under the receiver-operating characteristics curve of 0.65 (95% CI, 0.58-0.71) for the prediction of PTB < 32 weeks. The optimal cut-off value for predicting PTB was 36 mm (sensitivity, 64.1%; specificity, 62.8%; positive predictive value, 13.5%; negative predictive value, 95.1%; accuracy, 62.9%). The relative risk of PTB with CL ≤ 36 mm was 2.35 (95% CI, 1.53-3.60; P < 0.001). After adjusting for confounders in logistic regression analysis, only CL (adjusted odds ratio (aOR), 0.94 (95% CI, 0.90-0.99); P = 0.03), and not monochorionicity (aOR 4.14 (95% CI, 0.89-19.25); P = 0.07), was independently associated with PTB. More than one-third (36%) of PTB cases delivering < 32 weeks had a normal CL in mid-gestation. This proportion rose to 85% when considering the 20-mm cut-off suggested by the medical literature. This study shows that, despite the weak independent association, CL assessed in mid-gestation is a poor predictor of PTB < 32 weeks' gestation in asymptomatic twin pregnancies. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

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.

Investigating the mechanical function of the cervix during pregnancy using finite element models derived from high-resolution 3D MRI

Preterm birth is a strong contributor to perinatal mortality, and preterm infants that survive are at risk for long-term morbidities. During most of pregnancy, appropriate mechanical function of the cervix is required to maintain the developing fetus in utero. Premature cervical softening and subsequent cervical shortening are hypothesized to cause preterm birth. Presently, there is a lack of understanding of the structural and material factors that influence the mechanical function of the cervix during pregnancy. In this study we build finite element models of the pregnant uterus, cervix, and fetal membrane based on magnetic resonance imagining data in order to examine the mechanical function of the cervix under the physiologic loading conditions of pregnancy. We calculate the mechanical loading state of the cervix for two pregnant patients: 22 weeks gestational age with a normal cervical length and 28 weeks with a short cervix. We investigate the influence of (1) anatomical geometry, (2) cervical material properties, and (3) fetal membrane material properties, including its adhesion properties, on the mechanical loading state of the cervix under physiologically relevant intrauterine pressures. Our study demonstrates that membrane–uterus interaction, cervical material modeling, and membrane mechanical properties are factors that must be deliberately and carefully handled in order to construct a high quality mechanical simulation of pregnancy.

The association of beta-2 adrenoceptor genotype with short-cervix mediated preterm birth: a case-control study.

To determine whether β2 -adrenoceptor (β2 AR) genotype is associated with shortening of the cervix or with preterm birth (PTB) risk among women with a short cervix in the second trimester. A case-control ancillary study to a multicentre randomised controlled trial. Fourteen participating centres of the Maternal-Fetal Medicine Units Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Four hundred thirty-nine women, including 315 with short cervix and 124 with normal cervical length. Nulliparous women with cervical length <30 mm upon a 16-22-week transvaginal sonogram and controls frequency-matched for race/ethnicity with cervical lengths ≥40 mm were studied. β2 AR genotype was determined at positions encoding for amino acid residues 16 and 27. Genotype distributions were compared between case and control groups. Within the short cervix group, pregnancy outcomes were compared by genotype, with a primary outcome of PTB <37 weeks. Genotype data were available at position 16 for 433 women and at position 27 for 437. Using a recessive model testing for association between short cervix and genotype, and adjusted for ethnicity, there was no statistical difference between cases and controls for Arg16 homozygosity (OR 0.7, 95% CI 0.4-1.3) or Gln27 homozygosity (OR 0.9, 95% CI 0.3-2.7). Among cases, Arg16 homozygosity was not associated with protection from PTB or spontaneous PTB. Gln27 homozygosity was not associated with PTB risk, although sample size was limited. β2 AR genotype does not seem to be associated with short cervical length or with PTB following the second-trimester identification of a short cervix. Influences on PTB associated with β2 AR genotype do not appear to involve a short cervix pathway.

Reference range of the weekly uterine cervical length at 8 to 38 weeks of gestation in the center of Iran.

Background:There is an inverse relation between the uterine cervical length during pregnancy and the frequency of preterm delivery. The purpose of this study was to construct a chart and evaluate the cervical length at 8 to 38 weeks of normal gestation in the center of Iran.Materials and Methods:Uterine cervical length was measured on 930 asymptomatic pregnant women by abdominal ultrasonographic technique. For statistical evaluation, regression analysis and calculation of percentiles were performed.Results:Our data show a significant decrease in uterine cervical length with increasing gestational age. The mean uterine cervical length exhibits minimal changes from 10 to 24 weeks for most women in this study, although the shortening is more prominent at 33 to 38 weeks’ gestation. The mean shortening of the uterine cervical length between the second and the ninth months was 14.82% (P < 0.05). Also, the cervical length means in trimesters 1, 2 and 3 were 39.30 ± 4.33, 38.28 ± 5.13 and 36.58 ± 4.58 mm, respectively. The third trimester showed a significant reduction (P < 0.05) in cervical length compared to the first and second trimesters (6.92% and 4.44%, respectively). New charts with the 5th, 10th, 50th, 90th, and 95th percentile are presented.Conclusion:Our study provides a new chart and reference values for normal uterine cervical length throughout gestation based on a large sample in the center of Iran. There was a progressive decrease in mean uterine cervical length with increasing gestational age in the population of this study. Our established charts for uterine cervical length throughout gestation might be more useful than a single cut-off value for more efficient prevention and management of preterm birth.

