Association between body mass index and pregnancy outcome in a randomized trial of cerclage for short cervix

Differences in cervical length during the second trimester among normal weight, overweight and obese women: A systematic review and meta-analysis

Objective

Maternal obesity has been previously linked to increased risk of preterm birth; however, the actual pathophysiology behind this observation remains unknown. Cervical length seems to differentiate among overweight, obese and extremely obese patients, compared to normal weight women. However, to date the actual association between body mass index and cervical length remains unknown. In this systematic review, accumulated evidence is presented to help establish clinical implementations and research perspectives.

Methods

We searched Medline, Scopus, the Cochrane Central Register of Controlled Trials CENTRAL, Google Scholar, and Clinicaltrials.gov databases from inception till February 2023. Observational studies that reported on women undergone ultrasound assessment of their cervical length during pregnancy were included, when there was data regarding their body mass index. Statistical meta-analysis was performed with RStudio. The quality of the included studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS).

Results

Overall, 20 studies were included in this systematic review and 12 in the meta-analysis. Compared to women with normal weight, underweight women were not associated with increased risk of CL < 15 mm or < 30 mm and their mean CL was comparable (MD -1.51; 95% CI -3.07, 0.05). Overweight women were found to have greater cervical length compared to women with normal weight (MD 1.87; 95% CI 0.52, 3.23) and had a lower risk of CL < 30 mm (OR 0.65; 95% CI 0.47, 0.90).

Conclusion

Further research into whether BMI is associated with cervical length in pregnant women is deemed necessary, with large, well-designed, prospective cohort studies with matched control group.

Factors Associated with Spontaneous Preterm Birth after Ultrasound-Indicated Cerclage

Ultrasound-indicated cerclage (UIC) is recommended to prevent spontaneous preterm birth (sPTB) in women with a short cervix at mid-trimester and a history of PTB. We assessed the factors related to sPTB after UIC and determined the corresponding risks. This retrospective cohort study was conducted at a university hospital. UIC was performed between 15 and 26 weeks of gestation in women with a cervical length of <2.5 cm. Univariate and multivariate analyses were used to examine factors associated with sPTB after UIC. An earlier gestational age and shorter cervical length at UIC were associated with sPTB after UIC. While PTB history was not associated with an increased risk of sPTB, it did increase the risk of repeat cerclage after UIC. Higher levels of preoperative serum inflammatory markers and obesity significantly increased the risk of sPTB after UIC. These findings provide helpful guidance for patient counseling and management in predicting the delivery timing after UIC in women with a short cervix in the mid-trimester.

Body mass index and adverse outcomes among singletons with cerclage

OBJECTIVE

To compare the neonatal and maternal adverse outcomes among women with cerclage and prepregnancy body mass index (BMI) < versus > 30 kg/m² STUDY DESIGN: This retrospective cohort study utilized the U.S. Vital Statistics Datasets from 2011-2013. Inclusion criteria were women with non-anomalous singletons, with cerclage placement, without diabetes or hypertensive disorders, and who delivered at 20-41 weeks. The primary outcome was the composite neonatal adverse outcome (Apgar score below 5 at 5 min, birth injury, assisted ventilation for more than 6 h, neonatal seizure, or neonatal death). The secondary outcomes included the composite maternal adverse outcome (admission to intensive care unit, maternal transfusion, ruptured uterus, unplanned hysterectomy, or unplanned operating room procedure), chorioamnionitis, and cesarean delivery. Multivariable Poisson regression models with robust error variance were used, while adjusting for confounders. Adjusted relative risk with 95 % confidence intervals were calculated.

RESULTS

Of the 22,466 live births that met the inclusion criteria during the study period, 6427 (28.6 %) had cerclage and prepregnancy BMI ≥ 30 kg/m². The composite neonatal adverse outcome was significantly increased (aRR 1.45; 95 % CI 1.33-1.60) among women with cerclage and BMI ≥ 30 kg/m² when compared to those with BMI < 30 kg/m². The composite maternal adverse outcome was similar (aRR 0.93; 95 % CI 0.72-1.20) among the two groups. Chorioamnionitis (aRR 1.46; 95 % CI 1.24-1.72) and cesarean delivery (aRR 1.24; 95 % CI 1.19-1.29) were higher in women with cerclage and BMI ≥ 30 kg/m².

