The Role of Genetics in Preterm Birth.

Preterm birth (PTB), defined as the birth of a child before 37 completed weeks gestation, affects approximately 11% of live births and is the leading cause of death in children under 5 years. PTB is a complex disease with multiple risk factors including genetic variation. Much research has aimed to establish the biological mechanisms underlying PTB often through identification of genetic markers for PTB risk. The objective of this review is to present a comprehensive and updated summary of the published data relating to the field of PTB genetics. A literature search in PubMed was conducted and English studies related to PTB genetics were included. Genetic studies have identified genes within inflammatory, immunological, tissue remodeling, endocrine, metabolic, and vascular pathways that may be involved in PTB. However, a substantial proportion of published data have been largely inconclusive and multiple studies had limited power to detect associations. On the contrary, a few large hypothesis-free approaches have identified and replicated multiple novel variants associated with PTB in different cohorts. Overall, attempts to predict PTB using single "-omics" datasets including genomic, transcriptomic, and epigenomic biomarkers have been mostly unsuccessful and have failed to translate to the clinical setting. Integration of data from multiple "-omics" datasets has yielded the most promising results.

Development and internal validation of a non-invasive clinical tool to predict sufficient omega-3 levels in early pregnancy.

BACKGROUND: Complications from preterm birth (PTB) are the leading cause of death and disability in those under five years. Whilst the role of omega-3 (n-3) supplementation in reducing PTB is well-established, growing evidence suggests supplementation use in those replete may increase the risk of early PTB. AIM: To develop a non-invasive tool to identify individuals with total n-3 serum levels above 4.3% of total fatty acids in early pregnancy. METHODS: We conducted a prospective observational study recruiting 331 participants from three clinical sites in Newcastle, Australia. Eligible participants (n = 307) had a singleton pregnancy between 8 and 20 weeks' gestation at recruitment. Data on factors associated with n-3 serum levels were collected using an electronic questionnaire; these included estimated intake of n-3 (including food type, portion size, frequency of consumption), n-3 supplementation, and sociodemographic factors. The optimal cut-point of estimated n-3 intake that predicted mothers with total serum n-3 levels likely above 4.3% was developed using multivariate logistic regression, adjusting for maternal age, body mass index, socioeconomic status, and n-3 supplementation use. Total serum n-3 levels above 4.3% was selected as previous research has demonstrated that mothers with these levels are at increased risk of early PTB if they take additional n-3 supplementation during pregnancy. Models were evaluated using various performance metrics including sensitivity, specificity, area under receiver operator characteristic (AUROC) curve, true positive rate (TPR) at 10% false positive rate (FPR), Youden Index, Closest to (0,1) Criteria, Concordance Probability, and Index of Union. Internal validation was performed using 1000-bootstraps to generate 95% confidence intervals for performance metrics generated. RESULTS: Of 307 eligible participants included for analysis, 58.6% had total n-3 serum levels above 4.3%. The optimal model had a moderate discriminative ability (AUROC 0.744, 95% CI 0.742-0.746) with 84.7% sensitivity, 54.7% specificity and 37.6% TPR at 10% FPR. CONCLUSIONS: Our non-invasive tool was a moderate predictor of pregnant women with total serum n-3 levels above 4.3%; however, its performance is not yet adequate for clinical use. TRIAL REGISTRATION: This trial was approved by the Hunter New England Human Research Ethics Committee of the Hunter New England Local Health District (Reference 2020/ETH00498 on 07/05/2020 and 2020/ETH02881 on 08/12/2020).

Combined vaginal progesterone and cervical cerclage in the prevention of preterm birth: a systematic review and meta-analysis.

