Prediction and prevention of spontaneous preterm birth in twin gestations

Greater risk of type 2 diabetes progression in multifetal gestations with gestational diabetes: the impact of obesity

BACKGROUND

The relationship between gestational diabetes mellitus and adverse outcomes in multifetal pregnancies is complex and controversial. Moreover, limited research has focused on the risk of gestational diabetes mellitus progression to type 2 diabetes mellitus specifically in multifetal pregnancies, resulting in conflicting results from existing studies.

OBJECTIVE

This study aimed to assess the risk of gestational diabetes mellitus progression to type 2 diabetes mellitus between singleton and multifetal pregnancies in a large cohort of parturients with a 5-year follow-up.

STUDY DESIGN

A retrospective study was conducted on a prospective cohort of pregnant individuals with pregnancies between January 1, 2017, and December 31, 2020, followed up to 5 years after delivery. Glucose levels during pregnancy were obtained from the Meuhedet Health Maintenance Organization laboratory system and cross-linked with the Israeli National Diabetes Registry. The cohort was divided into 4 groups: singleton pregnancy without gestational diabetes mellitus, singleton pregnancy with gestational diabetes mellitus, multifetal pregnancy without gestational diabetes mellitus, and multifetal pregnancy with gestational diabetes mellitus. Gestational diabetes mellitus was defined according to the American Diabetes Association criteria using the 2-step strategy. Univariate analyses, followed by survival analysis that included Kaplan-Meier hazard curves and Cox proportional-hazards models, were used to assess differences between groups and calculate the adjusted hazard ratios with 95% confidence intervals for progression to type 2 diabetes mellitus.

RESULTS

Among 88,611 parturients, 61,891 cases met the inclusion criteria. The prevalence of type 2 diabetes mellitus was 6.5% in the singleton pregnancy with gestational diabetes mellitus group and 9.4% in the multifetal pregnancy with gestational diabetes mellitus group. Parturients with gestational diabetes mellitus, regardless of plurality, were older and had higher fasting plasma glucose levels in the first trimester of pregnancy. The rates of increased body mass index, hypertension, and earlier gestational age at delivery were significantly higher in the gestational diabetes mellitus group among patients with singleton pregnancies but not among patients with multifetal pregnancies. Survival analysis demonstrated that gestational diabetes mellitus was associated with adjusted hazard ratios of type 2 diabetes mellitus of 4.62 (95% confidence interval, 3.69-5.78) in singleton pregnancies and 9.26 (95% confidence interval, 2.67-32.01) in multifetal pregnancies (P<.001 for both). Stratified analysis based on obesity status revealed that, in parturients without obesity, gestational diabetes mellitus in singleton pregnancies increased the risk of type 2 diabetes mellitus by 10.24 (95% confidence interval, 6.79-15.44; P<.001) compared with a nonsignificant risk in multifetal pregnancies (adjusted hazard ratio, 9.15; 95% confidence interval, 0.92-90.22; P=.059). Among parturients with obesity, gestational diabetes mellitus was associated with an increased risk of type 2 diabetes mellitus for both singleton and multifetal pregnancies (adjusted hazard ratio, 3.66; [95% confidence interval, 2.81-4.67; P<.001] and 9.31 [95% confidence interval, 2.12-40.76; P=.003], respectively).

CONCLUSION

Compared with gestational diabetes mellitus in singleton pregnancies, gestational diabetes mellitus in multifetal pregnancies doubles the risk of progression to type 2 diabetes mellitus. This effect is primarily observed in patients with obesity. Our findings underscore the importance of providing special attention and postpartum follow-up for patients with multifetal pregnancies and gestational diabetes mellitus, especially those with obesity, to enable early diagnosis and intervention for type 2 diabetes mellitus.

Serum hsCRP in early pregnancy and preterm delivery in twin gestations: a prospective cohort study

BACKGROUND

Systemic inflammation during pregnancy may be associated with preterm delivery (PTD), but data for twin gestations are lacking. The aim of this study was to examine the association of serum high-sensitivity C-reactive protein (hsCRP), a marker of inflammation, in early pregnancy of twin gestations with risk of PTD, including spontaneous (sPTD) and medical-induced preterm delivery (mPTD).

METHODS

A prospective cohort study involved 618 twin gestations was conducted in a tertiary hospital in Beijing, from 2017 to 2020. Serum samples collected in early pregnancy were analyzed for hsCRP using particle-enhanced immunoturbidimetric method. Unadjusted and adjusted geometric means (GM) of hsCRP were estimated using linear regression, and compared between PTD before 37 weeks of gestation and term delivery at 37 or more weeks of gestation using Mann-Whitney rank sum test. The association between hsCRP tertiles and PTDs was estimated using logistic regression, and further converted overestimated odds ratios into relative risks (RR).

RESULTS

A total of 302 (48.87%) women were classified as PTD, with 166 sPTD and 136 mPTD. The adjusted GM of serum hsCRP was higher in PTDs (2.13 mg/L, 95% confidence interval [CI] 2.09 -2.16) compared to term deliveries (1.84 mg/L, 95% CI 1.80 -1.88) (P < 0.001). Compared with the lowest tertile of hsCRP, the highest tertile was associated with increased risk of PTD (adjusted relative risks [ARR] 1.42; 95% CI: 1.08-1.78). Among twin pregnancies, the adjusted association between high values of serum hsCRP in early pregnancy and preterm delivery was only observed in the subgroup of spontaneous preterm deliveries (ARR 1.49, 95%CI:1.08-1.93).

