Effectiveness of progesterone, cerclage and pessary for preventing preterm birth in singleton pregnancies: a systematic review and network meta-analysis

Screening and prevention of preterm birth: how is it done in clinical practice?

Objective

To ascertain how screening for preterm birth is performed among obstetricians working in public and private practice in a middle-income country.

Methods

Cross-sectional study of 265 obstetrician-gynecologists employed at public and private facilities. An online questionnaire was administered, with items designed to collect data on prematurity screening and prevention practices.

Results

The mean age of respondents was 44.5 years; 78.5% were female, and 97.7% had completed a medical residency program. Universal screening (i.e., by ultrasound measurement of cervical length) was carried out by only 11.3% of respondents in public practice; 43% request transvaginal ultrasound if the manual exam is abnormal, and 74.6% request it in pregnant women with risk factors for preterm birth. Conversely, 60.7% of respondents in private practice performed universal screening. This difference in screening practices between public and private practice was highly significant (p < 0.001). Nearly all respondents (90.6%) reported prescribing vaginal progesterone for short cervix.

Conclusion

In the setting of this study, universal ultrasound screening to prevent preterm birth was used by just over half of doctors in private practice. In public facilities, screening was even less common. Use of vaginal progesterone in cervical shortening was highly prevalent. There is an unmet need for formal protocols for screening and prevention of preterm birth in middle-income settings.

Strategies for Safeguarding High-Risk Pregnancies From Preterm Birth: A Narrative Review

Preterm birth is the delivery of a live fetus before the 37th week of gestation. Preterm birth may stem from various factors, including premature rupture of membranes, spontaneous preterm labor, or medically induced circumstances. Premature delivery can result in serious and long-lasting difficulties even for infants who survive, as it is the leading cause of death for infants under five years old. Numerous nations have implemented initiatives to detect and track pregnant women who may give birth before their due date. Numerous therapies are available to protect these at-risk groups from the devastating effects of premature delivery, given the complex nature of preterm birth risk factors. Among the preventive measures, prophylactic progesterone appears to hold significant promise, while cervical cerclage proves effective in cases of cervical insufficiency. Conversely, pessaries show no discernible beneficial effects in reducing the risk of preterm birth. Regular antenatal visits are imperative for frequent patient evaluation and screening for potential risk factors. Adopting a healthy lifestyle can influence the risk of developing preeclampsia, with regular physical activity, a fiber-rich diet, and smoking cessation serving to mitigate the risk of preterm birth. The efficacy of bed rest in preventing preterm birth remains inconclusive due to insufficient evidence. This study aims to explore various preventive strategies for averting premature birth in high-risk women.

How do network meta-analyses address intransitivity when assessing certainty of evidence: a systematic survey

OBJECTIVES

To describe how systematic reviews with network meta-analyses (NMAs) that used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) NMA approach addressed intransitivity when assessing certainty of evidence.

DESIGN

Systematic survey.

DATA SOURCES

Medline, Embase and Cochrane Database of Systematic Reviews from September 2014 to October 2022.

ELIGIBILITY CRITERIA

Systematic reviews of randomised controlled trials with aggregate data NMAs that used the GRADE NMA approach for assessing certainty of evidence.

DATA EXTRACTION AND SYNTHESIS

We documented how reviewers described methods for addressing intransitivity when assessing certainty of evidence, how often they rated down for intransitivity and their explanations for rating down.

RESULTS

Of the 268 eligible systematic reviews, 44.8% (120/268) mentioned intransitivity when describing methods for assessing the certainty of evidence. Of these, 28.3% (34/120) considered effect modifiers and from this subset, 67.6% (23/34) specified the effect modifiers; however, no systematic review noted how they chose the effect modifiers. 15.0% (18/120) mentioned looking for differences between the direct comparisons that inform the indirect estimate. No review specified a threshold for difference in effect modifiers between the direct comparisons that would lead to rating down for intransitivity. Reviewers noted rating down indirect evidence for intransitivity in 33.1% of systematic reviews, and noted intransitivity for network estimates in 23.0% of reviews. Authors provided an explanation for rating down for intransitivity in 59.6% (31/52) of the cases in which they rated down. Of the 31 in which they provided an explanation, 74.2% (23/31) noted they detected differences in effect modifiers and 67.7% (21/31) specified in what effect modifiers they detected differences.

CONCLUSIONS

A third of systematic reviews with NMAs using the GRADE approach rated down for intransitivity. Limitations in reporting of methods to address intransitivity proved considerable. Whether the problem is that reviewers neglected to address rating down for transitivity at all, or whether they did consider but not report, is not clear. At minimum systematic reviews with NMAs need to improve their reporting practices regarding intransitivity; it may well be that they need to improve their practice in transitivity assessment. How to best address intransitivity may remain unclear for many reviewers thus additional GRADE guidance providing practical instructions for addressing intransitivity may be desirable.

How to screen the cervix and reduce the risk of spontaneous preterm birth in asymptomatic women without a prior preterm birth

Preterm birth (PTB) is a leading cause of perinatal morbidity and mortality globally. PTB rates have increased in South Korea despite reduction in birth rates. A history of PTB is a strong predictor of subsequent PTB and screening of cervical length between 16 0/7 weeks and 24 0/7 weeks of gestation is recommended in women with a singleton pregnancy and a prior spontaneous PTB. However, the prediction and prevention of spontaneous PTBs in women without a prior PTB remain a matter of debate. The scope of this review article comprises cervical screening and prevention strategies for PTB in asymptomatic women without a prior PTB, based on recent evidence and guidelines.

