Cerclage for Short Cervix on Ultrasonography

Clinical management of the short cervix

Cervical cerclage is associated with prolongation of gestation in singleton pregnancies with prior spontaneous preterm delivery and a short cervix on vaginal ultrasonography in the mid-trimester. Ultrasound screening of cervical length is not indicated in low-risk singleton pregnancies and in women with multiple gestations. 17α-Hydroxyprogesterone does not prevent preterm delivery in twin gestations with a short cervix. Cervical cerclage may cause detrimental effects in twin gestations. Vaginal pessary for the prevention of preterm birth in women with a short cervix is currently under active investigation.

Prevention of preterm delivery in twin gestations (PREDICT): a multicenter, randomized, placebo-controlled trial on the effect of vaginal micronized progesterone

OBJECTIVE

Studies on high-risk singleton gestations have shown a preventive effect of progesterone treatment on preterm delivery. This study was conducted to investigate the preventive effect of vaginal micronized progesterone in a large population of twin gestations.

METHODS

This was a double-blind, placebo-controlled randomized trial performed in 17 centers in Denmark and Austria. Women with twin gestations were randomized to daily treatment with progesterone pessaries or apparently identical placebo pessaries, starting from 20-24 weeks until 34 weeks' gestation. Primary outcome was incidence of delivery before 34 weeks' gestation. Secondary outcomes were maternal and neonatal complications and long-term infant follow-up, by Ages and Stages Questionnaire (ASQ), 6 months and 18 months after the expected date of delivery. We also updated a published meta-analysis to include our data and those of another recently published twin trial.

RESULTS

A total of 677 women were randomized to the two treatments. Two women in the placebo group were lost to follow-up. Baseline characteristics for the groups were similar. Incidence of delivery before 34 weeks was 15.3% in the progesterone group vs 18.5% in the placebo group (odds ratio, 0.8 (95% CI, 0.5-1.2)). Risks of maternal and neonatal complications were comparable for the two groups. Mean ASQ scores at 6 months and 18 months were not significantly different between the two groups (215 for infants in the progesterone group and 218 for infants in the placebo group at 6 months (P = 0.45) and 193 and 194, respectively, at 18 months (P = 0.89)). The meta-analysis gave a pooled odds ratio of 1.06 (95% CI, 0.86-1.31).

CONCLUSION

Progesterone treatment did not prevent preterm delivery in twin gestations. There were no harmful effects to fetuses and infants of maternal progesterone treatment.

The rate of cervical change and the phenotype of spontaneous preterm birth

OBJECTIVE

Preterm birth is classified by the presence of uterine contractions and/or amniorrhexis at clinical presentation. This classification does not include prior cervical change. We hypothesized that the rate of cervical shortening before preterm birth would not differ according to clinical presentation.

STUDY DESIGN

We analyzed data from a completed study of paired cervical ultrasound measurements to test our hypothesis. Cervical ultrasound measurements obtained 4 weeks apart in the second trimester were related to gestational age and clinical presentation at birth.

RESULTS

Of 2521 eligible women, 128 were delivered after preterm labor and 106 after preterm membrane rupture; 89 delivered preterm for a medical or obstetrical indication; 2198 delivered at term. The rate of change was similar in women who presented with preterm labor (-0.96 mm/week) and preterm ruptured membranes (-0.82 mm/week).

CONCLUSION

Cervical shortening occurs at the same rate before spontaneous preterm birth, regardless of presentation.

Cervical length measurement for the prediction of preterm birth in multiple pregnancies: a systematic review and bivariate meta-analysis

OBJECTIVES

To review the literature on cervical length as a predictor of preterm birth in asymptomatic women with a multiple pregnancy.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Perioperative complications of history-indicated and ultrasound-indicated cervical cerclage

OBJECTIVE

To evaluate perioperative complications of history- and ultrasound-indicated cerclage.

METHODS

We performed a retrospective observational study of a cohort of patients who underwent history- (n = 198) or ultrasound-indicated (n = 89) cerclage procedures. We evaluated the rates of perioperative complications based on indication for cerclage. The χ(2) was used for categorical variables and Student t test for continuous data.

RESULTS

One patient (0.35%) had an intraoperative complication (unsuccessful regional anesthesia) and 1 patient (0.35%) had a postoperative complication (contractions and bleeding 2 weeks after cerclage placement, delivered a nonviable infant). Peripartum complications included chorioamnionitis (6.2%), preterm premature rupture of membranes (11%), preterm delivery (20%), and delivery before 32 weeks' gestational age (8%), and they were similar in the history-indicated and ultrasound-indicated groups.

CONCLUSION

History- and ultrasound-indicated cerclages are associated with a 0.6%; 95% confidence interval, -0.26 to 1.66 risk of perioperative complications. There was no difference in perioperative complications or outcome between the 2 groups.

Follow-up cervical length in asymptomatic high-risk women and the risk of spontaneous preterm birth

OBJECTIVE

To determine whether further cervical length shortening by transvaginal ultrasonography in asymptomatic high-risk women with a short cervical length adds additional predictive value for spontaneous preterm birth and perinatal morbidity.