CONCLUSIONS

Elevated hsCRP in early pregnancy was associated with increased risk of PTD, particular the risk of sPTD in twin gestations.

Gestational diabetes and fetal growth in twin compared with singleton pregnancies

BACKGROUND

Gestational diabetes mellitus is associated with accelerated fetal growth in singleton pregnancies but may affect twin pregnancies differently because of the slower growth of twin fetuses during the third trimester of pregnancy and their greater predisposition to fetal growth restriction.

OBJECTIVE

This study aimed to evaluate the association of gestational diabetes mellitus with longitudinal fetal growth in twin pregnancies and to compare this association with that observed in singleton pregnancies.

STUDY DESIGN

This was a retrospective cohort study of all women with a singleton or twin pregnancy who were followed up at a single tertiary referral center between January 2011 and April 2020. Data on estimated fetal weight and individual fetal biometric indices were extracted from ultrasound examinations of eligible women. Generalized linear models were used to model and compare the change in fetal weight and individual biometric indices as a function of gestational age between women with and without gestational diabetes mellitus in twin pregnancies and between women with and without gestational diabetes mellitus in singleton pregnancies. The primary outcome was estimated fetal weight as a function of gestational age. The secondary outcomes were longitudinal growth of individual fetal biometric indices and the rate of small for gestational age and large for gestational age at birth.

RESULTS

A total of 26,651 women (94,437 ultrasound examinations) were included in the analysis: 1881 with a twin pregnancy and 24,770 with a singleton pregnancy. The rate of gestational diabetes mellitus in the twin and singleton groups was 9.6% (n=180) and 7.6% (n=1893), respectively. The estimated fetal weight in singleton pregnancies with gestational diabetes mellitus was significantly higher than that in pregnancies without gestational diabetes mellitus (P<.001) starting at approximately 30 weeks of gestation. The differences remained similar after adjusting for maternal age, chronic hypertension, nulliparity, and neonatal sex (P<.001). In twin pregnancies, fetal growth was similar between pregnancies with and without gestational diabetes mellitus (P=.105 and P=.483 for unadjusted and adjusted models, respectively). The findings were similar to the association of gestational diabetes mellitus with the risk of large for gestational fetuses and the growth of each biometric index. When stratified by type of gestational diabetes mellitus treatment, twin pregnancies with gestational diabetes mellitus was associated with accelerated fetal growth only in the subgroup of women with medically treated gestational diabetes mellitus (P<.001), which represented 12% (n=21) of the twin pregnancy group with gestational diabetes mellitus.

CONCLUSION

In contrast to singleton pregnancies, twin pregnancies with gestational diabetes mellitus is less likely to be associated with accelerated fetal growth. This finding has raised the question of whether the diagnostic criteria for gestational diabetes mellitus and the blood glucose targets in women diagnosed with gestational diabetes mellitus should be individualized for twin pregnancies.

Elective fetal reduction by radiofrequency ablation in monochorionic diamniotic twins decreases adverse outcomes compared to ongoing monochorionic diamniotic twins

BACKGROUND

Multifetal pregnancy reduction is a technique used to reduce the fetal number to mitigate the risks of adverse outcomes associated with multiple gestations. Monochorionic diamniotic twin pregnancies are subject to unique complications, contributing to adverse pregnancy outcomes. Thus, patients have an option to electively reduce 1 fetus to improve outcomes.

OBJECTIVE

This study aimed to compare outcomes of elective reduction of monochorionic diamniotic twins by radiofrequency ablation to planned ongoing monochorionic diamniotic twins.

STUDY DESIGN

We performed a retrospective review of 315 monochorionic diamniotic twin gestations that underwent first-trimester ultrasound within 1 institution. Planned electively reduced twins were compared with ongoing monochorionic diamniotic twins. All reductions were performed via radiofrequency ablation of the cord insertion site into the fetal abdomen. The primary outcome was preterm birth at <36 weeks' gestation. Secondary outcomes included gestational age at delivery; preterm birth at less than 37-, 34-, 32-, and 28-weeks' gestation; unintended loss; and adverse perinatal outcomes.