Interventions for the prevention of spontaneous preterm birth: a scoping review of systematic reviews

BACKGROUND

Globally, 11% of babies are born preterm each year. Preterm birth (PTB) is a leading cause of neonatal death and under-five mortality and morbidity, with lifelong sequelae in those who survive. PTB disproportionately impacts low/middle-income countries (LMICs) where the burden is highest.

OBJECTIVES

This scoping review sought to the evidence for interventions that reduce the risk of PTB, focusing on the evidence from LMICs and describing how context is considered in evidence synthesis.

DESIGN

We conducted a scoping review, to describe this wide topic area. We searched five electronic databases (2009-2020) and contacted experts to identify relevant systematic reviews of interventions to reduce the risk of PTB. We included published systematic reviews that examined the effectiveness of interventions and their effect on reducing the risk of PTB. Data were extracted and is described narratively.

RESULTS

139 published systematic reviews were included in the review. Interventions were categorised as primary or secondary. The interventions where the results showed a greater effect size and consistency across review findings included treatment of syphilis and vaginal candidiasis, vitamin D supplementation and cervical cerclage. Included in the 139 reviews were 1372 unique primary source studies. 28% primary studies were undertaken in LMIC contexts and only 4.5% undertaken in a low-income country (LIC) Only 10.8% of the reviews sought to explore the impact of context on findings, and 19.4% reviews did not report the settings or the primary studies.

CONCLUSION

This scoping review highlights the lack of research evidence derived from contexts where the burden of PTB globally is greatest. The lack of rigour in addressing contextual applicability within systematic review methods is also highlighted. This presents a risk of inappropriate and unsafe recommendations for practice within these contexts. It also highlights a need for primary research, developing and testing interventions in LIC settings.

Pregnancy outcomes in women with active anorexia nervosa: a systematic review

BACKGROUND

It is a common misconception that women with active anorexia nervosa (AN) are less likely to conceive. Pregnancies in women with AN are considered high risk. The purpose of this systematic review was to explore pregnancy complications in women with active AN, including maternal, fetal, and neonatal complications.

METHODS

The authors conducted a systematic review in accordance with PRISMA statement guidelines with stringent selection criteria to include studies on patients with active AN during pregnancy.

RESULTS

There were 21 studies included in our review. Anaemia, caesarean section, concurrent recreational substance use, intrauterine growth restriction, preterm birth, small-for-gestation (SGA) birth, and low birth weight were the most reported pregnancy complications in women with active AN, while the rates of gestational diabetes and postpartum haemorrhage were lower.

DISCUSSION

Women with active AN have a different profile of pregnancy complications comparing to malnourished women and women in starvation. We recommend early discussion with women diagnosed with AN regarding their fertility and pregnancy complications. We recommend clinicians to aim to improve physical and psychological symptoms of AN as well as correction of any nutritional deficiency ideally prior to conception. Management of pregnancies in women with active AN requires regular monitoring, active involvement of obstetricians and psychiatrist. Paediatric follow-up postpartum is recommended to ensure adequate feeding, wellbeing and general health of the infants. Psychiatric follow-up is recommended for mothers due to risk of worsening symptoms of AN during perinatal period.

A review of conventional and sustained-release formulations of oral natural micronized progesterone in obstetric indications

Background

Exogenous progesterone is a treatment option for obstetric indications associated with reduced progesterone activity. Oral natural micronized progesterone (NMP) is effective, although it requires multiple daily doses and may cause adverse events due to its active metabolites. A sustained-release formulation of NMP (NMP-SR) has been developed to overcome the limitations of conventional oral NMP.

Methods

This narrative review examines the available evidence for oral NMP and NMP-SR in several obstetric indications of interest.

Results

Literature searches identified 17 studies of oral NMP (luteal phase support during assisted reproduction, prevention of threatened miscarriage, prevention of preterm delivery), and clinical studies supporting use of NMP-SR (luteal phase support during intrauterine insemination, maintenance of high-risk pregnancy). Oral NMP was effective for luteal phase support during in vitro fertilization and intrauterine insemination, prevention of threatened miscarriage, and prevention of preterm delivery. NMP-SR was comparable to dydrogesterone for luteal phase support during intrauterine insemination and effectively maintained high-risk pregnancies. Oral NMP-SR was well tolerated.

Conclusions

By releasing progesterone gradually and circumventing first-pass metabolism, NMP-SR elicits the desired therapeutic effect with benefits over conventional oral NMP in terms of bioavailability, once-daily dosing and improved tolerability. Oral NMP-SR appears to be a valuable option for treating obstetric conditions associated with insufficient progesterone exposure.

Effects of vaginal microbiota and cervical cerclage on obstetric outcomes of twin pregnancies with cervical incompetence: a retrospective study

PURPOSE

To determine the role of vaginal microbiota in the efficacy of cervical cerclage in obstetric outcomes of twin pregnancies.

METHODS

This retrospective study enrolled 68 twin pregnant women diagnosed with cervical incompetence (CIC) and 68 twin pregnancies without CIC. The CIC group was further divided into two subgroups: cerclage group (n = 51) and non-cerclage group (n = 17), according to whether cervical cerclage was performed in the second trimester. Data of vaginal microbiota and obstetric outcomes were collected and compared.