OBJECTIVE: Vaginal progesterone and cervical cerclage are both effective interventions for reducing preterm birth. It is currently unclear whether combined therapy offers superior effectiveness than single therapy. This study aimed to determine the efficacy of combining cervical cerclage and vaginal progesterone in the prevention of preterm birth. DATA SOURCES: We searched Medline (Ovid), EMBASE (Ovid), PsycINFO (Ovid), CINAHL (EBSCOhost), Cochrane Library (Wiley), and Scopus (from their inception to 2020). STUDY ELIGIBILITY CRITERIA: The review accepted randomized and pseudorandomized control trials, nonrandomized experimental control trials, and cohort studies. High risk patients (shortened cervical length <25mm or previous preterm birth) who were assigned cervical cerclage, vaginal progesterone, or both for the prevention of preterm birth were included. Only singleton pregnancies were assessed. METHODS: The primary outcome was birth <37 weeks. Secondary outcomes included birth <28 weeks, <32 weeks and <34 weeks, gestational age at delivery, days between intervention and delivery, preterm premature rupture of membranes, cesarean delivery, neonatal mortality, neonatal intensive care unit admission, intubation, and birthweight. Following title and full-text screening, 11 studies were included in the final analysis. Risk of bias was assessed using the Cochrane Collaboration tool for assessing the risk of bias (ROBINS-I and RoB-2). Quality of evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) tool. RESULTS: Combined therapy was associated with lower risk of preterm birth at <37 weeks than cerclage alone (risk ratio, 0.51; 95% confidence interval, 0.37-0.79) or progesterone alone (risk ratio, 0.75; 95% confidence interval, 0.58-0.96). Compared with cerclage only, combined therapy was associated with preterm birth at <34 weeks, <32 weeks, or <28 weeks, decreased neonatal mortality, increased birthweight, increased gestational age, and a longer interval between intervention and delivery. Compared with progesterone alone, combined therapy was associated with preterm birth at <32 weeks, <28 weeks, decreased neonatal mortality, increased birthweight, and increased gestational age. There were no differences in any other secondary outcomes. CONCLUSION: Combined treatment of cervical cerclage and vaginal progesterone could potentially result in a greater reduction in preterm birth than in single therapy. Further, well-conducted and adequately powered randomized controlled trials are needed to assess these promising findings.

McDonald versus Shirodkar cerclage technique in the prevention of preterm birth: A systematic review and meta-analysis.

BACKGROUND: Cervical cerclage has been used for decades to reduce preterm birth. The Shirodkar and McDonald cerclage are the most commonly used techniques with no current consensus on the preferred technique. OBJECTIVE: To compare the efficacy of the Shirodkar and McDonald cerclage techniques in preventing preterm birth. SEARCH STRATEGY: Studies were sourced from six electronic databases and reference lists. SELECTION CRITERIA: Studies including women with a singleton pregnancy, requiring a cervical cerclage, using either the Shirodkar or McDonald technique that ran comparative analyses between the two techniques. DATA COLLECTION AND ANALYSIS: The primary outcome was preterm birth before 37 weeks, with analyses at 28, 32, 34 and 35 weeks. Secondary data were also collected on neonatal, maternal and obstetric outcomes. MAIN RESULTS: Seventeen papers were included: 16 were retrospective cohort studies and one was a randomised controlled trial. The Shirodkar technique was significantly less likely to result in preterm birth before 37 weeks than the McDonald technique (relative risk [RR] 0.91, 95% CI 0.85-0.98). This finding was supported by a statistically significant reduction in rates of preterm birth before 35, 34 and 32 weeks, PPROM, difference in cervical length, cerclage to delivery interval, and an increase in birthweight in the Shirodkar group. No difference was seen in preterm birth rates <28 weeks, neonatal mortality, chorioamnionitis, cervical laceration or caesarean section rates. The RR for preterm birth prior to 37 weeks was no longer significant when sensitivity analyses were performed removing studies with a serious risk of bias. However, similar analyses removing studies that utilised adjunctive progesterone strengthened the primary outcome (RR 0.83, 95% CI 0.74-0.93). CONCLUSION: Shirodkar cerclage reduces the rate of preterm birth prior to 35, 34 and 32 weeks' gestation when compared with McDonald cerclage; however, the overall quality of the studies in this review is low. Further, large, well-designed randomised controlled trials are required to address this important question to optimise care for women who may benefit from cervical cerclage.

20α-Hydroxysteroid Dehydrogenase Expression in the Human Myometrium at Term and Preterm Birth: Relationships to Fetal Sex and Maternal Body Mass Index.

The mechanism by which human labor is initiated in the presence of elevated circulating progesterone levels remains unknown. Recent evidence indicates that the progesterone-metabolizing enzyme, 20α-hydroxysteroid dehydrogenase (20α-HSD), encoded by the gene AKR1C1, may contribute to functional progesterone withdrawal. We found that AKR1C1 expression significantly increased with labor onset in term myometrium, but not in preterm myometrium. Among preterm laboring deliveries, clinically diagnosed chorioamnionitis was associated with significantly elevated AKR1C1 expression. AKR1C1 expression positively correlated with BMI before labor and negatively correlated with BMI during labor. Analysis by fetal sex showed that AKR1C1 expression was significantly higher in women who delivered male babies compared to women who delivered female babies at term, but not preterm. Further, in pregnancies where the fetus was female, AKR1C1 expression positively correlated with the mother's age and BMI at the time of delivery. In conclusion, the increase in myometrial AKR1C1 expression with term labor is consistent with 20α-HSD playing a role in local progesterone metabolism to promote birth. Interestingly, this role appears to be specific to term pregnancies where the fetus is male. Upregulated AKR1C1 expression in the myometrium at preterm in-labor with clinical chorioamnionitis suggests that increased 20α-HSD activity is a mechanism through which inflammation drives progesterone withdrawal in preterm labor. The link between AKR1C1 expression and maternal BMI may provide insight into why maternal obesity is often associated with dysfunctional labor. Higher myometrial AKR1C1 expression in male pregnancies may indicate fetal sex-related differences in the mechanisms that precipitate labor onset at term.