RESULTS

Among 315 monochorionic diamniotic pregnancies, 14 (4.4%) underwent elective multifetal pregnancy reduction, and 301 (95.6%) were planned ongoing twins. The mean gestational age of radiofrequency ablation in the elective multifetal pregnancy reduction group was 15.1±0.68 weeks. Patients who underwent elective multifetal pregnancy reduction had significantly higher maternal age (P<.01) and were more likely to be Asian (P<.01). Moreover, they were more likely to have undergone in vitro fertilization (P=.03) and chorionic villus sampling (P<.01). There was a significantly higher rate of term deliveries in the elective radiofrequency ablation group compared with ongoing twins (gestational age, 38 weeks [interquartile range, 36.1-39.1] vs 35.9 weeks [interquartile range, 34.0-36.9]; P<.01). Patients with ongoing pregnancies had a trend of increased rate of preterm birth at <36 weeks' gestation (odds ratio, 3.4; 95% confidence interval, 1.0-12.0; P=.06), a significantly increased risk of preterm birth at <37 weeks' gestation (odds ratio, 8.0; 95% confidence interval, 2.4-26.4; P<.01), and no difference at less than 34-, 32-, or 28- weeks' gestation. All patients who underwent elective radiofrequency ablation had successful pregnancies with no pregnancy losses or terminations. Of ongoing gestations, 36 required procedures, including 16 (5.3%) medically indicated radiofrequency ablation, 14 (4.6%) laser ablation, and 6 (1.9%) amnioreductions. Furthermore, 22 patients (7.3%) with planned ongoing twins had total pregnancy loss at <24 weeks' gestation. Notably, 12 patients (4.0%) had unintended loss of 1 fetus before 24 weeks' gestation in the ongoing pregnancy cohort, and 12 patients (4.0%) had unintended loss of both fetuses before 24 weeks' gestation. Moreover, 5 patients (1.7%) in the ongoing pregnancy group had intrauterine fetal demise at >24 weeks' gestation and 10 patients (3.3%) electively terminated both fetuses. There was no significant difference in loss rates between the 2 groups.

CONCLUSION

In this study of monochorionic diamniotic twins, patients who elected to undergo multifetal pregnancy reduction had significantly lower rates of preterm birth at <37 weeks and a lower trend of preterm birth at <36 weeks' gestation without an increased risk of pregnancy loss. Median gestational age at delivery was significantly higher in the elective multifetal pregnancy reduction group (38 weeks) than in the ongoing pregnancy group (35.9 weeks). Further research is needed to clarify if multifetal pregnancy reduction improves long-term outcomes.

The Predictive Value of the Cervical Consistency Index to Predict Spontaneous Preterm Birth in Asymptomatic Twin Pregnancies at the Second-Trimester Ultrasound Scan: A Prospective Cohort Study

Novel transvaginal ultrasound (TVU) markers have been proposed to improve spontaneous preterm birth (sPTB) prediction. Preliminary results of the cervical consistency index (CCI), uterocervical angle (UCA), and cervical texture (CTx) have been promising in singletons. However, in twin pregnancies, the results have been inconsistent. In this prospective cohort study of asymptomatic twin pregnancies assessed between 18⁺⁰–22⁺⁰ weeks, we evaluated TVU derived cervical length (CL), CCI, UCA, and the CTx to predict sPTB < 34⁺⁰ weeks. All iatrogenic PTB were excluded. In the final cohort of 63 pregnancies, the sPTB rate < 34⁺⁰ was 16.3%. The CCI, UCA, and CTx, including the CL was significantly different in the sPTB < 34⁺⁰ weeks group. The best area under the receiver operating characteristic curve (AUC) for sPTB < 34⁺⁰ weeks was achieved by the CCI 0.82 (95%CI, 0.72–0.93), followed by the UCA with AUC 0.72 (95%CI, 0.57–0.87). A logistic regression model incorporating parity, chorionicity, CCI, and UCA resulted in an AUC of 0.91 with a sensitivity of 55.3% and specificity of 88.1% for predicting sPTB < 34⁺⁰. The CCI performed better than other TVU markers to predict sPTB < 34⁺⁰ in twin gestations, and the best diagnostic accuracy was achieved by a combination of parity, chorionicity, CCI, and UCA.

Quantitative fetal fibronectin for prediction of preterm birth in asymptomatic twin pregnancy

INTRODUCTION

To evaluate cervicovaginal fluid quantitative fetal fibronectin, measured by a bedside analyzer, to predict spontaneous preterm birth in twin pregnancy before 30 weeks of gestation.

MATERIAL AND METHODS

In a prospective cohort study, we studied the accuracy of quantitative fetal fibronectin measured between 18 and 27⁺⁶ weeks of gestation in high-risk asymptomatic women with twin pregnancies, to predict spontaneous preterm birth before 30 weeks of gestation. Predefined fetal fibronectin thresholds were ≥10, ≥50 and ≥200 ng/mL. Predictive statistics were also calculated to evaluate accuracy of "early" tests, performed between 18 and 21⁺⁶ weeks and "standard" tests performed between 22⁺⁰ and 27⁺⁶ weeks of gestation in the same cohort. Subgroup analysis was performed according to cervical length measurement. In addition, we compared accuracy of prediction with quantitative fetal fibronectin measured during the standard test period in asymptomatic twin pregnancy with no additional risk factors, to twin pregnancies with one or more additional risk factors for spontaneous preterm birth.

RESULTS

Of 130 eligible women identified with quantitative fetal fibronectin tests undertaken during the standard testing period, 9% delivered before 30 weeks of gestation. Quantitative fetal fibronectin was significantly related to outcome before 30/40 (ROC curves of 0.8 [95% CI 0.7-1]). Early tests were not significantly predictive; ROC area 0.53 (95% CI 0.29-0.81). There was a trend towards better predictive accuracy when one or more additional risk factors for spontaneous preterm birth or cervical length were considered.