CONCLUSION

Among pregnancies with cerclage and delivery at 20-41 weeks, the risk of the composite neonatal adverse outcome was modestly increased in newborns delivered by women with BMI ≥ 30 kg/m² than those delivered by women with BMI < 30 kg/m². No significant difference was found in the risk of the composite maternal adverse outcome.

Pregnancy outcomes and factors affecting the clinical effects of cervical cerclage when used for different indications: A retrospective study of 326 cases

OBJECTIVE

To compare pregnancy outcomes resulting from the use of cervical cerclage for different indications and investigate factors that might influence the clinical effects of cervical cerclage.

MATERIALS AND METHODS

This was a retrospective study of pregnant women who received cervical cerclage in The Women's Hospital, Zhejiang University School of Medicine, China. Patients were divided into three groups: a history-indicated group; an ultrasound-indicated group and a physical examination-indicated group. The pregnancy outcomes of the three groups were then compared. Univariate and multivariate logistic regression analysis were performed to assess the independent risk factors.

RESULTS

Statistical differences were evident when the history-indicated group and the ultrasound-indicated group were compared with the physical examination-indicated group for gestational age at delivery [37.3(33.3-38.9), 35.4(28.9-38.4) vs. 26.1 (24.3-28.4) weeks, respectively, P < 0.05], percentage of cases delivered at < 28 weeks of gestation (13.4%, 20.3% vs. 74.3%, respectively, P < 0.05), percentage of cases delivered at < 37 weeks of gestation (42.7%, 54.2% vs. 91.4%, respectively, P < 0.05) and fetal survival rate (88.4%, 81.4% vs. 40.0%, respectively, P < 0.05). The history-indicated group and the ultrasound-indicated group were similar with regards to these outcomes. The independent risk factors affecting the clinical effects of cervical cerclage include age, body mass index (BMI), history of prior preterm birth and second-trimester loss, C-reactive protein (CRP) >5 mg/L and cervical dilation ≥3 cm (P < 0.05).

CONCLUSION

Pregnancy outcomes were similar when compared between history-indicated and ultrasound-indicated cerclage. Serial cervical surveillance is beneficial for pregnant with a history of cervical insufficiency, and the placement of cervical cerclages in response to ultrasonographically detected shortening of the cervical length is a medically acceptable alternative to the use of history-indicated cerclage.

Maternal body mass index and cervical length among women with a history of spontaneous preterm birth†

Objectives: To evaluate whether women with a prior spontaneous preterm birth (SPTB) with a higher body mass index (BMI) have a lower risk of a shortened cervix in a subsequent pregnancy.Study Design: A secondary analysis of the Maternal-Fetal Medicine Units Network RCT of omega-3 fatty acid supplementation for recurrent SPTB prevention. All women had ≥1 prior SPTB <37 weeks, a singleton pregnancy, and initiated 17-alpha hydroxyprogesterone caproate(17-OHPC). The primary exposure was pre-pregnancy BMI. The primary outcome was the shortest transvaginal cervical length <30 mm.Results: Of the 356 women with a prior SPTB receiving 17-OHPC and a cervical length available, 108 (30%) were overweight and 103 (29%) obese; 12% had a cervical length <30 mm. Fewer overweight/obese women had a shortened cervix compared to normal-weight women (43 versus 57%; odds ratio: 0.47 [95%CI: 0.25-0.89]). After adjusting for maternal age, number of prior SPTBs, and tobacco use, overweight/obese women were less than half as likely to have a shortened cervix compared to normal-weight women (adjusted odds ratio: 0.46, 95%CI: 0.24-0.89).Conclusions: Overweight and obese women with a prior SPTB receiving 17-OHPC have longer cervical lengths compared to normal weight women, and this finding could explain a possible mechanism between the decreased rate of SPTB and larger BMI.