RESULTS

Cervical incompetence had harmful effect on both pregnancy outcomes and vaginal microecology, characterized by earlier gestational week at delivery (30.3 ± 5.6 vs 35.6 ± 1.1, P < 0.001), a lower birth weight of newborns (OR 0.40; 95% CI 0.22-0.74), a higher vaginal pH value (OR 0.11; 95% CI 0.04-0.30) and a lower abundance of Lactobacillus (OR 0.34; 95% CI 0.17-0.70). In addition, compared with the vaginal microbiota after cerclage, less normal diversity of bacterial flora (OR 0.35; 95% CI 0.12-1.01), less Lactobacillus (OR 0.40; 95% CI 0.18-0.91) and more Gardnerella vaginalis (OR 18.92; 95% CI 2.38-150.35) appeared before cerclage. Besides, the unhealthy vaginal environment also had an unfavorable influence on the neonatal outcomes, increased neonatal mortality rate was observed in the group of vaginal pH > 4.5 (P < 0.05). Fortunately, compared with the non-cerclage group, the cerclage group had a longer interval from diagnosis to delivery (≥ 8 weeks) and more of the newborns' birth weight were not less than 1500 g (P < 0.05).

CONCLUSION

A healthy vaginal environment is essential to improve the obstetric outcome for twin pregnancies with cervical cerclage.

Guideline No. 401: Sonographic Cervical Length in Singleton Pregnancies: Techniques and Clinical Applications

OBJECTIVES

• To assess the association between sonography-derived cervical length measurement and preterm birth. • To describe the various techniques to measure cervical length using sonography. • To review the natural history of the short cervix. • To review the clinical uses, predictive ability, and utility of sonography-measured short cervix.

OUTCOMES

Reduction in rates of prematurity and/or better identification of those at risk, as well as possible prevention of unnecessary interventions.

INTENDED USERS

Clinicians involved in the obstetrical management or cervical imaging of patients at increased risk of a short cervix.

TARGET POPULATION

Women at increased risk of a short cervix or at risk of preterm birth.

EVIDENCE

Literature published up to June 2019 was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary and key words (preterm labour, ultrasound, cervix, cervical insufficiency, transvaginal, transperineal, cervical length, fibronectin). Results were restricted to general and systematic reviews, randomized controlled trials, controlled clinical trials, and observational studies. There were no date or language restrictions. Grey (unpublished) literature was identified through searching the websites of health technology assessment agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence and this guideline were reviewed by the Diagnostic Imaging Committee of the Society of Obstetricians and Gynaecologists of Canada, and the recommendations were made and graded according to the rankings of the Canadian Task Force on Preventive Health Care (Online Appendix Table A1).

BENEFITS, HARMS, COSTS

Preterm birth is a leading cause of perinatal morbidity and mortality. Use of the sonographic technique reviewed in this guideline may help identify women at risk of preterm birth and, in some circumstances, lead to interventions that may reduce the rate of preterm birth. SUMMARY STATEMENTS (CANADIAN TASK FORCE ON PREVENTIVE HEALTH CARE GRADING IN PARENTHESES): RECOMMENDATIONS (CANADIAN TASK FORCE ON PREVENTIVE HEALTH CARE GRADING IN PARENTHESES).

Use of the Arabin pessary in women at high risk for preterm birth: long-term experience at a single tertiary center in Malaysia

Background

Spontaneous preterm birth is a global issue that contributed to perinatal morbidities and mortalities worldwide. The study aimed to describe the experience at UKM Medical Center in managing women at high risk for spontaneous preterm birth using the Arabin pessary.

Methods

This is a retrospective observational study involving 58 pregnancies from 1st January 2013 to 31st December 2019. Inclusion criteria were previous mid-trimester miscarriage and/or preterm birth, previous cervical surgery or short cervical length on routine sonogram. The demographic data, characteristics of each pregnancy and details of outcomes and management were described.

Results

The majority of women were Malay with mean age and body mass index of 32.9 ± 4.2 years and 27.1 ± 6.3 kg/m² respectively. The most frequent indications for Arabin pessary insertion were previous mid-trimester miscarriage (46.4%) and early preterm birth (17.2%). A total of 73.4% of these women had the pessary inserted electively at a mean cervical length of 31.6 ± 9.1 mm at median gestation of 15.0 weeks. They were managed as outpatient (56.9%), inpatient (24.1%) or mixed (19.0%) with combination of progestogen (81.0%) and 53.4% received antenatal corticosteroids. Spontaneous preterm birth at or more than 34 weeks gestation occurred in 74.1% with birthweight at or more than 2000 g (82.4%). Despite cervical funneling in 12 women (20.7%), 66.7% delivered at or later than 34 weeks gestation and 2 (16.7%) resulted in miscarriage.

Conclusions

Insertion of the Arabin pessary is beneficial to prevent spontaneous preterm birth in pregnant women who are at high risk. In particular, early insertion and close monitoring allows the best possible outcomes.

Trial registration

This study was retrospectively registered with ClinicalTrials.gov (NCT04638023) on 20/11/2020.