CONCLUSIONS

Quantitative fetal fibronectin measured from 22 to 27⁺⁶ weeks of gestation accurately predicts spontaneous preterm birth at <30 weeks of gestation. Tests undertaken earlier are of limited value. Consideration of cervical length or prior history in addition to quantitative fetal fibronectin strengthens prediction.

Comparing pregnancy outcomes and loss rates in elective twin pregnancy reduction with ongoing twin gestations in a large contemporary cohort

BACKGROUND

As compared with singleton gestations, twin pregnancies are associated with a significantly higher risk of preterm birth and maternal complications as well as fetal and neonatal morbidity and mortality. Multifetal pregnancy reduction is a technique developed in the 1980s to reduce the fetal number in higher-order multiple pregnancies to reduce the risk of adverse pregnancy outcomes, most importantly preterm birth.

OBJECTIVE

The objective of the study was to compare pregnancy outcomes and loss rates in elective twin pregnancy reduction to ongoing twin gestations in a large contemporary cohort.

STUDY DESIGN

This was a retrospective review of dichorionic diamniotic twin gestations that underwent first-trimester ultrasound at our institution from January 2008 to September 2016. Planned elective 2-to-1 multifetal pregnancy reductions at less than 15 weeks' gestation were compared with ongoing dichorionic diamniotic twin gestations. Data were collected via chart review. Demographics between 2-to-1 reduced singletons and ongoing twins were assessed using a Student t test or a Wilcoxon rank-sum test, as appropriate, for continuous variables and χ² or Fisher exact tests, as appropriate, for categorical variables. Univariable and multivariable logistic regressions were used to compare pregnancy outcomes between ongoing twins and reduced singletons adjusting for maternal age, body mass index, race, in vitro fertilization, use of chorionic villus sampling, prior term birth, and prior preterm birth.

RESULTS

Of 1070 dichorionic diamniotic twin pregnancies identified, completed follow-up data were available and analyzed for 855 patients (79.9%). Among those, 250 (29.2%) were 2-to-1 singletons and 605 (70.8%) were ongoing twins. Reduced singleton patients were slightly older, more likely white, and had lower body mass index. They were also more likely to have undergone in vitro fertilization (63.6% vs 48.8%), had chorionic villus sampling (92% vs 37.5%), and had prior term births (54% vs 35.7%). Compared with 2-to-1 singletons, the adjusted odds of having preterm delivery at 37 weeks for ongoing twins were 5.62 times (95% confidence interval, 3.67-8.61; P < .001) and 2.22 times (95% confidence interval, 1.20-4.11; P < .001) at 34 weeks. While intrauterine growth restriction, placental abruption, and gestational diabetes were not significant, ongoing twins were more likely to have a cesarean delivery (odds ratio, 5.53, 95% confidence interval, 3.60-8.49; P < .001) and preeclampsia (odds ratio, 3.33, 95% confidence interval, 1.60-6.96; P < .001) after adjusting for maternal characteristics. There were also significant differences between groups for preterm premature rupture of membranes and low birthweight at less than the fifth and 10th percentiles. Total pregnancy loss (at 24 and 20 weeks) was similar between singleton and ongoing twins (4% vs 2.5%, P = .23, and 3.6% vs 1.7%, P = .09 for respective weeks). There were no significant differences in the rate of unintended pregnancy loss (2.4% vs 2.3%; P = .94) and the rate of intrauterine fetal death greater than 24 weeks (1.2% vs 0.7%; P = .43) in reduced singleton versus ongoing twin group, respectively.

CONCLUSION

In our study, patients who elected to reduce to a singleton pregnancy had a higher gestational age of delivery and lower rates of preterm birth and pregnancy complications without an increased risk of pregnancy loss.

The fetal fibronectin test: 25 years after its development, what is the evidence regarding its clinical utility? A systematic review and meta-analysis

Background: The identification of women at risk for preterm birth should allow interventions which could improve neonatal outcome. Fetal fibronectin, a glycoprotein which acts normally as glue between decidua and amniotic membranes could be a good marker of impending labour when its concentration in cervicovaginal secretions between 22 and 36 weeks of gestation is ≥50 ng/mL. Many authors worldwide have tested this marker with many different methodologies and clinical settings, but conclusions about its clinical use are mixed. It is time for a comprehensive update through a systematic review and meta-analysis.Methods: We searched PubMed, Cochrane Library, and Embase, supplemented by manual search of bibliographies of known primary and review articles, international conference papers, and contact with experts from 1-1990 to 2-2018. We have selected all type of studies involving fetal fibronectin test accuracy for preterm delivery. Two authors independently extracted data about study characteristics and quality from identified publications. Contingency tables were constructed. Reference standards were preterm delivery before 37, 36, 35, 34, and 32 weeks, within 28, 21, 14, or 7 d and within 48 h. Data were pooled to produce summary likelihood ratios for positive and negative tests results.Results: One hundred and ninety-three primary studies were identified allowing analysis of 53 subgroups. In all settings, none of the summary likelihood ratios were >10 or <0.1, thus indicating moderate prediction, particularly in asymptomatic women and in multiple gestations.Conclusions: The fetal fibronectin test should not be used as a screening test for asymptomatic women. For high-risk asymptomatic women, and especially for women with multiple pregnancies, the performance of the fetal fibronectin test was also too low to be clinically relevant. Consensual use as a diagnostic tool for women with suspected preterm labor, the best use policy probably still depends on local contingencies, future cost-effectiveness analysis, and comparison with other more recent available biochemical markers.