STUDY DESIGN

Women with a history of spontaneous preterm birth, loop electrosurgical excision procedure, cone biopsy or uterine anomaly, who were pregnant with singleton gestations and were found by transvaginal ultrasonography to have a cervical length <3.0 cm at 20 to 28 weeks' gestation, and who underwent a follow-up cervical length within 3 weeks were evaluated, comparing those with further cervical length shortening (>10%) to those without further shortening. Primary outcomes were spontaneous preterm birth <35 weeks' gestation and perinatal morbidity. Secondary outcomes included spontaneous preterm birth <37 weeks, <34 weeks, <32 weeks, birth weight <2500 g, maternal and other neonatal outcomes.

RESULT

Compared with women without further cervical shortening, those with further shortening were found by univariate analyses to have higher rates of spontaneous preterm birth <35 weeks (34.8 versus 8.5%, P = 0.014), <37 weeks (56.5 versus 21.3%, P = 0.003), <34 weeks (30.4 versus 2.1%, P = 0.001), <32 weeks (21.7 versus 0%, P = 0.003), birth weight <2500 g (60.9 versus 17.0%, P<0.0001), neonatal intensive care unit admission (47.8 versus 17.0%, P = 0.006) and composite perinatal morbidity (43.5 versus 14.9%, P = 0.009). Logistic regression revealed the only independent predictors of spontaneous preterm birth <35 weeks were further cervical length shortening (adjusted odds ratio (aOR) 5.73; 95% confidence interval (CI) 1.31 to 24.43) and gestational age at short cervical length (aOR 0.95; 95% CI 0.91 to 0.99).

CONCLUSION

Further cervical length shortening in asymptomatic high-risk women with a short cervical length is an important independent predictor of spontaneous preterm birth <35 weeks and perinatal morbidity.

Prediction of spontaneous preterm delivery from maternal factors, obstetric history and placental perfusion and function at 11-13 weeks

OBJECTIVE

To develop a model for prediction of spontaneous delivery before 34 weeks based on maternal factors, placental perfusion and function at 11-13 weeks' gestation.

METHODS

Two groups of studies: first, screening study of maternal characteristics, serum pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotrophin (β-hCG) and uterine artery pulsatility index (PI). Second, case-control studies of maternal serum or plasma concentration of placental growth factor (PlGF), placental protein 13 (PP13), a disintegrin and metalloprotease 12 (ADAM12), inhibin-A and activin-A. Regression analysis was used to develop a model for the prediction of spontaneous early delivery.

RESULTS

Spontaneous early delivery occurred in 365 (1.1%) of the 34 025 pregnancies. A model based on maternal factors could detect 38.2% of the preterm deliveries in women with previous pregnancies at or beyond 16 weeks and 18.4% in those without, at a false positive rate (FPR) of 10%. In the preterm delivery group, compared with unaffected pregnancies there were no significant differences in the markers of placental perfusion or function, except for PAPP-A which was reduced.

CONCLUSIONS

Patient-specific risk of preterm delivery is provided by maternal factors and obstetric history. Placental perfusion and function at 11-13 weeks are not altered in pregnancies resulting in spontaneous early delivery.

Prediction of spontaneous preterm delivery from endocervical length at 11 to 13 weeks

OBJECTIVE

To define the potential value of endocervical length at 11 to 13 weeks' gestation in the prediction of spontaneous early delivery.

METHOD

The lengths of the endocervix and cervico-isthmic complex were measured by transvaginal ultrasound at 11 to 13 weeks in singleton pregnancies, including 1492 that subsequently delivered after 34 weeks and 16 (1.1%) who had spontaneous delivery before 34 weeks. In 1320 of the cases, the measurements were repeated at 20 to 24 weeks.

RESULTS

There were significant associations in the length of the endocervix and cervico-isthmic complex between 11 to 13 and 20 to 24 weeks (r = 0.548, p < 0.0001 and r = 0.194, p < 0.0001), and the respective median lengths were 32.4 and 32.2 mm for the endocervix and 45.3 and 40.4 mm for the cervico-isthmic complex. At 11 to 13 weeks in the early delivery group, compared to unaffected pregnancies, the median endocervical length was shorter (27.5 vs 32.5 mm, p < 0.0001), but there was no significant difference in the length of the cervico-isthmic complex (41.4 vs 45.4 mm, p = 0.054).

CONCLUSION

In the measurement of cervical length, the endocervix should be distinguished from the isthmus. The endocervical length at 11 to 13 weeks is shorter in pregnancies resulting in spontaneous delivery before 34 weeks than in those delivering after 34 weeks.