McDonald versus Shirodkar cervical cerclage for the prevention of preterm birth: impact of body mass index

Objective: To compare obstetrical outcomes on women undergoing a McDonald or Shirodkar cerclage and to estimate the impact of maternal body mass index (BMI) on these outcomes. Methods: We conducted a retrospective review of the medical records of all women with singleton pregnancies who underwent placement of a McDonald or Shirodkar cerclage at St. Francis Hospital from January 2008 to October 2013. The subjects were categorized based on BMI groups (normal: less than 25 kg/m², overweight: 25-29 kg/m², obese: 30 kg/m² or more). The primary outcome was gestational age at delivery. Statistical analyses included chi-square, Student's t-test, and multivariable regression analysis. Results: Of 95 women, 47 (49.5%) received a Shirodkar, and 48 (50.5%) a McDonald cerclage. 16 women (16.8%) were categorized as normal weight, 35 (36.8%) as overweight, and 44 (46.3%) as obese. Gestational age at delivery differed significantly by group, decreasing with each categorical increase in BMI (normal: 39.0 ± 0.3 weeks; overweight: 36.6 ± 0.7 weeks; obese: 33.0 ± 1.1 weeks; p < .01). Overall, women receiving a Shirodkar cerclage had significantly longer pregnancies than women with a McDonald cerclage (36.7 ± 0.6 weeks versus 33.9 ± 1.0 weeks; p = .02). However, analysis showed a significant interaction between weight status and gestational age at delivery. Obese women had significantly longer pregnancies when they received a Shirodkar cerclage versus a McDonald cerclage (32.6 ± 1.0 weeks versus 28.8 ± 0.9 weeks; p < .01). However, there was no significant difference in gestational age at delivery between women categorized as normal/overweight (Shirodkar: 33.5 ± 0.9 weeks; McDonald: 32.9 ± 0.9 weeks; p = .63). Conclusions: Compared to obese women receiving a McDonald cerclage, obese women receiving a Shirodkar cerclage had significantly longer pregnancies. No significant differences in pregnancy duration were found in normal/overweight women regardless of cerclage technique. Pregnancy duration in obese women receiving a Shirodkar cerclage was similar to the pregnancy duration of normal/overweight women.

Cervical stitch (cerclage) for preventing preterm birth in singleton pregnancy

BACKGROUND

Cervical cerclage is a well-known surgical procedure carried out during pregnancy. It involves positioning of a suture (stitch) around the neck of the womb (cervix), aiming to give mechanical support to the cervix and thereby reduce risk of preterm birth. The effectiveness and safety of this procedure remains controversial. This is an update of a review last published in 2012.

OBJECTIVES

To assess whether the use of cervical stitch in singleton pregnancy at high risk of pregnancy loss based on woman's history and/or ultrasound finding of 'short cervix' and/or physical exam improves subsequent obstetric care and fetal outcome.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (30 June 2016) and reference lists of identified studies.

SELECTION CRITERIA

We included all randomised trials of cervical suturing in singleton pregnancies. Cervical stitch was carried out when the pregnancy was considered to be of sufficiently high risk due to a woman's history, a finding of short cervix on ultrasound or other indication determined by physical exam. We included any study that compared cerclage with either no treatment or any alternative intervention. We planned to include cluster-randomised studies but not cross-over trials. We excluded quasi-randomised studies. We included studies reported in abstract form only.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion. Two review authors independently assessed risk of bias and extracted data. We resolved discrepancies by discussion. Data were checked for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