Bed rest with and without hospitalisation in multiple pregnancy for improving perinatal outcomes

BACKGROUND

Strict or partial bed rest in hospital or at home is commonly recommended for women with multiple pregnancy to improve pregnancy outcomes. In order to advise women to rest in bed for any length of time, a policy for clinical practice needs to be supported by reliable evidence and weighed against possible adverse effects resulting from prolonged activity restriction.

OBJECTIVES

The objective of this review is to assess the effectiveness of bed rest in hospital or at home to improve perinatal outcomes in women with a multiple pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 May 2016), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 May 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We selected all individual and cluster-randomised controlled trials evaluating the effect of strict or partial bed rest at home or in hospital compared with no activity restriction during multiple pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and methodological quality. We evaluated the quality of the evidence using the GRADE approach and summarised it in 'Summary of findings' tables.

MAIN RESULTS

We included six trials, involving a total of 636 women with a twin or triplet pregnancy (total of 1298 babies). We assessed all of the included trials as having a low risk of bias for random sequence generation. Apart from one trial with an unclear risk of bias, we judged all remaining trials to be of low risk of bias for allocation concealment.Five trials (495 women and 1016 babies) compared strict bed rest in hospital with no activity restriction at home. There was no difference in the risk of very preterm birth (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.66 to 1.58, five trials, 495 women, assuming complete correlation between twins/triplets, low-quality evidence), perinatal mortality (RR 0.65, 95% CI 0.35 to 1.21, five trials, 1016 neonates, assuming independence between twins/triplets, low-quality evidence) and low birthweight (RR 0.95, 95% CI 0.75 to 1.21, three trials, 502 neonates, assuming independence between twins/triplets, low-quality evidence). We observed no differences for the risk of small-for-gestational age (SGA) (RR 0.75, 95% CI 0.56 to 1.01, two trials, 293 women, assuming independence between twins/triplets, low-quality evidence) and prelabour preterm rupture of the membrane (PPROM) (RR 1.30, 95% CI 0.71 to 2.38, three trials, 276 women, low-quality evidence). However, strict bed rest in hospital was associated with increased spontaneous onset of labour (RR 1.05, 95% CI 1.02 to 1.09, P = 0.004, four trials, 488 women) and a higher mean birthweight (mean difference (MD) 136.99 g, 95% CI 39.92 to 234.06, P = 0.006, three trials, 314 women) compared with no activity restriction at home.Only one trial (141 women and 282 babies) compared partial bed rest in hospital with no activity restriction at home. There was no evidence of a difference in the incidence of very preterm birth (RR 2.30, 95% CI 0.84 to 6.27, 141 women, assuming complete correlation between twins, low-quality evidence) and perinatal mortality (RR 4.17, 95% CI 0.90 to 19.31, 282 neonates, assuming complete independence twins, low-quality evidence) between the intervention and control group. Low birthweight was not reported in this trial. We found no differences in the risk of PPROM and SGA between women receiving partial bed rest and the control group (low-quality evidence). Women on partial bed rest in hospital were less likely to develop gestational hypertension compared with women without activity restriction at home (RR 0.30, 95% CI 0.16 to 0.59, P = 0.0004, 141 women).Strict or partial bed rest in hospital was found to have no impact on other secondary outcomes. None of the trials reported on costs of the intervention or adverse effects such as the development of venous thromboembolism or psychosocial effects.

AUTHORS' CONCLUSIONS

The evidence to date is insufficient to inform a policy of routine bed rest in hospital or at home for women with a multiple pregnancy. There is a need for large-scale, multicenter randomised controlled trials to evaluate the benefits, adverse effects and costs of bed rest before definitive conclusions can be drawn.

Do serial measurements of cervical length improve the prediction of preterm birth in asymptomatic women with twin gestations?

BACKGROUND

Cervical length at midtrimester is a powerful predictor of preterm birth in twin gestations. However, given the fact that, in some cases, cervical shortening may become evident only later during the second trimester, it seems reasonable that serial monitoring of cervical length may improve the detection of preterm birth in women with twins. However, data in support of such a practice are limited and conflicting. The contradictory results may be related to the fact that in most of these studies, the analysis of the predictive value of serial measurements of cervical length was limited to data derived from only two sequential measurements of cervical length, while data on the predictive value of multiple (>2) measurements are scarce.

OBJECTIVE

We sought to determine whether serial measurements of cervical length can improve the prediction of preterm birth in asymptomatic women with twin gestations compared with a single measurement of cervical length at midgestation.

STUDY DESIGN

This was a retrospective cohort study of women with twin pregnancies followed up in a tertiary medical center from 2012 through 2014. All participants underwent routine measurement of cervical length at midgestation and every 2-3 weeks thereafter until 28-32 weeks. For each patient, cervical length was determined at the following time periods: 18+0 to 21+6 weeks (period 1, routine exam), 22+0 to 24+6 weeks (period 2), 25+0 to 27+6 weeks (period 3), and 28+0 to 32+0 weeks (period 4). Measurements of cervical length at periods 2-4 were analyzed in the form of either absolute length (in millimeters) or percent shortening relative to cervical length at period 1. The performance of a stepwise algorithm that incorporated serial measurements of cervical length for the prediction of preterm birth was compared to that achieved with a single measurement of cervical length at period 1.