Turning the pyramid of prenatal care

The current approach to prenatal care, which involves visits at 16, 24, 28, 30, 32, 34 and 36 weeks and then weekly until delivery, was established 80 years ago. The high concentration of visits in the third trimester implies, firstly, that most complications occur at this late stage of pregnancy and, secondly, that most adverse outcomes are unpredictable during the first or even second trimester. This review presents evidence that many pregnancy complications can now be predicted at an integrated first hospital visit at 11-13 weeks by combining data from maternal characteristics and history with findings of biophysical and biochemical tests. It is therefore proposed that the traditional pyramid of care should be inverted with the main emphasis placed in the first rather than third trimester of pregnancy.

C-reactive protein levels at pre-/post-indicated cervical cerclage predict very preterm birth

AIMS

To investigate the relation between serum levels of C-reactive protein (CRP) at pre-/post-cerclage points and preterm birth at <33 weeks of gestation in women with indicated cervical cerclage (CC).

METHODS

Fifty-eight women with CC indicated for a short or soft cervix, but no visible or protruding fetal membranes into the vagina, between 17 and 26 weeks of gestation, were reviewed. Serum CRP levels were examined three times: just before cerclage, and on day 1 and day 2 post-cerclage.

RESULTS

Serum CRP levels on day 1 and day 2, but not just before cerclage, predicted the occurrence of very preterm birth. In women with cervical dilatation of <3.0 cm, serum CRP levels on post-cerclage day 1 were associated with the increase of very preterm birth [CRP ≥1.5 mg/dL vs. <1.5 mg/dL: 4/5 (80%) vs. 8/31 (26%), P=0.033]. In women with cervical dilatation of <3.0 cm, serum CRP ≥3.0 mg/dL on post-cerclage day 2 was also associated with the increase of very preterm birth.

CONCLUSION

In women with indicated CC between 17 and 26 weeks of gestation, increased levels of serum CRP on post-cerclage day 1 or 2 might be ominous signs for very preterm birth.

Endocervical hyaluronan and ultrasound-indicated cerclage

OBJECTIVE

To investigate whether, at the time of ultrasound-indicated cerclage, the endocervical concentration of hyaluronan (HA), 27-kDa heat shock protein (HSP-27) and/or interleukin-8 (IL-8) would predict pregnancy outcome.

METHODS

Endocervical samples, obtained from 40 women undergoing ultrasound-indicated cerclage at 15 + 3 to 25 + 0 weeks' gestation, were assayed by enzyme-linked immunosorbent assay for HA, HSP-27 and IL-8. All subjects had a cervical length of < 1.5 cm or dramatic cervical length change on serial endovaginal ultrasound, no uterine contractions or tenderness, no fever and intact membranes and underwent a modified Shirodkar cerclage.

RESULTS

The median HA level was 10.0 ng/mL in the 12 women who delivered at < 37 weeks' gestation as opposed to 39.7 ng/mL in the 28 women delivering at 37-41 weeks (P = 0.017). Median HSP-27 and IL-8 concentrations were not significantly different in these groups.

CONCLUSION

A higher endocervical HA level at the time of ultrasound-indicated cerclage is associated with a longer interval before birth.

The effectiveness of medical interventions aimed at preventing preterm birth: a literature review

BACKGROUND

Preterm birth is a significant global health problem with serious short and long term consequences. This paper reviews the research literature to answer the question how effective are the medical interventions that aim to reduce the rates of preterm birth?

METHODS

A systematic search was carried out in CINAHL, Cochrane, Medline and Embase in relation to following medical treatments aimed at preventing preterm births: anti-infective medications, tocolytics, progesterone and cervical cerclage. The research underpinning each type of intervention is critically analysed in order to establish the validity of knowledge claims that are made for each type of intervention.

FINDINGS

In relation to reducing the rates of preterm births, anti-infectives are only effective in the presence of known infection. Screening for infections during pregnancy is ineffective. Tocolytic agents are not effective in decreasing the preterm birth rates. Progesterone seems to be effective in a select group of pregnant women at higher risk of preterm birth. Cervical cerclage plays a small and an occasional role in preventing some preterm births.

CONCLUSIONS

This literature review demonstrates that medical interventions aimed at preventing, not just delaying, preterm birth, are not effective at a population level. Providing holistic, antenatal midwifery care for women living in socio-economic disadvantage and/or with an increased risk of preterm birth seems to be a promising strategy to address the negative effects of the social determinants of disease and thus to reduce the rate of preterm births at an individual and a population level.

Preventing preterm birth and neonatal mortality: exploring the epidemiology, causes, and interventions

Globally, each year, an estimated 13 million infants are born before 37 completed weeks of gestation. Complications from these preterm births are the leading cause of neonatal mortality. Preterm birth is directly responsible for an estimated one million neonatal deaths annually and is also an important contributor to child and adult morbidities. Low- and middle-income countries are disproportionately affected by preterm birth and carry a greater burden of disease attributed to preterm birth. Causes of preterm birth are multifactorial, vary by gestational age, and likely vary by geographic and ethnic contexts. Although many interventions have been evaluated, few have moderate-to high-quality evidence for decreasing preterm birth: smoking cessation and progesterone treatment in women with a high risk of preterm birth in low- and middle-income countries and cervical cerclage for those in high-income countries. Antepartum and postnatal interventions (eg, antepartum maternal steroid administration, or kangaroo mother care) to improve preterm neonatal survival after birth have been demonstrated to be effective but have not been widely implemented. Further research efforts are urgently needed to better understand context-specific pathways leading to preterm birth; to develop appropriate, efficacious prevention strategies and interventions to improve survival of neonates born prematurely; and to scale-up known efficacious interventions to improve the health of the preterm neonate.

