FIGO Working Group on Good Clinical Practice in Maternal-Fetal Medicine. Good clinical practice advice: Management of twin pregnancy

Management of twin pregnancies: Remaining challenges and unanswered questions

Several professional societies have published guidelines on twin pregnancies over the past few years. These documents provide recommendations on antenatal surveillance and management of twin pregnancies. At the same time, these guidelines identify several key areas where evidence is limited and additional research is needed. In the present review, we summarize available evidence regarding some of these key areas, including the screening and prevention of preterm birth, the definition and management of fetal growth restriction, the diagnosis and management of gestational diabetes, the optimal maternal gestational weight gain, and the mode and timing of delivery. In addition, we describe several online tools related to these areas that can empower individuals with twin pregnancies and assist care providers in counseling these patients.

Specific growth velocity reference charts for monochorionic twin pregnancies

OBJECTIVE

We aimed to create specific growth velocity reference charts for monochorionic (MC) twin pregnancies and provide additional information for assessing fetal growth in MC twins.

STUDY DESIGN

This retrospective study collected data from uncomplicated MC twins with serial ultrasound parameters. The four ultrasound parameters, including biparietal diameter, femur length, head circumference, and abdominal circumference, were used to calculate the estimated fetal weight (EFW). Multilevel linear regression models were applied to fit growth velocity charts for each biometric parameter and EFW. Analysis of variance was used to examine differences in birthweight by whether EFW velocity and EFW values were <10th or ≥10th percentiles.

RESULTS

The final analysis encompassed a total of 5956 ultrasound examinations conducted on 487 MC twins. The growth velocity of four biparietal diameters exhibited a gradual decrease in a nearly linear fashion progressing from 18 to 37 gestational weeks. The EFW velocity increased steadily from 18 to 36 gestational weeks, reaching a peak of 178.2 g/week, and then the velocity gradually decreased until delivery. At 32 weeks for illustration, the lightest birth weight was observed when both EFW and EFW velocity were <10th percentile (1899 g). The study also found that birth weight was higher when EFW velocity was ≥10th percentile compared with <10th percentile, regardless of EFW being below or above the 10th percentile (2263 and 1906 g, respectively; P < 0.001).

CONCLUSION

We developed specific growth velocity reference charts for MC twins, which could provide a valuable reference point for a more precise evaluation of fetal growth in MC twins. Preliminary findings indicate that the inclusion of fetal growth velocity in monitoring fetal growth provides additional information beyond EFW alone.

Maternal and fetal outcomes after planned cesarean or vaginal delivery in twin pregnancy: a comparison between 2 third level birth centers

BACKGROUND

Twin pregnancy is associated with higher risks of adverse perinatal outcomes for both the mother and the babies. Among the many challenges in the follow-up of twin pregnancies, the mode of delivery is the last but not the least decision to be made, with the main influencing factors being amnionicity and fetal presentation. The aim of the study was to compare perinatal outcomes in two European centers using different protocols for twin birth in case of non-cephalic second twin; the Italian patients being delivered mainly by cesarean section with those in Belgium being routinely offered the choice of vaginal delivery (VD).

METHODS

This was a dual center international retrospective observational study. The population included 843 women with a twin pregnancy ≥ 32 weeks (dichorionic or monochorionic diamniotic pregnancies) and a known pregnancy outcome. The population was stratified according to chorionicity. Demographic and pregnancy data were reported per pregnancy, whereas neonatal outcomes were reported per fetus. We used multiple logistic regression models to adjust for possible confounding variables and to compute the adjusted odds ratio (adjOR) for each maternal or neonatal outcome.

RESULTS

The observed rate of cesarean delivery was significantly higher in the Italian cohort: 85% for dichorionic pregnancies and 94.4% for the monochorionic vs 45.2% and 54.4% respectively in the Belgian center (p-value < 0.001). We found that Belgian cohort showed significantly higher rates of NICU admission, respiratory distress at birth and Apgar score of < 7 after 5 min. Despite these differences, the composite severe adverse outcome was similar between the two groups.