Preterm labor with and without chorioamnionitis is associated with activation of myometrial inflammatory networks: a comprehensive transcriptomic analysis.

BACKGROUND: The onset of preterm labor is associated with inflammation. Previous studies suggested that this is distinct from the inflammation observed during term labor. Our previous work on 44 genes differentially expressed in myometria in term labor demonstrated a different pattern of gene expression from that observed in preterm laboring and nonlaboring myometria. We found increased expression of inflammatory genes in preterm labor associated with chorioamnionitis, but in the absence of chorioamnionitis observed no difference in gene expression in preterm myometria regardless of laboring status, suggesting that preterm labor is associated with different myometrial genes or signals originating from outside the myometrium. Given that a small subset of genes were assessed, this study aimed to use RNA sequencing and bioinformatics to assess the myometrial transcriptome during preterm labor in the presence and absence of chorioamnionitis. OBJECTIVE: This study aimed to comprehensively determine protein-coding transcriptomic differences between preterm nonlaboring and preterm laboring myometria with and without chorioamnionitis. STUDY DESIGN: Myometria were collected at cesarean delivery from preterm patients not in labor (n=16) and preterm patients in labor with chorioamnionitis (n=8) or without chorioamnionitis (n=6). Extracted RNA from myometrial tissue was prepared and sequenced using Illumina NovaSeq. Gene expression was quantified by mapping the sequence reads to the human reference genome (hg38). Differential gene expression analysis, gene set enrichment analysis, and weighted gene coexpression network analysis were used to comprehensively interrogate transcriptomic differences and their associated biology. RESULTS: Differential gene expression analysis comparing preterm patients in labor with chorioamnionitis with preterm patients not in labor identified 931 differentially expressed genes, whereas comparing preterm patients in labor without chorioamnionitis with preterm patients not in labor identified no statistically significant gene expression changes. In contrast, gene set enrichment analysis and weighted gene coexpression network analysis demonstrated that preterm labor with and without chorioamnionitis was associated with enrichment of pathways involved in activation of the innate immune system and inflammation, and activation of G protein-coupled receptors. Key genes identified included chemotactic CYP4F3, CXCL8, DOCK2, and IRF1 in preterm labor with chorioamnionitis and CYP4F3, FCAR, CHUK, and IL13RA2 in preterm labor without chorioamnionitis. There was marked overlap in the pathways enriched in both preterm labor subtypes. CONCLUSION: Differential gene expression analysis demonstrated that myometria from preterm patients in labor without chorioamnionitis and preterm patients not in labor were transcriptionally similar, whereas the presence of chorioamnionitis was associated with marked gene changes. In contrast, comprehensive bioinformatic analysis indicated that preterm labor with or without chorioamnionitis was associated with innate immune activation. All causes of preterm labor were associated with activation of the innate immune system, but this was more marked in the presence of chorioamnionitis. These data suggest that anti-inflammatory therapy may be relevant in managing preterm labor of all etiologies.

Preterm labor is a distinct process from term labor following computational analysis of human myometrium.