Preterm and term labour in multiple pregnancies

The association between multiple pregnancy and preterm labour is well-established, with >50% of multiple births delivering before 37 weeks. However, there remains limited understanding of the factors predisposing to early delivery of twins. Physiological stimuli to the onset of parturition, including stretch, placental corticotrophin-releasing hormone and lung maturity factors, may be stronger in multiple pregnancies due to the increased fetal and placental mass. Pathological processes including infection and cervical insufficiency also have a role. Treatments that prevent preterm birth in singleton pregnancies, such as progesterone and cervical cerclage appear to be ineffective in multiple pregnancies. This article reviews aspects of preterm birth in twins and higher order multiples including epidemiology, prediction and prevention of preterm labour and potential mechanisms controlling onset of parturition. Evidence relating to the management of labour in preterm and term multiples is also discussed.

Association between second-trimester cervical length and spontaneous preterm birth in twin pregnancies

OBJECTIVE

The purpose of this study was to define normal second-trimester cervical length (CL) measurements and to estimate the association between second-trimester CL and spontaneous preterm birth (SPTB) in twin pregnancies.

METHODS

A retrospective cohort of 309 asymptomatic patients with twin pregnancies who had routine outpatient CL assessment in the second trimester was studied. We looked at the gestational age periods of 16 to 17 6/7, 18 to 19 6/7, 20 to 21 6/7, and 22 to 23 6/7 weeks. We estimated the association between the CL measurement during each period and SPTB. A short CL was defined both as a CL at or below the 10th percentile for gestational age and 25 mm or less. We also performed regression analyses controlling for a number of clinically important factors: maternal age, chorionicity, in vitro fertilization, multifetal reduction, prior term births, prior preterm births, prepregnancy body mass index, and cerclage.

RESULTS

The CL measurement at 16 to 17 6/7 weeks was not associated with gestational age at delivery or SPTB. At 18 to 19 6/7 and 20 to 21 6/7 weeks, the CL measurement was not significantly associated with gestational age at delivery or SPTB before 28 and 32 weeks. There was an association with SPTB before 35 weeks. At 22 to 23 6/7 weeks, the CL measurement had a significant association with gestational age at delivery and SPTB before 28, 32, and 35 weeks (P < .05). A short CL at 22 to 23 6/7 weeks was significantly associated with SPTB before 32 and 35 weeks (P < .05).

CONCLUSIONS

In second-trimester twin pregnancies, the strongest association between CL and SPTB is at 22 to 23 6/7 weeks.

The risk of impending preterm delivery in asymptomatic patients with a nonmeasurable cervical length in the second trimester

OBJECTIVE

The purpose of this study was to determine the pregnancy outcome of asymptomatic patients in the second trimester with a nonmeasurable cervical length (0 mm).

STUDY DESIGN

This retrospective cohort study included 78 patients with singleton pregnancies and a sonographic nonmeasurable cervix that was detected at 14-28 weeks of gestation. Patients with cervical cerclage were excluded.

RESULTS

We found that (1) 75.3% of the patients delivered before 32 weeks of gestation; (2) the median diagnosis-to-delivery interval was 20.5 days, and the delivery rate within 7 and 14 days was 28.2% and 35.6%, respectively; and (3) patients with a nonmeasurable cervix that was diagnosed at <24 weeks of gestation had a shorter median diagnosis-to-delivery interval than patients who were diagnosed at 24-28 weeks of gestation (17.5 vs 41 days; P = .009).

CONCLUSION

Asymptomatic women with a nonmeasurable cervix in the second trimester have a median diagnosis-to-delivery interval of approximately 3 weeks. Almost 65% of these patients will not deliver within 2 weeks, yet 75% of them will deliver before 32 weeks of gestation. The earlier a nonmeasurable cervix is identified, the shorter the diagnosis-to-delivery interval.

Does midtrimester cervical length ≥25 mm predict preterm birth in high-risk women?

OBJECTIVE

We sought to assess pregnancy outcome along a continuum of cervical lengths (CLs) ≥25 mm.

STUDY DESIGN

We conducted planned secondary analysis of a randomized cerclage trial of women with prior spontaneous preterm birth 17(0)-34(6/7) weeks. Outcomes of women who maintained CLs ≥25 mm were analyzed. Women with CLs <25 mm randomized to no cerclage comprised an internal comparison group.

RESULTS

Of 1014 screened, 153 had CL <25 mm, and 672 had CL ≥25 mm. Birth <35 weeks occurred in 16% of the ≥25 mm cohort. The relationship between CLs ≥25 mm and birth gestational age was null (P = .15). In the <25 mm group, progressively shorter CLs predicted birth <35 weeks (P < .001); this relationship was null in the ≥25 mm group (P = .17).