CONCLUSION

In this study, neither the presentation of the second twin nor the chorionicity affected maternal and severe neonatal outcomes, regardless of the mode of delivery in two tertiary care centers, but VD was associated to a poorer short-term neonatal outcome.

Intrapartum Ultrasound Guidance to Make Safer Any Obstetric Intervention: Fetal Head Rotation, Assisted Vaginal Birth, Breech Delivery of the Second Twin

Intrapartum ultrasound (US) is more reliable than clinical assessment in determining parameters of crucial importance to optimize the management of labor including the position and station of the presenting part. Evidence from the literature supports the role of intrapartum US in predicting the outcome of labor in women diagnosed with slow progress during the first and second stage of labor, and randomized data have demonstrated that transabdominal US is far more accurate than digital examination in assessing fetal position before performing an instrumental delivery. Intrapartum US has also been shown to outperform the clinical skills in predicting the outcome and improving the technique of instrumental vaginal delivery. On this basis, some guidelines recommend intrapartum US to ascertain occiput position before performing an instrumental delivery. Manual rotation of occiput posterior position (MROP) and assisted breech delivery of the second twin are other obstetric interventions that can be performed during the second stage of labor with the support of intrapartum US. In this review article we summarize the existing evidence on the role of intrapartum US in assisting different types of obstetric intervention with the aim to improve their safety.

Comparison of perinatal outcome and mode of birth of twin and singleton pregnancies in migrant and refugee populations on the Thai Myanmar border: A population cohort

BACKGROUND

In low- and middle-income countries twin births have a high risk of complications partly due to barriers to accessing hospital care. This study compares pregnancy outcomes, maternal and neonatal morbidity and mortality of twin to singleton pregnancy in refugee and migrant clinics on the Thai Myanmar border.

METHODS

A retrospective review of medical records of all singleton and twin pregnancies delivered or followed at antenatal clinics of the Shoklo Malaria Research Unit from 1986 to 2020, with a known outcome and estimated gestational age. Logistic regression was done to compare the odds of maternal and neonatal outcomes between twin and singleton pregnancies.

RESULTS

Between 1986 and 2020 this unstable and migratory population had a recorded outcome of pregnancy of 28 weeks or more for 597 twin births and 59,005 singleton births. Twinning rate was low and stable (<9 per 1,000) over 30 years. Three-quarters (446/597) of the twin pregnancies and 96% (56,626/59,005) of singletons birthed vaginally. During pregnancy, a significantly higher proportion of twin pregnancies compared to singleton had pre-eclampsia (7.0% versus 1.7%), gestational hypertension (9.9% versus 3.9%) and eclampsia (1.0% versus 0.2%). The stillbirth rate of twin 1 and twin 2 was higher compared to singletons: twin 1 25 per 1,000 (15/595), twin 2 64 per 1,000 (38/595) and singletons 12 per 1,000 (680/58,781). The estimated odds ratio (95% confidence interval (CI)) for stillbirth of twin 1 and twin 2 compared to singletons was 2.2 (95% CI 1.3-3.6) and 5.8 (95% CI 4.1-8.1); and maternal death 2.0 (0.95-11.4), respectively, As expected most perinatal deaths were 28 to <32 week gestation.

CONCLUSION

In this fragile setting where access to hospital care is difficult, three in four twins birthed vaginally. Twin pregnancies have a higher maternal morbidity and perinatal mortality, especially the second twin, compared to singleton pregnancies.

Cervical length as a screening tool for preterm birth in twin pregnancies: a systematic review and critical evaluation of quality clinical practice guidelines

OBJECTIVES

Twin pregnancies are at increased risk of preterm birth (PTB) compared to singletons. Evaluation of cervical length (CL) represents the optimal tool to screen PTB in singleton. Conversely, there is less evidence on the use of CL in twins. Our aim was to evaluate the methodological quality and clinical heterogeneity of clinical practice guidelines (CPGs) on the CL application in twins using AGREE II methodology.

