Increased levels of interleukin-6 in cervical secretions and assessment of the uterine cervix by transvaginal ultrasonography predict preterm premature rupture of the membranes

Impact of cervical length on preterm birth in northern China: a prospective cohort study

Aim: To evaluate the association between cervical length (CL) and certain subtypes of preterm birth (PTB).Materials and methods: Data were derived from a prospective cohort study conducted in China to explore the risk factors of PTB between 2012 and 2014. Gestational age was based on transvaginal ultrasound examination during pregnancy. PTB was categorized into two subtypes according to its clinical symptoms. Logistic regression was used to evaluate the relation between short CL and certain subtypes of PTB, adjusted for potential confounders.Results: Of the 3688 women included in the analysis, 425 (11.5%) women had a CL less than 30 mm (short CL). The incidence of PTB was significantly higher in the short CL group than the normal CL group (10.6 versus 6.0%; adjusted risk ratio (RR) 1.91, 95% CI 1.35, 2.69). The association between short CL and overall PTB was both significant in primipara (adjusted RR 2.00, 95% CI 1.09, 3.68) and multipara (adjusted RR 1.89, 95% CI 1.24, 2.87). The association between short CL and noniatrogenic PTB related to parity (primipara adjusted RR 2.13, 95% CI 1.11, 4.10; multipara adjusted RR 1.90, 95% CI 1.21, 3.00).Conclusion: Short CL could increase the risk of overall PTB and noniatrogenic PTB. The association between CL and noniatrogenic PTB was dependent on parity.

Human cervicovaginal fluid biomarkers to predict term and preterm labor

Preterm birth (PTB; birth before 37 completed weeks of gestation) remains the major cause of neonatal morbidity and mortality. The current generation of biomarkers predictive of PTB have limited utility. In pregnancy, the human cervicovaginal fluid (CVF) proteome is a reflection of the local biochemical milieu and is influenced by the physical changes occurring in the vagina, cervix and adjacent overlying fetal membranes. Term and preterm labor (PTL) share common pathways of cervical ripening, myometrial activation and fetal membranes rupture leading to birth. We therefore hypothesize that CVF biomarkers predictive of labor may be similar in both the term and preterm labor setting. In this review, we summarize some of the existing published literature as well as our team's breadth of work utilizing the CVF for the discovery and validation of putative CVF biomarkers predictive of human labor. Our team established an efficient method for collecting serial CVF samples for optimal 2-dimensional gel electrophoresis resolution and analysis. We first embarked on CVF biomarker discovery for the prediction of spontaneous onset of term labor using 2D-electrophoresis and solution array multiple analyte profiling. 2D-electrophoretic analyses were subsequently performed on CVF samples associated with PTB. Several proteins have been successfully validated and demonstrate that these biomarkers are associated with term and PTL and may be predictive of both term and PTL. In addition, the measurement of these putative biomarkers was found to be robust to the influences of vaginal microflora and/or semen. The future development of a multiple biomarker bed-side test would help improve the prediction of PTB and the clinical management of patients.

Evaluation of vaginal fluid β-human chorionic gonadotrophin for the diagnosis of preterm premature rupture of membranes

AIM

The purpose of the present study was to evaluate vaginal fluid β-human chorionic gonadotrophin (β-hCG) for the diagnosis of preterm premature rupture of membranes (PPROM).

MATERIAL AND METHODS

An observational cross-sectional study was performed on 123 pregnant women who were in the third trimester of their gestation (28-37 weeks). The patients were divided into three groups: (i) PPROM group (41 cases); (ii) suspected PPROM group (42 cases); and (iii) intact membranes control group (40 cases). Five milliliters of sterile normal saline was inserted into the posterior fornix of the vagina and then vaginal fluid was aspirated and sent to the laboratory for β-hCG measurement. Finally, the amount of β-hCG was compared in the three groups.

RESULTS

β-hCG concentration was 7.71 ± 15.7 mIU/mL in the intact membrane control group, 468.06 ± 366.34 mIU/mL in the PPROM group and 176.43 ± 316.37 mIU/mL in the suspected PPROM group, which showed a significant difference between the three groups (P < 0.001). In order to find an optimal cut-off value for β-hCG, the receiver-operator curve was used and a cut-off value of 79.5 mIU/mL with a sensitivity of 95% and specificity of 84% was determined to be optimal.

CONCLUSION

β-hCG was higher in the cases of PPROM and patients who were suspected to have PPROM, and may be used as a suitable, fast and reliable test for detecting rupture of membranes.

Cervical leukocyte sub-populations in idiopathic preterm labour

OBJECTIVE

To investigate cervical epithelial leukocyte sub-populations in pregnant women with a history of idiopathic preterm labour.

METHODS

A prospective observational study was undertaken of 106 women with a past history of idiopathic preterm delivery following spontaneous labour. A cytobrush was used to sample the epithelium of the cervix at 12-16 weeks of gestation and again 8 weeks later. All women had investigations for cervical and vaginal infection as well as serial transvaginal ultrasonography of their cervix; the mode and gestation at delivery were recorded. Leukocyte sub-populations were examined using immunocytochemistry, and the number of leukocytes per total cell count was calculated.

MAIN OUTCOME MEASURES

Cervical epithelial leukocytes populations were (1) described in pregnancy, (2) observed over increasing gestation, (3) analysed in women who developed marked cervical shortening and (4) in those whose preterm labour recurred.