CONCLUSION

The continuum of CLs ≥25 mm measured between 16(0/7)-22(6/7) weeks does not predict gestational length in women with prior spontaneous preterm birth.

Gestational age at previous preterm birth does not affect cerclage efficacy

OBJECTIVE

The purpose of this study was to evaluate the effect of earliest previous spontaneous preterm birth (SPTB) gestational age on cervical length, pregnancy duration, and ultrasound-indicated cerclage efficacy in a subsequent gestation.

STUDY DESIGN

Planned secondary analysis of the National Institute of Child Health and Human Development-trial of cerclage for cervical length of <25 mm. Women with at least 1 previous SPTB between 17-33 weeks 6 days of gestation underwent serial vaginal ultrasound screening between 16 and 23 weeks 6 days of gestation; cervical length at qualifying randomization evaluation was used.

RESULTS

We observed a significant correlation (P = .0008) between previous SPTB gestational age and qualifying cervical length. In a linear regression model that was controlled for cervical length and cerclage, neither previous SPTB gestational age nor the interaction between cerclage and previous birth gestational age was significant predictor of subsequent birth gestational age.

CONCLUSION

Although there is an association between previous SPTB gestational age and cervical length in women with a mid-trimester cervical length of <25 mm, there does not appear to be a disproportionate benefit of cerclage in women with earlier previous SPTB.

Twins: prevalence, problems, and preterm births

The rate of twin pregnancies in the United States has stabilized at 32 per 1000 births in 2006. Aside from determining chorionicity, first-trimester screening and second-trimester ultrasound scanning should ascertain whether there are structural or chromosomal abnormalities. Compared with singleton births, genetic amniocentesis-related loss at <24 weeks of gestation for twin births is higher (0.9% vs 2.9%, respectively). Selective termination for an anomalous fetus is an option, although the pregnancy loss rate is 7% at experienced centers. For singleton and twin births for African American and white women, approximately 50% of preterm births are indicated; approximately one-third of these births are spontaneous, and 10% of the births occur after preterm premature rupture of membranes. From 1989-2000, the rate of preterm twin births increased, for African American and white women alike, although the perinatal mortality rate has actually decreased. As with singleton births, tocolytics should be used judiciously and only for a limited time (<48 hours) in twin births. Administration of antenatal corticosteroids is an evidence-based recommendation.

Care for women with prior preterm birth

Women who have delivered an infant between 16 and 36 weeks' gestation have an increased risk of preterm birth in subsequent pregnancies. The risk increases with more than 1 preterm birth and is inversely proportional to the gestational age of the previous preterm birth. African American women have rates of recurrent preterm birth that are nearly twice that of women of other backgrounds. An approximate risk of recurrent preterm birth can be estimated by a comprehensive reproductive history, with emphasis on maternal race, the number and gestational age of prior births, and the sequence of events preceding the index preterm birth. Interventions including smoking cessation, eradication of asymptomatic bacteriuria, progestational agents, and cervical cerclage can reduce the risk of recurrent preterm birth when employed appropriately.

Repeat digital cervical assessment in pregnancy for identifying women at risk of preterm labour

BACKGROUND

Repeat digital cervical assessment (RDCA - examination of the cervix with a finger) has been promoted as a routine intervention in the antenatal clinic as a screening test for the risk of preterm birth (that is, birth occurring before 37 weeks of gestation).

OBJECTIVES

To assess the effect of repeat digital cervical assessment during pregnancy for the risk of preterm birth and other adverse effects for mother and baby.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (September 2009) and CENTRAL (The Cochrane Library 2009, Issue 3).

SELECTION CRITERIA

All known randomized clinical trials comparing repeat digital cervical assessment with internal examination limited to clinical indication or no internal examination. We have not included studies where repeat cervical assessment is only a component of complex interventions targeted at decreasing preterm birth.

DATA COLLECTION AND ANALYSIS

We evaluated relevant studies for meeting the inclusion criteria and methodological quality without considering their results. Three review authors extracted the data. For all data analyses, we entered data based on the principle of intention to treat. We calculated odds ratios and 95% confidence intervals for dichotomous data.

MAIN RESULTS

We included two trials that enrolled a total of 7163 women. Preterm birth before 37 weeks, was reported in both trials. The odds ratio for birth before 37 weeks was 1.05 (95% confidence interval 0.85 to 1.31; two trials, 6070 women). One trial (involving 5836 women) found no significant difference between the two treatment arms for the following outcomes: preterm birth before 34 weeks; preterm, prelabour rupture of membranes; hospital admission before 37 weeks; caesarean section; use of tocolytic drugs; low birthweight; very low birthweight, stillbirth, neonatal death, neonatal intensive care admissions; use of health services. The other prespecified outcomes were not evaluated in the included studies. We did not conduct the planned subgroup analyses due to insufficient data.