METHODS

MEDLINE, Scopus, and websites of the main scientific societies were examined. The following aspects were evaluated: diagnostic accuracy of CL, optimal gestational age at assessment and interventions in twin pregnancies with reduced CL. The quality of the published CPGs was carried out using "The Appraisal of Guidelines for REsearch and Evaluation (AGREE II)" tool. The quality of guideline was rated using a scoring system. Each considered item was evaluated by the reviewers on a seven-point scale that ranges from 1 (strongly disagree) to 7 (strongly agree). A cut-off >60 % identifies a CPGs as recommended.

RESULTS

The AGREE II standardized domain scores for the first overall assessment had a mean of 74 %. The score was more than 60 % in the 66.6 % of CPGs analyzed indicating an agreement between the reviewers on recommending the use of these CPGs. A significant heterogeneity was found; there was no specific recommendation on CL assessment in about half of the published CPGs. There was also significant heterogeneity on the CL cut-off to prompt intervention.

CONCLUSIONS

Despite the fact that the AGREE II analysis showed that the majority of the included guidelines are of good quality, there was a significant heterogeneity among CPGs as regard as the indication, timing, and cut-off of CL in twins as well as in the indication of interventions.

Preterm Birth: Screening and Prediction

Preterm birth (PTB) affects approximately 10% of births globally each year and is the most significant direct cause of neonatal death and of long-term disability worldwide. Early identification of women at high risk of PTB is important, given the availability of evidence-based, effective screening modalities, which facilitate decision-making on preventative strategies, particularly transvaginal sonographic cervical length (CL) measurement. There is growing evidence that combining CL with quantitative fetal fibronectin (qfFN) and maternal risk factors in the extensively peer-reviewed and validated QUanititative Innovation in Predicting Preterm birth (QUiPP) application can aid both the triage of patients who present as emergencies with symptoms of preterm labor and high-risk asymptomatic women attending PTB surveillance clinics. The QUiPP app risk of delivery thus supports shared decision-making with patients on the need for increased outpatient surveillance, in-patient treatment for preterm labor or simply reassurance for those unlikely to deliver preterm. Effective triage of patients at preterm gestations is an obstetric clinical priority as correctly timed administration of antenatal corticosteroids will maximise their neonatal benefits. This review explores the predictive capacity of existing predictive tests for PTB in both singleton and multiple pregnancies, including the QUiPP app v.2. and discusses promising new research areas, which aim to predict PTB through cervical stiffness and elastography measurements, metabolomics, extracellular vesicles and artificial intelligence.

Reduction in spontaneous and iatrogenic preterm births in twin pregnancies during COVID-19 lockdown in Melbourne, Australia: a multicenter cohort study

BACKGROUND

Melbourne, Australia, recorded one of the longest and most stringent pandemic lockdowns in 2020, which was associated with an increase in preterm stillbirths among singleton pregnancies. Twin pregnancies may be particularly susceptible to the impacts of pandemic disruptions to maternity care due to their higher background risk of adverse perinatal outcomes.

METHODS

Multicenter retrospective cohort study of all twin pregnancies birthing in public maternity hospitals in Melbourne. Multivariable log-binomial regression models were used to compare perinatal outcomes between a pre-pandemic group to women in whom weeks 20+0 to 40+0 of gestation occurred entirely during one of two lockdown-exposure periods: exposure 1 from 22 March 2020 to 21 March 2021 and exposure 2 from 22 March 2021 to 27 March 2022.

RESULTS

Total preterm births < 37 weeks were significantly lower in exposure 1 compared with the pre-pandemic period (63.1% vs 68.3%; adjusted risk ratio 0.92 95% CI 0.87-0.98, p = 0.01). This was mainly driven by fewer spontaneous preterm births (18.9% vs 20.3%; adjusted risk ratio 0.95 95% CI 0.90-0.99, p = 0.04). There were also lower rates of preterm birth < 34 weeks (19.9% vs 23.0%, adjusted risk ratio 0.93 95% CI 0.89-0.98 p = 0.01) and total iatrogenic births for fetal compromise (13.4% vs 20.4%; adjusted risk ratio 0.94 95% CI 0.89-0.98, p = 0.01). There were fewer special care nursery admissions (38.5% vs 43.4%; adjusted risk ratio 0.91 95% CI 0.87-0.95, p < 0.001) but no significant changes in stillbirth (1.5% vs 1.6%; adjusted risk ratio 1.00 95% CI 0.99-1.01, p = 0.82). Compared with the pre-pandemic period, there were more preterm births < 28 weeks and neonatal intensive care unit admissions in exposure 2.