BACKGROUND: The onset of the term human parturition involves myometrial gene expression changes to transform the uterus from a quiescent to a contractile phenotype. It is uncertain whether the same changes occur in the uterus during preterm labor. OBJECTIVE: This study aimed to compare the myometrial gene expression between term and preterm labor and to determine whether the presence of acute clinical chorioamnionitis or twin gestation affects these signatures. STUDY DESIGN: Myometrial specimens were collected during cesarean delivery from the following 7 different groups of patients: term not in labor (n=31), term labor (n=13), preterm not in labor (n=21), preterm labor with acute clinical chorioamnionitis (n=6), preterm labor with no acute clinical chorioamnionitis (n=9), twin preterm not in labor (n=8), and twin preterm labor with no acute clinical chorioamnionitis (n=5). RNA was extracted, reverse transcribed and quantitative polymerase chain reactions were performed on 44 candidate genes (with evidence for differential expression in human term labor) using the Fluidigm platform. Computational analysis was performed using 2-class unpaired Wilcoxon tests and principal component analysis. RESULTS: Computational analysis revealed that gene expression in the preterm myometrium, irrespective of whether in labor or not in labor, clustered tightly and is clearly different from the term labor and term not-in-labor groups. This was true for both singleton and twin pregnancies. Principal component analysis showed that 57% of the variation was explained by 3 principal components. These 44 genes interact in themes of prostaglandin activity and inflammatory signaling known to be important during term labor, but are not a full representation of the myometrium transcriptional activity. CONCLUSION: The myometrial contractions associated with preterm labor are associated with a pattern of gene expression that is distinct from term labor. Therefore, preterm labor may be initiated by a different myometrial process or processes outside the myometrium.

Colposcopic outcomes for symptomatic patients with a negative oncogenic human papillomavirus test.

This study assesses outcomes of colposcopy referrals for post-coital, intermenstrual, or other abnormal bleeding with negative oncogenic human papillomavirus and negative to low-grade cytology. Of 112 cases with median age of 34.5 years, cervical biopsy occurred in 19%, treatment of ectropion in 19%, endometrial sampling in 8%, polypectomy in 4%, and contraceptive change in 2%. No cervical or endometrial neoplasia was detected. Patients with bleeding symptoms and reassuring co-test may instead attend a general gynaecology clinic.

Effectiveness of combined vaginal progesterone and cervical cerclage in preventing preterm birth: a systematic review and meta-analysis protocol.

INTRODUCTION: Preterm birth (PTB) is the leading cause of death in children under 5 years. Preventive therapies targeted towards women with risk factors such as a prior PTB or a short cervix reduce the rate of PTB. Cervical cerclage, vaginal progesterone and a combination of the two have been used with no consensus as to whether combined treatment is more effective than any single treatment alone. The objective of this review is to determine the efficacy of combined treatment compared with cerclage alone and combined treatment compared with progesterone alone. METHODS AND ANALYSIS: Studies will be sourced from the electronic databases Medline (Ovid), EMBASE (Ovid), PsycINFO (Ovid), Scopus, CINAHL (EBSCOhost) and Cochrane Library (Wiley) and reference lists. We will not exclude any papers due to publication date. Randomised control trials (RCTs), non-RCTs and cohort studies assessing single therapy (either progesterone or cerclage) versus combined therapy in women with a singleton pregnancy will be included. Two independent reviewers will conduct study screening (at abstract and full-text level), data extraction and risk of bias assessment with disagreements resolved by an experienced researcher. Random or fixed effects models will be used depending on data heterogeneity and data will be presented as risk ratio for dichotomous data or mean difference for continuous data with a CI of 95% used for all outcomes. ETHICS AND DISSEMINATION: Not applicable due to nature of the study type. PROSPERO REGISTRATION NUMBER: CRD42020195975.

McDonald versus Shirodkar cerclage technique in women requiring a prophylactic cerclage: a systematic review and meta-analysis protocol.

BACKGROUND: Preterm birth (PTB) is the leading cause of death in children under five years. Spontaneous preterm birth (SPTB) is the major cause of preterm delivery. The key risk factors for SPTB are women who have a short cervix and women who have had previous preterm birth. Cervical cerclage has been used for several decades and has shown to decrease rates of preterm birth. The most commonly used cerclage techniques were described by Shirodkar and McDonald, with no current consensus on the preferred technique. The objective of this review is to determine and compare the effectiveness of both techniques. METHODS: Studies will be sourced from six electronic databases, as well as from experts in the field, reference lists, and grey literature. Eligible studies will include pregnant women, with a singleton or twin pregnancy, requiring a cervical cerclage, using either the Shirodkar or McDonald technique and run comparative analyses between the two techniques. Randomized control trials (RCT)s, non-randomized control trials, and cohort studies will be eligible. Two independent reviewers will conduct study screening at abstract and full-text level, data extraction and risk of bias assessment. Discrepancies will be resolved by a consensus third reviewer if required. Fixed-effects or random-effects models will be used where appropriate to synthesize results. Alternative synthesis methods will be investigated in instances where a meta-analysis is not appropriate, such as summarizing effect estimates, combining P values, vote counting based on direction of effect, or synthesis in narrative form. DISCUSSION: This review will synthesize the evidence on both the Shirodkar and McDonald cerclage method, and will help clinicians and health services to determine and deliver best practice antenatal care that has the potential to make an impact on preterm birth. SYSTEMATIC REVIEW REGISTRATION: PROSPERO on 25 of May, 2020 with registration number CRD42020177386.