RESULTS

Overall, 441 women with twin pregnancies who were eligible for the study underwent a total of 2374 cervical length measurements. The association of a short cervix (<10th percentile) with preterm birth at <32 weeks persisted in each of the 4 periods of gestation [odds ratio (95% confidence interval): 7.2 (3.1-16.5), 15.3 (6.4-36.7), 10.3 (4.4-24.3), and 23.1(8.3-64.1), respectively]. Compared with a single measurement of cervical length at midgestation (period 1), a stepwise algorithm integrating serial cervical length measurements from all 4 successive gestational age periods resulted in a significant increase in the area under the receiver operating characteristic curve (0.917 vs 0.613, P < .001). Similarly, when a target false-positive rate of 5% was used, the same stepwise algorithm was associated with a higher detection rate (69% vs 28%, P < .001), higher positive likelihood ratio (14.54 vs 5.12), and lower negative likelihood ratio (0.32 vs 0.76) for preterm birth at <32 weeks compared with a single measurement of cervical length at period 1.

CONCLUSION

Integration of serial measurements of cervical length using a stepwise algorithm in asymptomatic women with twin gestations can improve the detection of women at risk of preterm birth. Prospective studies are needed to validate these findings, and to investigate whether improved risk assessment performance is sufficient to offset the additional costs associated with serial cervical length measurements.

Serial cervical length determination in twin pregnancies reveals 4 distinct patterns with prognostic significance for preterm birth

BACKGROUND

Women with a twin gestation are at increased risk for preterm birth (PTB), and sonographic cervical length (CL) is a powerful predictor for spontaneous PTB. Obstetricians frequently monitor CL in multiple gestations; yet, the optimal method to integrate and interpret the results of serial sonographic CL has not been determined.

OBJECTIVE

We sought to determine whether there are different patterns of cervical shortening in twin gestations, and whether such patterns are related to the risk of PTB.

STUDY DESIGN

We conducted a retrospective study of all women with twins followed up in a single tertiary referral center during 2012 through 2014. All women underwent serial measurements of CL every 2-3 weeks starting from 14-18 weeks and until 28-32 weeks of gestation. Changes in CL were analyzed and classified into distinct patterns that were initially identified by visual inspection of all individual cases. Each pattern was then characterized by several parameters including information about when cervical shortening began, the rate of shortening, and whether a plateau was observed. Locally weighted regression mean profiles were generated to describe each pattern of CL over time. The association of these patterns with spontaneous PTB was determined. The specific characteristics of each pattern that further determined the risk of PTB were identified using multivariable logistic regression analysis.

RESULTS

We studied 441 women who had a total of 2826 measurements of CL done. Overall, 4 main patterns of change in CL were identified: pattern I, stable cervix (n = 196); pattern II, early and rapid shortening (n = 18); pattern III, late shortening (n = 109); and pattern IV, early shortening with a plateau (n = 118). The rate of PTB at <34 weeks was lowest in cases of pattern I (11.7%), followed by pattern IV (14.4%) and pattern III (20.2%), and was highest for women with pattern II (44.4%) (P < .001). In cases with pattern III (late shortening), the most important factors affecting the risk of PTB were the shortening rate, the gestational age at the onset of cervical shortening, and the initial plateau of CL. In the case of pattern IV (early shortening with a plateau), it was only the new plateau at which cervical shortening stopped that was associated with the risk of PTB.

CONCLUSION

Changes in sonographic CL over time in twin gestations can be classified into 4 patterns, each associated with a different risk of PTB.

Does gestational diabetes affect fetal growth and pregnancy outcome in twin pregnancies?

BACKGROUND

Women with twin pregnancies are at increased risk for fetal growth restriction, which might be attributed to the limited maternal resources that are being shared by >1 fetus. Based on that, it may be hypothesized that the fetal effects of gestational diabetes mellitus (GDM) with respect to accelerated fetal growth may be less pronounced in twin gestations or alternatively may even have a beneficial role in decreasing the risk of fetal growth restriction in these pregnancies. However, available data are conflicting and are limited by the fact that many of the complications associated with GDM are less relevant for twin gestations, and that all women with GDM included in previous studies were monitored and treated to control maternal blood glucose levels.

OBJECTIVE

We sought to assess the impact of GDM and milder degrees of glucose intolerance on fetal growth and pregnancy outcome in twin pregnancies.