Predicting preterm birth in women with previous preterm birth and cervical length ≥ 25 mm

To identify risk factors predicting subsequent spontaneous preterm birth or preterm prelabor rupture of membranes (PPROM) in a cohort of women with a history of spontaneous preterm birth and a cervical length of ≥ 25 mm at 20-24 weeks' gestation. We identified all pregnant women who attended our preterm labor clinic between January 2010 and December 2012 because of previous spontaneous preterm birth or PPROM before 34 weeks. Women with a normal cervical length (defined as ≥ 25 mm) between 20 and 24 weeks' gestation were identified and included in the analysis. Maternal characteristics, obstetric history, shortest cervical length and gestational age at shortest cervical length of women who delivered preterm (before 37 weeks) were compared with those who delivered at or after 37 weeks in the index pregnancy. Multiple regression analysis was planned to examine the relationship between significant clinical and cervical-length variables to identify significant clinical predictors of spontaneous preterm birth among high-risk patients with a normal cervix between 20 and 24 weeks' gestation. Of 134 women with a normal cervix at 20-24 weeks, 28 (20.9%) delivered spontaneously or had PPROM before 37 weeks; of these 12 (9.0%) delivered before 34 weeks. None of the selected explanatory variables was predictive of recurrent preterm birth in this cohort. No correlation between absolute cervical length and gestational age at delivery was found (R = 0.01). In high-risk women with a cervical length of ≥ 25 mm at 20-24 weeks' gestation, demographic characteristics and absolute cervical length are not useful in predicting subsequent spontaneous preterm birth.

Kinematic analysis of the cervical cord and cervical canal by dynamic neck motion.

Study DesignNormal cervical sagittal length patterns were measured by magnetic resonance imaging (MRI).PurposeThe aim of this study was to evaluate the relationship of sagittal length patterns between the cervical cord and the cervical canal in flexion-extension kinematics.Overview of LiteratureCervical dynamic factors sometimes cause a cervical spondylotic myelopathy in elderly subjects and an overstretching myelopathy in juvenile subjects. Previous studies showed the length changing of the cervical cord in flexion and extension. However, there is no detailed literature about the relationship between cervical vertebral motion and cord distortion yet.MethodsSixty-two normal subjects (28 male and 34 female, 42.1±8.5 years old) without neck motion disturbances and abnormalities on cervical X-ray and MRI were enrolled in this study.ResultsThe cervical cord length was significantly longer in flexion and significantly shorter in extension in all cervical cord sagittal lines. The cervical canal length pattern was also the same as the cervical cord. The elongation of the cervical cord and canal was the largest at the site of the posterior cervical canal and the shortest at the anterior canal site. The positions of the cerebellar tonsils were verified at each neck position.ConclusionsThe posterior elements of the cervical canal were most affected by neck motion. Movement directions of the upper cervical cord were verified among the various neck positions.

Prophylactic progesterone and preterm labor in low-risk twin pregnancies

Objectives The aim of the study was to study the role of vaginal progesterone versus placebo in preventing preterm birth in twin pregnancies with a normal cervical length in the second trimester and its neonatal outcome. Study design The study was designed as a randomized controlled trial. Patients and methods A total of 100 women with twin pregnancies were enrolled and randomized to receive daily either 200 mg vaginal progesterone or placebo for 10 weeks from 24–34 weeks of gestation. They all underwent detailed first and second trimester anomaly scans and cervical length assessment. Patients with anomalies, monochorionic twins, medical disorders, or a cervical length less than 25 mm were excluded. Results Patients’ demographic details, age, weight, parity, and previous risk factors were not statistically different between the two groups. The mean cervical length was 34 mm in the progesterone group and 36 mm in the placebo group. Mean gestational age at delivery was 35.7 weeks with a mean birth weight of 2160 g in the progesterone group, which was not significantly different from the placebo group with a mean gestational age of 35.6 weeks and a mean birth weight of 2210 g. Fetal complications or neonatal ICU admissions were not different in the two groups. Conclusion Although vaginal progesterone reduces preterm birth and neonatal complications in singletons with a short cervix, its role in twin pregnancies with a normal cervical length is unclear and needs a larger study to prove its merit.