AUTHORS' CONCLUSIONS

We found no evidence to support the use of RDCA in pregnancy to reduce the prevalence of preterm birth. We have found insufficient evidence to assess adverse effects of the intervention.

Cervical tissue engineering using silk scaffolds and human cervical cells

Spontaneous preterm birth is a frequent complication of pregnancy and a common cause of morbidity in childhood. Obstetricians suspect abnormalities of the cervix are implicated in a significant number of preterm births. The cervix is composed of fibrous connective tissue and undergoes significant remodeling in preparation for birth. We hypothesized that a tissue engineering strategy could be used to develop three-dimensional cervical-like tissue constructs that would be suitable for investigating cervical remodeling. Cervical cells were isolated from two premenopausal women undergoing hysterectomy for a benign gynecological condition, and the cells were seeded on porous silk scaffolds in the presence or absence of dynamic culture and with 10% or 20% serum. Morphological, biochemical, and mechanical properties were measured during the 8-week culture period. Cervical cells proliferated in three-dimensions and synthesized an extracellular matrix with biochemical constituents and morphology similar to native tissue. Compared to static culture, dynamic culture was associated with significantly increased collagen deposition (p < 0.05), sulfated glycosaminoglycan synthesis (p < 0.05), and mechanical stiffness (p < 0.05). Serum concentration did not affect measured variables. Relevant human tissue-engineered cervical-like constructs constitute a novel model system for a range of fundamental and applied studies related to cervical remodeling.

Insights into the multifactorial nature of preterm birth: proteomic profiling of the maternal serum glycoproteome and maternal serum peptidome among women in preterm labor

OBJECTIVE

The purpose of this study was to identify peptide classifiers that predict spontaneous preterm birth (SPTB) among women in preterm labor (PTL) and to demonstrate specific protein pathways that are activated in PTL.

STUDY DESIGN

Serum from 110 women with PTL between 20 weeks and 33 weeks 6 days of gestation was subjected to glycoprotein purification, matrix-assisted laser desorption ionization time-of-flight mass spectrometry peptide profiling, 2-dimensional liquid chromatography tandem mass spectrometry, and pathway analysis. Women were divided into 2 groups: delivery at <34 weeks' gestation (SPTB group) and delivery at > or =34 weeks' gestation (PTL group).

RESULTS

Twenty-three peptide masses were identified that discriminated PTL from SPTB in 97% of cases. Fifty-two proteins were present differentially between PTL and SPTB; 48 of 52 proteins were classified into 1 of 4 functional pathways that were involved with PTL: (1) complement/coagulation cascade, (2) inflammation/immune response, (3) fetal-placental development, and (4) extracellular matrix proteins.

CONCLUSION

Among women in PTL, proteomic analysis of serum peptides and glycoproteins classifies women who will deliver preterm and identifies specific protein pathways at work among individuals with "idiopathic" PTL.

Patients with an asymptomatic short cervix (<or=15 mm) have a high rate of subclinical intraamniotic inflammation: implications for patient counseling

OBJECTIVE

The objective of the study was to determine the frequency and clinical significance of intraamniotic inflammation in asymptomatic women with a sonographic short cervix (SCX) in the midtrimester.

STUDY DESIGN

This cohort study included 47 asymptomatic women (14-24 weeks) with an SCX (<or=15 mm) who underwent amniocentesis. Women with multiple gestation, cerclage, or cervical dilatation greater than 2 cm were excluded. Intraamniotic inflammation was defined as an elevated amniotic fluid (AF) matrix metalloproteinase-8 concentration (>23 ng/mL).

RESULTS

(1) intraamniotic infection was found in 4.3% of patients; (2) among patients with a negative AF culture, the prevalence of intraamniotic inflammation was 22.2%; and (3) patients with a negative AF culture, but with intraamniotic inflammation, had a higher rate of delivery within 7 days (40% vs 5.7%; P=.016) and a shorter median diagnosis-to-delivery interval than those without intraamniotic inflammation (18 vs 42 days; P=.01).

CONCLUSION

Twenty-two percent of patients with a midtrimester SCX have intraamniotic inflammation. The risk of preterm delivery within 7 days for these patients is 40%.

Study of progesterone for the prevention of preterm birth in twins (STOPPIT): Findings from a trial-based cost-effectiveness analysis

Objectives: Preterm birth contributes to a range of healthcare problems amongst infants surmounting to sizeable healthcare costs. Twin pregnancies are at particular risk of preterm birth. The objective of this study was to assess the cost-effectiveness of vaginal progesterone gel for the prevention of preterm birth in twin pregnancies.

Methods: An economic evaluation was conducted alongside a randomized placebo controlled trial (the STOPPIT trial) of vaginal progesterone gel for the prevention of preterm birth in twin pregnancies. Five hundred women were recruited from nine maternity hospitals in the United Kingdom. The outcomes of the economic evaluation were presented in terms of net benefit statistics, cost-effectiveness acceptability curves, generated using the nonparametric bootstrap method, and the expected value of perfect information.