STUDY DESIGN

This was a retrospective cohort study of all women with twin pregnancies who underwent screening for GDM in a single tertiary referral center from October 2003 through December 2014. The diagnosis of GDM during the study period was based on the 2008 Canadian Diabetes Association (CDA) guidelines, which involve universal screening with a 50-g glucose challenge test (GCT) followed by a diagnostic 2-hour 75-g oral glucose tolerance test (OGTT). Fetal growth and pregnancy outcome were compared among 4 groups of women with increasing degree of glucose intolerance: (1) GCT-NEGATIVE, negative 50-g GCT; (2) OGTT-NEGATIVE, positive 50-g GCT followed by a negative 75-g OGTT; (3) GDM-IADPSG, positive 50-g GCT followed by a positive 75-g OGTT according to the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria but not the 2008 CDA criteria-because these women were not considered to have GDM during the study period they were not subjected to any form of treatment; and (4) GDM-CDA, positive 50-g GCT followed by a positive 75-g OGTT according to the 2008 CDA criteria.

RESULTS

Overall 1393 women were eligible for the study: 1021 (73.3%) in the GCT-NEGATIVE group, 184 (13.2%) in the OGTT-NEGATIVE group, 99 (7.1%) in the GDM-IADPSG group, and 89 (6.4%) in the GDM-CDA group. There was a continuous relationship between the degree of glucose intolerance and fetal growth as reflected by a right shift of the distribution curve of birthweight percentiles and a greater likelihood of high birthweight percentile: OGTT-NEGATIVE = odds ratio (OR), 1.5; 95% confidence interval (CI), 1.07-2.2; GDM-IADPSG = OR, 1.7; 95% CI, 1.1-2.6; and GDM-CDA = OR, 1.9, 95% CI, 1.3-3.1 (using the GCT-NEGATIVE group as reference). Fetuses of women with glucose intolerance were more likely to experience asymmetric growth as reflected by an elevated abdominal circumference to head circumference ratio.

CONCLUSION

GDM and milder degrees of glucose intolerance in twin pregnancies are associated with an increased risk of asymmetric overgrowth in a manner that is related to the degree of glucose intolerance.

Disparity in post-treatment maternal circulating magnesium sulfate levels between twin and singleton gestation: Is this the missing link between plurality and adverse outcome?

OBJECTIVE

Magnesium sulfate (MgSO4) administered to women at risk for preterm delivery decreases the risk of cerebral palsy in their children. However, the neuroprotective effect of MgSO4 has not been shown in twin gestations. Thus, the aim of this study was to determine the maternal serum levels of magnesium in twin vs. singleton pregnancies following intravenous treatment of MgSO4.

METHODS

Case control study including two groups of pregnant women who received intravenous MgSO4: (1) twin gestations (n=83) and (2) singleton pregnancies (n=83). Maternal serum magnesium levels 6 and 24 h after initiation of treatment were determined in both groups.

RESULTS

Maternal serum levels of magnesium were significantly lower among patients with twin gestations compared to those with singleton ones 6 h after initiation of treatment (4.6 vs. 4.8 mg/dL, P=0.003). In addition, the rate of pregnant women who obtained therapeutic levels 6 h after initiation of treatment was significantly lower in twin gestations than in singleton ones (36% vs. 58%, P=0.008). Multiple regression analysis revealed that twin gestations were independently and significantly associated with low maternal serum magnesium levels.

CONCLUSIONS

Maternal serum concentrations of magnesium are lower in twin pregnancies than in singleton ones following MgSO4 treatment, which might explain the decreased neuroprotective effect of MgSO4 reported in twin pregnancies.

A clinical opinion on how to manage the risk of preterm birth in twins based on literature review

Twin pregnancies are prone to preterm birth and consequent morbidity. There is an increasing evidence base concerning the prediction and prevention of preterm birth in singletons, including the reduction of morbidity with therapies such as magnesium sulphate and antenatal corticosteroids. However, the research in twins is less clear, partly due to fewer numbers being investigated, but also evidence is largely based on twins without a previous history. Prophylactic interventions such as cerclage, progesterone and vaginal pessaries are increasingly showing benefit in singleton pregnancies with a prior history and when the cervix is short. Cerclage in twins has not been adequately researched in women with previous preterm birth, and as with singletons should not be used on the basis of a short cervix alone. Vaginal progesterone does not work in twins, but its value in high-risk twins, with a prior history and short cervix is uncertain. The vaginal pessary may be valuable in the twin with a short cervix. Currently, it is reasonable to extrapolate some of the evidence from singletons to twins, e.g. with antenatal corticosteroids and magnesium sulphate. Cerclage, vaginal pessaries and progesterone should not be routinely used in twin pregnancies without an additional high-risk factor such as prior history of preterm birth or short cervix, until further evidence is obtained.

Perinatal outcome after fetal reduction from twin to singleton: to reduce or not to reduce?

OBJECTIVE

To determine whether reduction of twin gestation to singleton pregnancy is associated with improved perinatal outcome.

DESIGN

A retrospective cohort study.

SETTING

Single tertiary care medical center.

PATIENT(S)

A cohort of 63 singleton pregnancies after reduction from dichorionic-diamniotic twins gestation and 62 dichorionic-diamniotic nonreduced twins.

INTERVENTION(S)

Fetal reduction between 11 and 14 weeks of gestation.

MAIN OUTCOME MEASURE(S)

Obstetric outcome.