Occupational exposure to whole body vibrations and birth outcomes - A nationwide cohort study of Swedish women

BACKGROUND

More women in reproductive ages are entering occupations where exposure to whole body vibrations (WBV) is common (e.g. in transportation and construction). Previous studies based on self-assessed exposure suggest increased risks of adverse birth outcomes, but it is unclear at what exposure levels and if the current exposure guidelines are appropriate during pregnancy.

OBJECTIVES

To investigate whether occupational WBV-exposure increases the risk of preterm birth, low birth weight, and/or small-for-gestational age, in a large, nationwide, prospective, cohort study.

DESIGN

The Fetal Air Pollution Exposure cohort (FAIR) was formed by merging data from multiple, national registers, and the present study includes singletons born 1994-2014 to working women in Sweden (n = 1,091,080 births). WBV-exposure was assessed quantitatively using a job-exposure matrix based on measurements, and calculated odds ratios were adjusted for potential confounders such as smoking and BMI, and other occupational exposures like noise, combustion particles, and physically and psychologically strenuous work. Data on absence from work (full-/part time, sick leave, parental leave, etc.) was also used.

RESULTS

Exposure to WBV during pregnancy, among women with low absence from work (n = 476,419), was associated with an increased risk of preterm birth, below the occupational exposure limit (1.15 m/s²). Compared to unexposed mothers, the OR was 1.38 (95% CI: 1.05, 1.83) for exposure ≥0.5 m/s², corresponding to an increase from 47/1000 cases to 65/1000 cases. No increased risk was found for small-for-gestational age.

CONCLUSIONS

Exposure to WBV was associated with an increased risk of preterm birth. The results suggest that the current permissible exposure and action levels for WBV-exposure do not adequately protect pregnant women with continuous exposure.

Association of Cerclage with Composite Adverse Outcomes among Women Delivered at 36 Weeks or Later

OBJECTIVE

This study aimed to compare the maternal and neonatal adverse outcomes among singletons delivered at 36 weeks or later with cerclage during index pregnancy versus those without cerclage.

STUDY DESIGN

This retrospective cohort study utilized the U.S. vital statistics datasets from 2011 to 2013. Inclusion criteria were women with nonanomalous singletons, with and without cerclage placement, without diabetes or hypertensive disorders, and delivered at 36 to 41 weeks. The coprimary outcomes were composite maternal and neonatal adverse outcomes. Composite maternal adverse outcome included admission to intensive care unit, maternal transfusion, ruptured uterus, unplanned hysterectomy, or unplanned operating room procedure. Composite neonatal adverse outcome included Apgar score less than 5 at 5 minutes, assisted ventilation for more than 6 hours, neonatal seizure, birth injury, or neonatal death. Secondary outcomes were chorioamnionitis and cesarean delivery. Multivariable Poisson's regression models with error variance were used while adjusting for confounders. Adjusted relative risk (aRR) with 95% confidence intervals (CIs) were calculated.

RESULTS

Of the 8,508,228 women who met inclusion criteria, 0.2% had a cerclage and reached 36 weeks. Composite maternal (aRR: 2.04; 95% CI: 1.76-2.36) and neonatal (aRR: 1.28; 95% CI: 1.11-1.47) adverse outcomes were significantly higher among those with cerclage than those without cerclage. Chorioamnionitis (aRR: 1.47; 95% CI: 1.30-1.67) and cesarean delivery (aRR: 1.10; 95% CI: 1.08-1.12) were also significantly higher in women with cerclage than those without cerclage.

CONCLUSION

There is an association between increased composite maternal and neonatal adverse outcomes among women with cerclage who delivered at 36 to 41 weeks as compared with those without cerclage.

KEY POINTS

· Cerclage is associated with increased composite maternal adverse outcome in women at 36-41 weeks.. · Cerclage is associated with increased composite neonatal adverse outcome in women at 36-41 weeks.. · Increased chorioamnionitis and cesarean delivery rates are associated with cerclage in women at 36-41 weeks..

Cervical cerclage application algorithm in continued cervical shortening cases despite vaginal progesterone

OBJECTIVE

The aim of this study is evaluation of pregnancy outcomes of the asymptomatic cases with vaginal progesterone treatment for the 20-30 mm cervical length detected in the transvaginal ultrasonography for fetal abnormality screening and cervical cerclage after cervical length detected <20 mm in weekly cervical length measures; and present the treatment algorithm of progesterone treatment combined with cervical cerclage application.

METHODS

Patients who have the inclusion criteria and cervical length more than 30 mm were categorized as group 1(n = 1948). Group 2 were included patients with cervical length shorter than 30 mm (n = 95). All patients of group 2 started to use vaginal natural progesterone 400 mg/day(n = 87). Pregnancies which progressed with cervical length above 20 mm were continued vaginal progesterone until 34. Gestational week and they were named as group 2A (n = 78). Cervical cerclage were applied to patients with cervical length below than 20 mm measured via transvaginal ultrasonography and they were categorized as group 2B (n = 9).

RESULTS

Excluding 8 cases (8.42 %) which cervical cerclage were applied, 87 patients were administered vaginal progesterone and in 9 cases (10.34 %) cervical shortening were continued despite progesterone treatment. Four out of these nine cases (44.44 %) had cervical cerclage and their deliveries were delayed after 34 th gestational week. Vaginal progesterone treatment prevented cervical shortening in 89.66 % of patients who had cervical length between 20-30 mm and out of these patients.

CONCLUSION

Cervical cerclage application algorithm in continued cervical shortening cases despite vaginal progesterone is beneficial to delay the delivery after 34 th gestational week and related to low complication rate.