Results: Mean health service costs between the period of randomization and discharge for mother and infant were £28,031 in the progesterone group and £25,972 in the placebo group, generating a mean nonsignificant cost difference of £2,059 (bootstrap mean cost difference £2,334; 95 percent confidence interval: −£5,023, £9,142; p = .33). The probability of progesterone being cost-effective was 20 percent at a willingness to pay threshold of £30,000 per preterm birth prevented. There is little economic justification for conducting further research into the use of vaginal progesterone gel in twin pregnancies for the prevention of preterm birth.

Conclusions: Further studies of preventive interventions for preterm birth more generally are required given the scale of the clinical and economic burden of this condition. These studies should be sufficiently powered for economic endpoints and extend beyond hospital discharge.

Management strategies for the prevention of preterm birth: Part II - Update on cervical cerclage

PURPOSE OF REVIEW

Cerclage was devised more than 50 years ago based on the hypothesis that for some women, weakness or malfunction of the cervix has a causative role in the pathway to preterm birth (PTB). There have been many theories around the concept of cervical insufficiency but not much in the way of convincing evidence. The purpose of this review was to follow the recent developments in risk identification and prognostication of PTB in connection with appropriately targeted prophylactic interventions.

RECENT FINDINGS

Sonographic cervical length measurement has emerged as an effective prognosticator for PTB in all populations studied so far, independently of obstetric history, consequently deriving a wider applicability than other predictors of PTB. However, the mechanisms leading to cervical shortening are poorly understood, and it cannot be assumed that all cases with a short cervix would benefit from cerclage. Specific conditions may actually reduce the efficacy and advisability of cerclage. For this reason, attempts have been made recently to further characterize the short cervix, leading to the conclusion that only women with a short cervix in the absence of infection/inflammation may be candidates for cerclage. Furthermore, two recent randomized trials of cerclage in women with short cervix on a second trimester ultrasound suggested a benefit with cerclage in PTB rate reduction only in those cases with a cervical length of less than 15 mm.

SUMMARY

The existent literature has treated PTB prevention focusing exclusively on either progesterone use or cerclage, leaving the practitioners without any guidance on when to proceed with medical or surgical prophylaxis. Understanding that high-risk populations are not homogeneous and no single-approach modality is likely to be generally applicable, we have combined the available evidence on both progesterone and cerclage to provide guidance on how to identify subgroups of women at significantly increased risk for PTB and how to preferentially consider progesterone versus cerclage.

Effectiveness of cerclage according to severity of cervical length shortening: a meta-analysis

OBJECTIVES

To estimate the effectiveness of cerclage according to degree of cervical length (CL) shortening.

METHODS

A meta-analysis was carried out of trials of women with singleton gestations and second-trimester transvaginal sonographic CL < 25 mm randomized to cerclage or no cerclage. The degree of CL shortening was correlated to the efficacy of cerclage in preventing preterm birth.

RESULTS

There was a significant reduction in preterm birth < 35 weeks in the cerclage compared with no cerclage groups in 208 singleton gestations with both a previous preterm birth and CL < 25 mm (relative risk, 0.61; 95% CI, 0.40-0.92). In these women, preterm birth < 37 weeks was significantly reduced with cerclage for CL < or = 5.9 mm, < or = 15.9 mm, 16-24.9 mm and < 25 mm. None of the analyses for 344 women without a previous preterm birth was significant.

CONCLUSIONS

Cerclage, when performed in women with a singleton gestation, previous preterm birth and cervical length < 25 mm, seems to have a similar effect regardless of the degree of cervical shortening, including CL 16-24 mm, as well as CL < or = 5.9 mm.

17-alpha-hydroxyprogesterone caproate for the prevention of preterm birth in women with prior preterm birth and a short cervical length

OBJECTIVE

We sought to evaluate 17-alpha-hydroxyprogesterone caproate (17P) for prevention of preterm birth (PTB) in women with prior spontaneous PTB (SPTB) and cervical length (CL) <25 mm.

STUDY DESIGN

We conducted planned secondary analysis of the Eunice Kennedy Shriver National Institute of Child Health and Human Development-sponsored randomized trial evaluating cerclage for women with singleton gestations, prior SPTB (17-33 6/7 weeks), and CL <25 mm between 16-22 6/7 weeks. Women were stratified at randomization to intent to use or not use 17P. The effect of 17P was analyzed separately for cerclage and no-cerclage groups. Primary outcome was PTB <35 weeks.

RESULTS

In 300 women, 17P had no effect on PTB <35 weeks in either cerclage (P = .64) or no-cerclage (P = .51) groups. Only PTB <24 weeks (odds ratio, 0.08) and perinatal death (odds ratio, 0.14) were significantly lower for those with 17P in the no-cerclage group.

CONCLUSION

17P had no additional benefit for prevention of PTB in women who had prior SPTB and got ultrasound-indicated cerclage for CL <25 mm. In women who did not get cerclage, 17P reduced previable birth and perinatal mortality.