This updated review includes a total of 15 trials (3490 women); three trials were added for this update (152 women). Cerclage versus no cerclageOverall, cerclage probably leads to a reduced risk of perinatal death when compared with no cerclage, although the confidence interval (CI) crosses the line of no effect (RR 0.82, 95% CI 0.65 to 1.04; 10 studies, 2927 women; moderate quality evidence). Considering stillbirths and neonatal deaths separately reduced the numbers of events and sample size. Although the relative effect of cerclage is similar, estimates were less reliable with fewer data and assessed as of low quality (stillbirths RR 0.89, 95% CI 0.45 to 1.75; 5 studies, 1803 women; low quality evidence; neonatal deaths before discharge RR 0.85, 95% CI 0.53 to 1.39; 6 studies, 1714 women; low quality evidence). Serious neonatal morbidity was similar with and without cerclage (RR 0.80, 95% CI 0.55 to 1.18; 6 studies, 883 women; low-quality evidence). Pregnant women with and without cerclage were equally likely to have a baby discharged home healthy (RR 1.02, 95% CI 0.97 to 1.06; 4 studies, 657 women; moderate quality evidence).Pregnant women with cerclage were less likely to have preterm births compared to controls before 37, 34 (average RR 0.77, 95% CI 0.66 to 0.89; 9 studies, 2415 women; high quality evidence) and 28 completed weeks of gestation.Five subgroups based on clinical indication provided data for analysis (history-indicated; short cervix based on one-off ultrasound in high risk women; short cervix found by serial scans in high risk women; physical exam-indicated; and short cervix found on scan in low risk or mixed populations). There were too few trials in these clinical subgroups to make meaningful conclusions and no evidence of differential effects. Cerclage versus progesteroneTwo trials (129 women) compared cerclage to prevention with vaginal progesterone in high risk women with short cervix on ultrasound; these trials were too small to detect reliable, clinically important differences for any review outcome. One included trial compared cerclage with intramuscular progesterone (75 women) which lacked power to detect group differences. History indicated cerclage versus ultrasound indicated cerclageEvidence from two trials (344 women) was too limited to establish differences for clinically important outcomes.

AUTHORS' CONCLUSIONS

Cervical cerclage reduces the risk of preterm birth in women at high-risk of preterm birth and probably reduces risk of perinatal deaths. There was no evidence of any differential effect of cerclage based on previous obstetric history or short cervix indications, but data were limited for all clinical groups. The question of whether cerclage is more or less effective than other preventative treatments, particularly vaginal progesterone, remains unanswered.

Vaginal Cerclage: Preoperative, Intraoperative, and Postoperative Management

The role of the cerclage procedure has expanded from its initial application as treatment or prevention of cervical insufficiency to prevention of recurrent spontaneous preterm birth. Although recent prospective studies have clarified the indications for cerclage, additional prospective studies are needed to help define optimal perioperative management. Herein, we review the current data to provide the clinician with the most evidence-based approach to managing patients who require cerclage.

Co-morbidity of cervical incompetence with polycystic ovarian syndrome (PCOS) negatively impacts prognosis: A retrospective analysis of 178 patients

Background

Cervical incompetence is an important cause of miscarriage and premature birth and polycystic ovary syndrome is a heterogeneous endocrine disorder that is the most common cause of anovulatory infertility and eugonadotrophic hypogonadism. By now, it is still debated whether women with PCOS have an increased risk of miscarriage and there have been no studies about the pregnancy outcomes of cervical incompetence patients with PCOS.

Methods

The following clinical data of cervical incompetence patients with/without PCOS who were treated between September 2006 and September 2013 were retrospectively analysed: onset gestational age, termination gestational age, pregnancy outcome, co-morbid insulin resistance (IR) in PCOS patients, the influence of IR, co-morbid hyperandrogenism (HA) in PCOS patients, and the influence of HA. The independent samples t-test and chi-square trend test were used to analyse the data.

Results

A total of 178 singleton pregnancy cases with cervical incompetence were identified. The average onset gestational age was 23.9 ± 4.3 weeks, and the average termination gestational age was 32.5 ± 5.5 weeks. Of these 178 singleton pregnancy cases, 40 (22.5 %) ended in miscarriage, 82 (46.1 %) ended in preterm birth, and 56 (31.5 %) ended in term birth. Eighty cases (44.9 %) exhibited PCOS co-morbidity, and those cases had an average onset gestational age of 22.3 ± 3.8 weeks and an average termination gestational age of 31.2 ± 5.7 weeks, which were both significantly different from those of the non-PCOS group (both P < 0.001). Compared with the non-PCOS group (15.3 % miscarriage, 48.0 % preterm birth, and 36.7 % term birth), the PCOS group exhibited worse pregnancy outcomes (31.3 % miscarriage, 43.8 % preterm birth, and 25 % term birth) (P = 0.01). Among the 80 PCOS patients, 45 (56.3 %) exhibited co-morbid IR, and the IR group exhibited significantly worse pregnancy outcomes than the non-IR group (P = 0.03). Among the 80 PCOS patients, 54 cases (67.5 %) exhibited co-morbid HA, and there was no statistical difference on the pregnancy outcomes between the two groups. The multivariate logistic regression model revealed that PCOS was significantly correlated with miscarriage (OR: 3.72, 95 % CI: 1.37–10.13).