Regarding the evidence-based use of micronized progesterone

An issue of habitual miscarriage poses a high social importance especially during COVID-19 pandemic. Meanwhile, healthcareworkers faced a mass media campaign against using micronized progesterone upon habitual miscarriage, which, as viewed by us, displays signs of prejudiced data manipulation and may disorient practitioners. In this Letter we provide objective information on accumulated data regarding gestagenes efficacy and safety. We invoke healthcare professionals to make decisions deserving independent primary source trust presented by original scientific papers published in peer-reviewed journals, clinical recommendations proposed by professional medical communities as well as treatment standards and protocols.

Maternal morbidity after early preterm delivery (23-28 weeks)

BACKGROUND

Previous research has focused mainly on neonatal outcomes associated with preterm and periviable delivery, but maternal outcomes with preterm delivery are less well described.

OBJECTIVE

This study aimed to determine if early preterm delivery results in an increase in maternal morbidity.

STUDY DESIGN

This is a retrospective cohort study conducted at a tertiary care center over a 5-year time period. Subjects were women identified by review of neonatal intensive care unit admission logs. Women were included if they delivered between 23 0/7 and 28 6/7 weeks' gestation and their neonate was admitted to the neonatal intensive care unit. The prevalence of maternal morbidities was assessed, including blood transfusion, maternal infection, placental abruption, postpartum depression or positive depression screen, hemorrhage, and prolonged maternal postpartum hospitalization. A composite outcome comprising blood transfusion, maternal infectious morbidity, placental abruption, and postpartum depression was developed. Outcomes for women who delivered between 23 0/7 and 25 6/7 weeks' gestation (early group) and 26 0/7 and 28 6/7 weeks' gestation (late group) were compared. Multivariate logistic regression analysis was performed to evaluate contributors to the composite morbidity, controlling for confounding.

RESULTS

A total of 82 women met the inclusion criteria: 38 in the early group and 44 in the late group. Maternal demographics were similar between the groups. The early group was significantly more likely to experience composite maternal morbidity (60.5% vs 27.3%; P=.004) and infection (42.1% vs 13.6%; P=.006). Regression analysis determined that delivery at a later gestational age was associated with lower rates of composite morbidity (odds ratio, 0.6; 95% confidence interval, 0.41-0.83).

CONCLUSION

In this study, data suggest that maternal morbidity is higher with delivery at periviable gestational ages. Composite morbidity and maternal infection were more frequent in women who delivered at less than 26 weeks' gestation. The management of women at risk for delivery at early gestational ages should include a discussion of increased maternal complications.

Role of sex hormones in cervical changes in a cervical excision-related preterm delivery mouse model

Progesterone and oestrogen play important roles during parturition; however, their roles in the uterine cervix during preterm labour and delivery are unknown. We evaluated the serum progesterone and oestrogen levels and changes in their receptors (PR and ER) in the cervix in a cervical excision-associated preterm delivery mouse model. Adult female C57BL/6 mice were divided into four groups: sham, cervical excision (Ex), lipopolysaccharide (LPS) and Ex + LPS. Mating was permitted at 3 weeks post-Ex. On gestation day 16, mice were administered LPS intrauterine (100 µg/100 µL/mouse) or physiological saline (100 µL) via laparotomy. Uterine cervices and blood were sampled immediately postpartum. As a result, epithelial PR and muscular ERα were down- and upregulated, respectively, in the proximal cervix in Ex + LPS group compared to in the sham group. These results indicate that unique sex hormone effects are exerted on the uterine cervix during cervical excision-associated spontaneous preterm labour and delivery.Impact statementWhat is already known on this subject? Preterm and term parturition require the withdrawal of progesterone and the activation of oestrogen in the uterine body and systemic levels. However, we have little understanding of the role of the sex hormones in the uterine cervix.What do the results of this study add? Increased ERα-to-PR expression ratio in the proximal cervix was associated with preterm labour and delivery. ERα expression in the smooth muscle layer of the proximal cervix was higher and PR expression in the proximal cervix epithelium was lower during preterm labour and delivery.What are the implications of these findings for clinical practice and/or further research? This study revealed the differences between the roles of sex hormones and their receptors in epithelial and muscle layers of proximal and distal cervices in preterm labour and delivery.

Cervical pessary for preventing preterm birth in singletons and twin pregnancies: an update systematic review and meta-analysis

Objectives: To evaluate the effectiveness of cervical pessary in preventing preterm birth (PTB) and improving perinatal outcomes among singleton and twin pregnancies.Methods: Electronic databases were systematically searched from their inception until 14 March 2019. Randomized clinical trials comparing the effectiveness of cervical pessary placement with expectant management were included. The primary outcome was the incidence of PTB <34 weeks.Results: Thirteen studies were included, involving eight studies about singleton and six studies about twin pregnancies. For singleton pregnancies with short cervical length, cervical pessary, comparing with expectant treatment, seemed have no effectiveness in preventing PTB <34 weeks (relative risk, 95% confidence interval, 0.73, 0.42-1.28), <37 weeks (0.69, 0.43-1.09), and <28 weeks (0.79, 0.42-1.48); while for twin pregnancies with short cervical length, cervical pessary also did not reduce the risk of PTB <34 weeks (0.81, 0.49-1.35), <37 weeks (0.93, 0.83-1.05), and <28 weeks (0.72, 0.38-1.38). However, cervical pessary seemed have the effectiveness of reducing the risk of spontaneous PTB <28 weeks (0.50, 0.25-0.99) and low birth weight (<1500 g) (0.68, 0.50-0.94) among twin pregnancies with short cervical length. In addition, cervical pessary increased the rate of vaginal discharge and did not improve perinatal outcomes among both singleton and twin pregnancies.Conclusions: Comparing with the expectant treatment, the effectiveness of cervical pessary for reducing the risk of PTB remains uncertain. Additional trials are warranted to further evaluate the effectiveness of cervical pessary.