Global report on preterm birth and stillbirth (3 of 7): evidence for effectiveness of interventions

INTRODUCTION

Interventions directed toward mothers before and during pregnancy and childbirth may help reduce preterm births and stillbirths. Survival of preterm newborns may also be improved with interventions given during these times or soon after birth. This comprehensive review assesses existing interventions for low- and middle-income countries (LMICs).

METHODS

Approximately 2,000 intervention studies were systematically evaluated through December 31, 2008. They addressed preterm birth or low birth weight; stillbirth or perinatal mortality; and management of preterm newborns. Out of 82 identified interventions, 49 were relevant to LMICs and had reasonable amounts of evidence, and therefore selected for in-depth reviews. Each was classified and assessed by the quality of available evidence and its potential to treat or prevent preterm birth and stillbirth. Impacts on other maternal, fetal, newborn or child health outcomes were also considered. Assessments were based on an adaptation of the Grades of Recommendation Assessment, Development and Evaluation criteria.

RESULTS

Most interventions require additional research to improve the quality of evidence. Others had little evidence of benefit and should be discontinued. The following are supported by moderate- to high-quality evidence and strongly recommended for LMICs: Two interventions prevent preterm births--smoking cessation and progesterone. Eight interventions prevent stillbirths--balanced protein energy supplementation, screening and treatment of syphilis, intermittant presumptive treatment for malaria during pregnancy, insecticide-treated mosquito nets, birth preparedness, emergency obstetric care, cesarean section for breech presentation, and elective induction for post-term delivery. Eleven interventions improve survival of preterm newborns--prophylactic steroids in preterm labor, antibiotics for PROM, vitamin K supplementation at delivery, case management of neonatal sepsis and pneumonia, delayed cord clamping, room air (vs. 100% oxygen) for resuscitation, hospital-based kangaroo mother care, early breastfeeding, thermal care, and surfactant therapy and application of continued distending pressure to the lungs for respiratory distress syndrome

CONCLUSION

The research paradigm for discovery science and intervention development must be balanced to address prevention as well as improve morbidity and mortality in all settings. This review also reveals significant gaps in current knowledge of interventions spanning the continuum of maternal and fetal outcomes, and the critical need to generate further high-quality evidence for promising interventions.

Prematurity prevention: the role of cerclage

PURPOSE OF REVIEW

To summarize the literature on the value of cervical cerclage for the prevention of preterm birth and present the recent advances in its clinical application.

RECENT FINDINGS

The diagnosis of cervical insufficiency is difficult as there are no objective diagnostic criteria. Although widely used, the value of cervical cerclage is still a matter of controversy. The current literature suggests that cerclage placement can prevent preterm delivery in women with a history of at least three second-trimester losses or at least three preterm births and in those with a history of prematurity who have a cervical length of less than 25 mm in the second trimester. It is also possible to improve the perinatal outcome in patients with cervical dilation in the mid-trimester. It is not indicated in multiple pregnancies, however. Further research is needed in methods of excluding inflammation in women with cervical changes on ultrasound prior to cerclage insertion. Transabdominal or laparoscopic cerclage seems to be a promising alternative in women with a history of transvaginal cerclage failure.

SUMMARY

Strict recommendations on the proper use of cerclage cannot be easily made. Data from randomized trials do not support what the current practice in many cases is.

Prediction of spontaneous preterm birth in asymptomatic twin pregnancies using the change in cervical length over time

OBJECTIVE

We sought to evaluate the change in cervical length (CL) as a predictor of preterm birth in asymptomatic twin pregnancies.

STUDY DESIGN

We studied a historical cohort of 121 twin pregnancies with CL testing between 18-24 weeks who had a follow-up CL 2-6 weeks after the initial CL.

RESULTS

A total of 19 patients had their CL decrease by > or = 20% (shortened CL group) and 102 patients' CL decreased by less, or not at all (stable CL group). The shortened CL group had a significantly higher rate of spontaneous preterm birth <28 weeks, <30 weeks, <32 weeks, and <34 weeks. This remained true even when excluding patients with a short CL (< or = 25 mm) on the repeated CL.

CONCLUSION

In twin pregnancies, a CL that decreases by 20% over 2 measurements is a significant predictor of very preterm birth, even in the setting of a normal CL. Serial CL measurements should be considered in twin pregnancies, starting <24 weeks.

Recurrent second trimester pregnancy loss: evaluation and management

PURPOSE OF REVIEW

Recurrent pregnancy loss usually refers to first trimester losses. The present article describes the importance of a thorough evaluation for any patient presenting with a second trimester loss, and reviews current data regarding evidence-based evaluation and management for those families who have had recurrent episodes of second trimester losses. A management protocol is presented to guide management of a current pregnancy with a history of recurrent second trimester losses.

RECENT FINDINGS

Previous literature has focused on isolated causes of second trimester loss and management. The present review incorporates all presentations of loss into a stepwise evaluative and management paradigm.

SUMMARY

This comprehensive literature review and management protocol will provide the clinician with a thorough, systematic, and practical approach to the patient with recurrent pregnancy loss in order to maximize her chance of optimal pregnancy outcome.