RESULTS

There was no significant change in cervical epithelial leukocyte populations during the second trimester of pregnancy. There was no association between cervical leukocytes and cervical shortening. Women with idiopathic preterm labour that recurred had fewer cervical macrophages at the beginning of the second trimester of pregnancy than those whose subsequent pregnancy progressed beyond 35 weeks of gestation.

CONCLUSIONS

Cervical epithelial macrophages may serve to prevent recurrent preterm labour, possibly by preventing ascending infection.

Early second-trimester inflammatory markers and short cervical length and the risk of recurrent preterm birth

This study aimed to analyze the associations between serum and cervicovaginal inflammatory markers and recurrent spontaneous preterm birth in a cohort study of 62 pregnant women with > or =1 prior early spontaneous birth. Serum samples and cervicovaginal swabs from the women were obtained at enrollment in early second trimester (week 12-25). Cervical length was measured by ultrasound and dicotomized in to short (< or =25 mm) and long cervices (>25 mm). The study endpoints were spontaneous preterm birth before 35 weeks and secondarily<37 weeks. Multiple inflammatory markers in serum (IL-1beta, IL-2, IL-5, IL-6, IL-8, IL-12, IL-18, TNF-alpha, TGF-beta, sTNF-R1, GM-CSF and TREM-1) and cervicovaginal secretions (IL-18, sTNF-RI and sIL-6) were individually associated with spontaneous preterm birth. Short cervical length did not explain associations between inflammatory markers and spontaneous preterm birth. Serum and cervicovaginal inflammatory markers did not correlate. In a combined prediction model using both serum and vaginal inflammatory markers, serum TNF-alpha, cervicovaginal sIL-6Ralpha and cervical length predicted 69% of all recurrent spontaneous preterm birth at a 5% false-positive rate. In conclusion, cervical length, serum TNF-alpha and cervicovaginal sIL-6Ralpha provide a clinically useful prediction of recurrent preterm birth in early second-trimester in women with a prior spontaneous preterm birth.

Amniotic fluid endothelin levels and the incidence of premature rupture of membranes

Objective. The purpose of this prospective study was to record Endothelin 1 (ET1) concentrations in the second trimester amniotic fluid and in women who develop premature rupture of membranes (PROM), preterm premature rupture of the membranes (PPROM) and in women with uneventful pregnancies. Method. Amniotic fluid was retrieved by amniocentesis from 125 women in the second trimester of pregnancy. The levels of Endothelin were measured by a sensitive and specific radioimmunoassay. Results. From the 125 women included in the study 20 developed PROM and preterm PROM (13 PPROM and 7 PROM). The ET1 concentration was significantly higher (P<0.001) in PROM and PPROM than in normal pregnancy (96.4 vs. 43 pg/ml). The sub-analysis of the two rupture of membranes groups found that the concentration of ET1 was higher in the PPROM than in PROM (118 vs. 72 pg/ml). Conclusion. The amniotic fluid concentration of ET1 is elevated by the second trimester in women who later develop preterm PROM or term PROM.

Biomarkers for the prediction of preterm delivery

This structured review discusses the current literature on selected biomarkers and their ability to predict preterm delivery (PTD). Among symptomatic women, the likelihood ratio (LR+) for the prediction of PTD was found to be greater than 10 using amniotic fluid (AF) interleukin-6 (IL-6), AF Ureaplasma urealyticum, as well as a multi-marker consisting of cervical IL-6, cervical IL-8, and cervical length (CL). The LR+ was found to be between 5 and 10 for serum C-reactive protein (CRP). An LR+ between 2.5 and 5 was recorded for serum corticotropin-releasing hormone (CRH), cervical fetal fibronectin (fFN), cervical IL-6, serum relaxin, and a multi-marker consisting of fFN and CL. CL and bacterial vaginosis (BV) both predicted PTD in women with preterm labor with an LR+ of less than 2.5. In asymptomatic women, AF U. urealyticum and a multimarker consisting of five individual markers [fFN, CL, serum alpha-fetoprotein (AFP), serum alkaline phosphatase, and serum granulocyte colony-stimulating factor (G-CSF)] predicted PTD with an LR+ greater than 10. The LR+ was between 5 and 10 for serum relaxin and CL. LRs+ recorded for serum alkaline phosphatase, salivary estriol, serum CRH, serum G-CSF, cervical IL-6, AF IL-6, cervical fFN, AFP, and Chlamydia all ranged between 2.5 and 5. Finally, an LR+ below 2.5 has been documented for serum ferritin, serum CRP, BV, and cervical ferritin.

Towards improved neonatal outcome: future strategies

The role of the obstetrician is to help predict and prevent maternal/fetal infection/inflammation related to neonatal mortality and morbidity. Predictive studies have mainly focused on the high-risk phenotype. Currently, there is a scientific drive to analyse the genetic susceptibility of preterm birth (PTB). Studies of the combination of environmental and lifestyle risk factors with the known genotype may result in a better understanding of the causation of PTB. Predictive technical markers such as fibronectin, cervical length measurement and home uterine activity remain largely unproven. Current antenatal care has not achieved primary prevention of PTB. Tocolytics and antibiotics constitute the two key elements of secondary prevention. Tocolytics have a minimal benefit but should not be used to prolong an infected preterm pregnancy. The use of antibiotics in preterm premature rupture of membranes can prolong the pregnancy with a decrease in neonatal morbidity. Anti-inflammatory cytokines, cytokine inhibitors and soluble cytokine receptors are promising treatment options that could modulate the intra-amniotic inflammatory process.