Vaginal progesterone for prevention of preterm birth in asymptomatic high-risk women with a normal cervical length: a systematic review and meta-analysis protocol.

BACKGROUND: Preterm birth (PTB) is estimated to affect 14.9 million babies globally every year. Global rates of PTB continue to increase from 9.8 to 10.6% over a 15-year period from 2000 to 2014. Vaginal progesterone is commonly used by clinicians as a prevention strategy, with recent evidence affirming the benefit of vaginal (micronised) progesterone to prevent PTB in women with a shortened cervix (< 25 mm). Given the low incidence of a short cervix at mid-gestation in high-risk populations further evidence is required. The objective of this review is to determine if vaginal progesterone reduces spontaneous preterm birth (sPTB) before 37 weeks in asymptomatic high-risk women with a singleton pregnancy with a normal mid-gestation cervical length. METHODS: Studies will be sourced from MEDLINE, Embase and Cochrane Register of Trials (CENTRAL) from their inception onwards with the search terms 'progesterone' and 'preterm birth'. Studies will be screened and included if they assess vaginal progesterone compared to placebo in women with a normal cervical length. The primary outcome will be sPTB < 37 weeks, with secondary outcomes of sPTB < 34 weeks. Two independent reviewers will conduct study screening at abstract and full text level, data extraction and risk of bias assessment with disagreements resolved by an experienced researcher. The Mantel-Haenszel statistical method and random effects analysis model will be used to produce treatment effect odds ratios and corresponding 95% confidence intervals. DISCUSSION: This review will assess the current body of evidence and provide clarity regarding the potential benefits and best practice of use of vaginal progesterone in asymptomatic women with high-risk singleton pregnancies and normal cervical length. TRIAL REGISTRATION: PROSPERO CRD42020152051.

Does aspirin prescribed to women deemed high risk for preterm pre-eclampsia at 11-13+6 weeks gestation affect the prevalence of small for gestational age neonates?

BACKGROUND: Aspirin has been shown to reduce prevalence of both early-onset pre-eclampsia (ePET) and fetal growth restriction (FGR). AIMS: To determine whether aspirin prescribed for risk of ePET reduces the prevalence of small for gestational age (SGA) neonates. MATERIAL AND METHODS: Two prospective cohorts were consecutively recruited in a large university hospital in Sydney. The Observational cohort (April 2010 to March 2012) validated an algorithm for ePET screening, where risk for ePET was modelled on history, mean arterial pressure, uterine artery pulsatility index and pregnancy-associated plasma protein A. The Interventional cohort (April 2012 to December 2017) were screened and allocated women at high risk of developing ePET to aspirin 150 mg. The prevalence of preterm and term SGA was compared using regression analysis. RESULT: There were 3013 and 8424 women screened in the Observational and Interventional cohorts respectively. Women who screened high risk for ePET were three to four times more likely to give birth to a neonate classified as SGA in the Observational (6.8% vs 1.9%) and Interventional cohorts (6.0% vs 1.8%). In women who screened high risk, there were no statistically significant differences in the prevalence of SGA neonates (6.6% vs 6.0%; adjusted odds ratio 0.84 (0.50-1.42)) in women who received aspirin compared to women who did not. CONCLUSIONS: Women who screen high risk for ePET have an increased chance of delivering an SGA infant. A reduction in the prevalence of SGA neonates when aspirin was prescribed to women who screened high risk for ePET did not reach clinical significance in our cohort.

The discovery and validation of colorectal cancer biomarkers.

Colorectal cancer is currently the third most common malignancy in the world. Patients have excellent prognosis following surgical resection if their tumour is still localized at diagnosis. By contrast, once the tumour has started to metastasize, prognosis is much poorer. Accurate early detection can therefore significantly reduce the mortality from this disease. However, current tests either lack the required sensitivity and selectivity or are costly and invasive. Improved biomarkers, or panels of biomarkers, are therefore urgently required. We have addressed current screening strategies and potential protein biomarkers that have been proposed. The role of both discovery and hypothesis-driven proteomics approaches for biomarker discovery and validation is discussed. Using such approaches we show how multiple reaction monitoring (MRM) can be successfully developed and used for quantitative multiplexed analysis of potential faecal biomarkers.