RESULT(S)

The rates of preterm delivery at <34 weeks (1.6% in pregnancies after reduction vs. 11.7% in nonreduced twins) and at <37 weeks of gestation (9.5% vs. 56.7%) were significantly lower in patients whose pregnancies were reduced to singletons. The rates of miscarriage of one twin (0% vs. 4.8%) and early pregnancy loss before 24 weeks of gestation as well as the rates of gestational diabetes (11.1% vs. 10%), hypertensive diseases of pregnancy (6.3% vs. 15%), and intrauterine growth restriction (0% vs. 3.3%) were similar in both groups.

CONCLUSION(S)

Fetal reduction of twins to singleton is associated with a lower risk of prematurity and superior perinatal outcome compared with nonreduced twins. Therefore, the option of fetal reduction should be considered in certain cases of twin pregnancies, where the risk for adverse outcome seems exceptionally high.

Clinical factors affecting the timing of delivery in twin pregnancies

OBJECTIVE

To investigate clinical factors affecting the timing of delivery in twin pregnancies in order to minimize perinatal complications.

METHODS

A retrospective study involved 163 twin pregnancies delivered from January 2006 to September 2011 at Gachon University Gil Medical Center. These cases were divided into three groups based on the delivery timing: less than 32 weeks' gestation (group A), between 32 and 35+6 weeks' gestation (group B), and over 36 weeks' gestation (group C). Clinical factors including maternal age, parity, presence of premature uterine contraction, presence of premature rupture of membrane, white blood cell, high sensitive C-reactive protein level, cervical dilatation, maternal complication, chorionicity, twin specific complication, and perinatal complication were analyzed for each group.

RESULTS

In group B, the timing of delivery was postponed for 14 days or more from the time of admission, and there were fewer numbers of babies with low Apgar score at birth compared with other groups. The frequency of uterine contraction (P<0.001), presence of premature rupture of membranes (P=0.017), dilatation of cervix (P<0.001), increased white blood cell and high sensitive C-reactive protein levels (P=0.002, P<0.001) were important clinical factors during decision making process of delivery timing in twin pregnancies. Twin specific fetal conditions, such as twin-twin transfusion syndrome and discordant growth (over 25% or more) were shown more frequently in group A. However, there were no significant statistical differences among three groups (P=0.06, P=0.14).

CONCLUSION

Proper management for preventing premature contraction and inflammation can be essential in twin pregnancies until 32 weeks' gestation, and may decrease maternal and perinatal complications.

Rapid cervical phIGFBP-1 test in asymptomatic twin pregnancies: role in mid-pregnancy prediction of spontaneous preterm delivery

Objective This study aimed to assess the accuracy of a second-trimester rapid cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) test to predict spontaneous preterm delivery in asymptomatic twin pregnancies. Method During the second trimester, a rapid test to detect phIGFBP-1 in cervical secretions was performed on consecutive twin pregnancies between 2009 and 2011, to evaluate its predictive value for spontaneous preterm delivery at <28, <30, <32 and <34 weeks' gestation. Excluded were patients with cerclage, pessary or undergoing indicated preterm delivery. Results A total of 197 pregnancies fulfilled the study criteria and were tested at a median gestational age of 20.3 weeks (interquartile range: 20-20.6). Median gestational age at delivery was 36.4 weeks. Spontaneous preterm delivery at <34 weeks occurred in 21 (10.7%) cases, at <32 weeks in 9 (4.5%), at <30 weeks in 6 (3%) and at <28 weeks in 4 (2%). Seventeen patients (8.7%) were test positive: In this group, three patients delivered before 34 weeks' gestation, whereas none delivered at <32 weeks. The sensitivity, specificity, positive and negative predictive value of the test for spontaneous preterm delivery <34 weeks were 14% (95% confidence interval, 3-37%), 92% (86-95%), 17% (4-44%) and 90% (84-93%), respectively, with a positive and negative likelihood ratio of 1.79 (0.56-5.74) and 0.93 (0.78-1.10). Conclusions In the second trimester, rapid cervical phIGFBP-1 testing in asymptomatic twin pregnancies has a poor performance in predicting spontaneous preterm delivery.

Short cervix syndrome: current knowledge from etiology to the control

BACKGROUND

Preterm delivery is one of the most serious public health problems and is the most important factor relating to neonatal morbidity and mortality. The strategies for preventing it include understanding the risk factors, with specific interventions. Recently, uterine cervix measurements using ultrasonography and vaginal administration of progesterone have gained importance in predicting and secondarily preventing spontaneous preterm delivery.

OBJECTIVE

To describe the short cervix syndrome, including its etiology, diagnosis, and possible therapies.

METHODS

Research in ISI, Pubmed, and Scielo database using the words short cervix, preterm delivery, sludge, cervical funneling, cervical gland area, progesterone, cerclage, and pessary.

RESULTS

We found a lot of articles about this topic, including randomized controlled trials. The etiology is multifactorial, being the diagnosis based in a cervix shortening at 20-24 weeks. The history and measurement of cervix length by transvaginal ultrasound have been shown to be effective to select the high risk pregnancies. The progesterone, cervical cerclage, and cervical pessary showed to be effective to reduce the preterm delivery in pregnant women with short cervix.

CONCLUSION

The successful management of pregnant women presenting a short cervix depends on the understanding that cervical shortening is the final common path for several causes of preterm delivery. The best approach should be individualized to each patient.