Conclusions

The cervical incompetence patients with co-morbid PCOS exhibited earlier onset gestational ages, earlier termination gestational ages and worse pregnancy outcomes. For patients with co-morbid insulin resistance, the pregnancy outcomes were worse than expected.

The impact of obesity on cervical cerclage efficacy: A systematic review of the literature

BACKGROUND

Cervical cerclage is a commonly applied procedure which is used as a preventive measure against preterm births among women with a short cervix (<25mm) or with previous painless mid-trimester pregnancy losses. The purpose of the present study is to evaluate whether the presence of maternal obesity reduces the efficacy of cervical cerclage.

MATERIALS AND METHODS

We searched Medline (1966-2015), Scopus (2004-2015), Popline (1974-2015) and ClinicalTrials.gov (2008-2015) along with reference lists of electronically retrieved studies.

RESULTS

Three studies were included in our review which involved 606 women. Among them 210 were obese (BMI>30 kg/m2) and 47 morbidly obese (BMI >40 kg/m2). The presence of obesity among women who had a cervical cerclage due to ultrasound or history indications did not seem to affect the gestational age at delivery or the neonatal birthweight. Furthermore, according to the findings of a single study it did not seem to reduce the gestational latency period in days (normal weight group 24.3±3.2, overweight group 21.1±5.1, obese group 21.4±4.9 p = 0.171).

CONCLUSION

According to the findings of our systematic review obesity does not influence the efficacy of cervical cerclage. However, firm results are precluded due to the small number and the methodological heterogeneity of existing studies. Further, studies are needed to corroborate our findings.

[Epidemiology of loss pregnancy]

OBJECTIVES

Study of epidemiology of pregnancy loss.

MATERIALS AND METHOD

A systematic review of the literature was performed using Pubmed and the Cochrane library databases and the guidelines from main international societies.

RESULTS

The occurrence of first trimester miscarriage is 12% of pregnancies and 25% of women. Miscarriage risk factors are ages of woman and man, body mass index greater than or equal to 25kg/m(2), excessive coffee drinking, smoking and alcohol consumption, exposure to magnetic fields and ionizing radiation, history of abortion, some fertility disorders and impaired ovarian reserve. Late miscarriage (LM) complicates less than 1% of pregnancies. Identified risk factors are maternal age, low level of education, living alone, history of previous miscarriage, of premature delivery and of previous termination of pregnancy, any uterine malformation, trachelectomy, existing bacterial vaginosis, amniocentesis, a shortened cervix and a dilated cervical os with prolapsed membranes. Fetal death in utero has a prevalence of 2% in the world and 5/1000 in France. Its main risk factors are detailed in the chapter.

Selected vaginal bacteria and risk of preterm birth: an ecological perspective

We examined the community ecology of vaginal microbial samples taken from pregnant women with previous preterm birth experience to investigate whether targeted pathogenic and commensal bacteria are related to risk of preterm birth in the current pregnancy. We found a significant correlation between the community structure of selected bacteria and birth outcome, but the correlation differed among self-reported racial/ethnic groups. Using a community ordination analysis, we observed infrequent co-occurrence of Mycoplasma and bacteria vaginosis associated bacteria 3 (BVAB3) among black and Hispanic participants. In addition, we found that the vaginal bacteria responded differently in different racial/ethnic groups to modifications of maternal behavioral (ie, douching and smoking) and biological traits (ie, body mass index [BMI]). Even after accounting for these maternal behaviors and traits, the selected vaginal bacteria was significantly associated with preterm birth among black and Hispanic participants. By contrast, white participants did not exhibit significant correlation between microbial community and birth outcome. Findings from this study affirm the necessity of considering women's race/ethnicity when evaluating the correlation between vaginal bacteria and preterm birth. The study also illustrates the importance of studying the vaginal microbiota from an ecological perspective, and demonstrates the power of ecological community analysis to improve understanding of infectious disease.