Trace biomarkers associated with spontaneous preterm birth from the maternal serum metabolome of asymptomatic nulliparous women - parallel case-control studies from the SCOPE cohort

Prediction of spontaneous preterm birth (sPTB) in asymptomatic women remains a great challenge; accurate and reproducible screening tools are still not available in clinical practice. We aimed to investigate whether the maternal serum metabolome together with clinical factors could be used to identify asymptomatic women at risk of sPTB. We conducted two case-control studies using gas chromatography-mass spectrometry to analyse maternal serum samples collected at 15- and 20-weeks' gestation from 164 nulliparous women from Cork, and 157 from Auckland. Smoking and vaginal bleeding before 15 weeks were the only significant clinical predictors of sPTB for Auckland and Cork subsets, respectively. Decane, undecane, and dodecane were significantly associated with sPTB (FDR < 0.05) in the Cork subset. An odds ratio of 1.9 was associated with a one standard deviation increase in log (undecane) in a multiple logistic regression which also included vaginal bleeding as a predictor. In summary, elevated serum levels of the alkanes decane, undecane, and dodecane were associated with sPTB in asymptomatic nulliparous women from Cork, but not in the Auckland cohort. The association is not strong enough to be a useful clinical predictor, but suggests that further investigation of the association between oxidative stress processes and sPTB risk is warranted.

Preterm Birth: A Narrative Review of the Current Evidence on Nutritional and Bioactive Solutions for Risk Reduction

Preterm birth (PTB) (<37 weeks of gestation) is the leading cause of newborn death and a risk factor for short and long-term adverse health outcomes. Most cases are of unknown cause. Although the mechanisms triggering PTB remain unclear, an inappropriate increase in net inflammatory load seems to be key. To date, interventions that reduce the risk of PTB are effective only in specific groups of women, probably due to the heterogeneity of its etiopathogenesis. Use of progesterone is the most effective, but only in singleton pregnancies with history of PTB. Thus, primary prevention is greatly needed and nutritional and bioactive solutions are a promising alternative. Among these, docosahexaenoic acid (DHA) is the most promising to reduce the risk for early PTB. Other potential nutrient interventions include the administration of zinc (possibly limited to populations with low nutritional status or poor zinc status) and vitamin D; additional preliminary evidence exists for vitamin A, calcium, iron, folic acid, combined iron-folate, magnesium, multiple micronutrients, and probiotics. Considering the public health relevance of PTB, promising interventions should be studied in large and well-designed clinical trials. The objective of this review is to describe, summarize, and discuss the existing evidence on nutritional and bioactive solutions for reducing the risk of PTB.

Previous Adverse Outcome of Term Pregnancy and Risk of Preterm Birth in Subsequent Pregnancy

Objective Evaluate risk of preterm birth (PTB, < 37 completed weeks' gestation) among a population of women in their second pregnancy with previous full term birth but other adverse pregnancy outcome. Methods The sample included singleton live born infants between 2007 and 2012 in a birth cohort file maintained by the California Office of Statewide Health Planning and Development. The sample was restricted to women with two pregnancies resulting in live born infants and first birth between 39 and 42 weeks' gestation. Logistic regression was used to calculate the risk of PTB in the second birth for women with previous adverse pregnancy outcome including: small for gestational age (SGA) infant, preeclampsia, placental abruption, or neonatal death (≤ 28 days). Risks were adjusted for maternal factors recorded for second birth. Results The sample included 133,622 women. Of the women with any previous adverse outcome, 4.7% had a PTB while just 3.0% of the women without a previous adverse outcome delivered early (relative risk adjusted for maternal factors known at delivery 1.4, 95% CI 1.3-1.5). History of an SGA infant, placental abruption, or neonatal death increased the adjusted risk of PTB in their second birth by 1.5-3.7-fold. History of preeclampsia did not elevate the risk of a preterm birth in the subsequent birth. Conclusions for Practice The findings indicate that women with previous SGA infant, placental abruption, or neonatal death, despite a term delivery, may be at increased risk of PTB in the subsequent birth. These women may be appropriate participates for future interventions aimed at reduction in PTB.

Assessment of Uterocervical Angle Width as a Predictive Factor of Preterm Birth: A Systematic Review of the Literature

Background

Uterocervical angle (UCA) has been recently proposed as a potential marker that could accurately predict preterm birth (PTB). The purpose of the present systematic review is to accumulate current evidence and provide directions for future research.

Materials and Methods

We used the Medline (1966–2018), Scopus (2004–2018), Clinicaltrials.gov (2008–2018), EMBASE (1980-2018), Cochrane Central Register of Controlled Trials CENTRAL (1999-2018), and Google Scholar (2004-2018) databases in our search.

Results

Eleven studies were finally included in the present systematic review that evaluated data from 3,018 women. The significant heterogeneity in terms of outcome reporting and outcome reporting measures (use of optimal cut-off values) precluded meta-analysis. However, existing data support that second trimester UCA measurement might be used as a predictive factor of PTB <34 weeks, as at least two studies in unselected singleton pregnancies and two studies in pregnancies with an ultrasonographically shortened cervix seem to support this hypothesis. The most commonly reported cut-off values were 105° and 95°.

Conclusions

UCA measurement during the second trimester of pregnancy may be a useful method of determining women at risk of delivering preterm. However, more studies are needed to assess the reproducibility of these findings and reach conclusive evidence.

Interventions during pregnancy to prevent preterm birth: an overview of Cochrane systematic reviews

BACKGROUND

Preterm birth (PTB) is a major factor contributing to global rates of neonatal death and to longer-term health problems for surviving infants. Both the World Health Organization and the United Nations consider prevention of PTB as central to improving health care for pregnant women and newborn babies. Current preventative clinical strategies show varied efficacy in different populations of pregnant women, frustrating women and health providers alike, while researchers call for better understanding of the underlying mechanisms that lead to PTB.

OBJECTIVES

We aimed to summarise all evidence for interventions relevant to the prevention of PTB as reported in Cochrane systematic reviews (SRs). We intended to highlight promising interventions and to identify SRs in need of an update.

METHODS

We searched the Cochrane Database of Systematic Reviews (2 November 2017) with key words to capture any Cochrane SR that prespecified or reported a PTB outcome. Inclusion criteria focused on pregnant women without signs of preterm labour or ruptured amniotic membranes. We included reviews of interventions for pregnant women irrespective of their risk status. We followed standard Cochrane methods.We applied GRADE criteria to evaluate the quality of SR evidence. We assigned graphic icons to classify the effectiveness of interventions as: clear evidence of benefit; clear evidence of harm; clear evidence of no effect or equivalence; possible benefit; possible harm; or unknown benefit or harm. We defined clear evidence of benefit and clear evidence of harm to be GRADE moderate- or high-quality evidence with a confidence interval (CI) that does not cross the line of no effect. Clear evidence of no effect or equivalence is GRADE moderate- or high-quality evidence with a narrow CI crossing the line of no effect. Possible benefit and possible harm refer to GRADE low-quality evidence with a clear effect (CI does not cross the line of no effect) or GRADE moderate- or high-quality evidence with a wide CI. Unknown harm or benefit refers to GRADE low- or very low-quality evidence with a wide CI.

MAIN RESULTS

We included 83 SRs; 70 had outcome data. Below we highlight key results from a subset of 36 SRs of interventions intended to prevent PTB.

OUTCOME

preterm birthClear evidence of benefitFour SRs reported clear evidence of benefit to prevent specific populations of pregnant women from giving birth early, including midwife-led continuity models of care versus other models of care for all women; screening for lower genital tract infections for pregnant women less than 37 weeks' gestation and without signs of labour, bleeding or infection; and zinc supplementation for pregnant women without systemic illness. Cervical cerclage showed clear benefit for women with singleton pregnancy and high risk of PTB only.Clear evidence of harmNo included SR reported clear evidence of harm.No effect or equivalenceFor pregnant women at high risk of PTB, bedrest for women with singleton pregnancy and antibiotic prophylaxis during the second and third trimester were of no effect or equivalent to a comparator.Possible benefitFour SRs found possible benefit in: group antenatal care for all pregnant women; antibiotics for pregnant women with asymptomatic bacteriuria; pharmacological interventions for smoking cessation for pregnant women who smoke; and vitamin D supplements alone for women without pre-existing conditions such as diabetes.Possible harmOne SR reported possible harm (increased risk of PTB) with intramuscular progesterone, but this finding is only relevant to women with multiple pregnancy and high risk of PTB. Another review found possible harm with vitamin D, calcium and other minerals for pregnant women without pre-existing conditions.

OUTCOME

perinatal deathClear evidence of benefitTwo SRs reported clear evidence of benefit to reduce pregnant women's risk of perinatal death: midwife-led continuity models of care for all pregnant women; and fetal and umbilical Doppler for high-risk pregnant women.Clear evidence of harmNo included SR reported clear evidence of harm.No effect or equivalenceFor pregnant women at high risk of PTB, antibiotic prophylaxis during the second and third trimester was of no effect or equivalent to a comparator.Possible benefitOne SR reported possible benefit with cervical cerclage for women with singleton pregnancy and high risk of PTB.Possible harmOne SR reported possible harm associated with a reduced schedule of antenatal visits for pregnant women at low risk of pregnancy complications; importantly, these women already received antenatal care in settings with limited resources.

OUTCOMES

preterm birth and perinatal deathUnknown benefit or harmFor pregnant women at high risk of PTB for any reason including multiple pregnancy, home uterine monitoring was of unknown benefit or harm. For pregnant women at high risk due to multiple pregnancy: bedrest, prophylactic oral betamimetics, vaginal progesterone and cervical cerclage were all of unknown benefit or harm.

AUTHORS' CONCLUSIONS

Implications for practiceThe overview serves as a map and guide to all current evidence relevant to PTB prevention published in the Cochrane Library. Of 70 SRs with outcome data, we identified 36 reviews of interventions with the aim of preventing PTB. Just four of these SRs had evidence of clear benefit to women, with an additional four SRs reporting possible benefit. No SR reported clear harm, which is an important finding for women and health providers alike.The overview summarises no evidence for the clinically important interventions of cervical pessary, cervical length assessment and vaginal progesterone because these Cochrane Reviews were not current. These are active areas for PTB research.The graphic icons we assigned to SR effect estimates do not constitute clinical guidance or an endorsement of specific interventions for pregnant women. It remains critical for pregnant women and their healthcare providers to carefully consider whether specific strategies to prevent PTB will be of benefit for individual women, or for specific populations of women.Implications for researchFormal consensus work is needed to establish standard language for overviews of reviews and to define the limits of their interpretation.Clinicians, researchers and funders must address the lack of evidence for interventions relevant to women at high risk of PTB due to multiple pregnancy.

Prevention of Prematurity: Advances and Opportunities

Preterm birth (PTB) rate varies widely and has significant racial and ethnic disparities. Although causal mechanisms are ill understood, socioenvironment, phenotype, and genotype provide insight into pathways for preventing PTB. Data suggest varied response to current medical interventions is explicable Approved by underlying pharmacogenomics. Currently, prevention focuses on minimizing iatrogenic PTB and risk reduction especially in those with prior PTB using proven medical and public health strategies. In the future, preventive approaches will be based on better understanding of sociodemography, nutrition, lifestyles, and underlying individual genetic and epigenetic variation. Statistical approaches and "big-data" models are critical in future study.

Prediction of preterm birth with and without preeclampsia using mid-pregnancy immune and growth-related molecular factors and maternal characteristics

OBJECTIVE

To evaluate if mid-pregnancy immune and growth-related molecular factors predict preterm birth (PTB) with and without (±) preeclampsia.

STUDY DESIGN

Included were 400 women with singleton deliveries in California in 2009-2010 (200 PTB and 200 term) divided into training and testing samples at a 2:1 ratio. Sixty-three markers were tested in 15-20 serum samples using multiplex technology. Linear discriminate analysis was used to create a discriminate function. Model performance was assessed using area under the receiver operating characteristic curve (AUC).

RESULTS

Twenty-five serum biomarkers along with maternal age <34 years and poverty status identified >80% of women with PTB ± preeclampsia with best performance in women with preterm preeclampsia (AUC = 0.889, 95% confidence interval (0.822-0.959) training; 0.883 (0.804-0.963) testing).

CONCLUSION

Together with maternal age and poverty status, mid-pregnancy immune and growth factors reliably identified most women who went on to have a PTB ± preeclampsia.

Bitter taste receptors as targets for tocolytics in preterm labor therapy

Preterm birth (PTB) is the leading cause of neonatal mortality and morbidity, with few prevention and treatment options. Uterine contraction is a central feature of PTB, so gaining new insights into the mechanisms of this contraction and consequently identifying novel targets for tocolytics are essential for more successful management of PTB. Here we report that myometrial cells from human and mouse express bitter taste receptors (TAS2Rs) and their canonical signaling components (i.e., G-protein gustducin and phospholipase C β2). Bitter tastants can completely relax myometrium precontracted by different uterotonics. In isolated single mouse myometrial cells, a phenotypical bitter tastant (chloroquine, ChQ) reverses the rise in intracellular Ca2+ concentration ([Ca2+]i) and cell shortening induced by uterotonics, and this reversal effect is inhibited by pertussis toxin and by genetic deletion of α-gustducin. In human myometrial cells, knockdown of TAS2R14 but not TAS2R10 inhibits ChQ's reversal effect on an oxytocin-induced rise in [Ca2+]i Finally, ChQ prevents mouse PTBs induced by bacterial endotoxin LPS or progesterone receptor antagonist mifepristone more often than current commonly used tocolytics, and this prevention is largely lost in α-gustducin-knockout mice. Collectively, our results reveal that activation of the canonical TAS2R signaling system in myometrial cells produces profound relaxation of myometrium precontracted by a broad spectrum of contractile agonists, and that targeting TAS2Rs is an attractive approach to developing effective tocolytics for PTB management.-Zheng, K., Lu, P., Delpapa, E., Bellve, K., Deng, R., Condon, J. C., Fogarty, K., Lifshitz, L. M., Simas, T. A. M., Shi, F., ZhuGe, R. Bitter taste receptors as targets for tocolytics in preterm labor therapy.

Recent advances in the prevention of preterm birth

Preterm birth (PTB) remains a major obstetric healthcare problem and a significant contributor to perinatal morbidity, mortality, and long-term disability. Over the past few decades, the perinatal outcomes of preterm neonates have improved markedly through research and advances in neonatal care, whereas rates of spontaneous PTB have essentially remained static. However, research into causal pathways and new diagnostic and treatment modalities is now bearing fruit and translational initiatives are beginning to impact upon PTB rates. Successful PTB prevention requires a multifaceted approach, combining public health and educational programs, lifestyle modification, access to/optimisation of obstetric healthcare, effective prediction and diagnostic modalities, and the application of effective, targeted interventions. Progress has been made in some of these areas, although there remain areas of controversy and uncertainty. Attention is now being directed to areas where greater gains can be achieved. In this mini-review, we will briefly and selectively review a range of PTB prevention strategies and initiatives where progress has been made and where exciting opportunities await exploitation, evaluation, and implementation.