CONCLUSIONS

Melbourne's first lockdown-exposure period was associated with lower preterm births in twins without significant differences in adverse newborn outcomes. Our findings provide insights into the influences on preterm birth and the optimal timing of delivery for twins.

National and international guidelines on the management of twin pregnancies: a comparative review

Twin gestations are associated with increased risk of pregnancy complications. However, high-quality evidence regarding the management of twin pregnancies is limited, often resulting in inconsistencies in the recommendations of various national and international professional societies. In addition, some recommendations related to the management of twin gestations are often missing from the clinical guidelines dedicated to twin pregnancies and are instead included in the practice guidelines on specific pregnancy complications (eg, preterm birth) of the same professional society. This can make it challenging for care providers to easily identify and compare recommendations for the management of twin pregnancies. This study aimed to identify, summarize, and compare the recommendations of selected professional societies from high-income countries on the management of twin pregnancies, highlighting areas of both consensus and controversy. We reviewed clinical practice guidelines of selected major professional societies that were either specific to twin pregnancies or were focused on pregnancy complications or aspects of antenatal care that may be relevant for twin pregnancies. We decided a priori to include clinical guidelines from 7 high-income countries (United States, Canada, United Kingdom, France, Germany, and Australia and New Zealand grouped together) and from 2 international societies (International Society of Ultrasound in Obstetrics and Gynecology and the International Federation of Gynecology and Obstetrics). We identified recommendations regarding the following care areas: first-trimester care, antenatal surveillance, preterm birth and other pregnancy complications (preeclampsia, fetal growth restriction, and gestational diabetes mellitus), and timing and mode of delivery. We identified 28 guidelines published by 11 professional societies from the 7 countries and 2 international societies. Thirteen of these guidelines focus on twin pregnancies, whereas the other 16 focus on specific pregnancy complications predominantly in singletons but also include some recommendations for twin pregnancies. Most of the guidelines are recent, with 15 of the 29 guidelines published over the past 3 years. We identified considerable disagreement among guidelines, primarily in 4 key areas: screening and prevention of preterm birth, using aspirin to prevent preeclampsia, defining fetal growth restriction, and the timing of delivery. In addition, there is limited guidance on several important areas, including the implications of the "vanishing twin" phenomenon, technical aspects and risks of invasive procedures, nutrition and weight gain, physical and sexual activity, the optimal growth chart to be used in twin pregnancies, the diagnosis and management of gestational diabetes mellitus, and intrapartum care.This consolidation of key recommendations across several clinical practice guidelines can assist healthcare providers in accessing and comparing recommendations on the management of twin pregnancies and identifies high-priority areas for future research based on either continued disagreement among societies or limited current evidence to guide care.

A cross-sectional survey of women's views and preferences for preterm birth screening and treatment

OBJECTIVES

Primary outcomes were to determine; 1) the desire for more patient information from healthcare professionals on preterm birth (PTB) prevention 2) the desire for PTB screening surveillance or participation in research or 3) the acceptability of transvaginal ultrasound (TVUS) or vaginal examinations to predict spontaneous PTB.

METHODS

A 19-question, piloted, self-administered survey was completed by unselected pregnant women in a tertiary maternity hospital in Dublin, Ireland. Data was collected to include maternal socio-demographics, past obstetric history, and current pregnancy details, in addition to views and preferences on PTB screening and preventative treatments. Statistical analysis to include binary and multinomial regression was performed by IBM SPSS Statistics for Windows (Version 29.0).

RESULTS

277 women completed the study survey. 9.4% of women had attended the preterm birth surveillance clinic (PSC). 75.1% of respondents indicated a preference for more information from healthcare professionals about PTB. 65% reported that TVUS and vaginal examinations were acceptable in pregnancy. The acceptability of antenatal examinations was significantly influenced by ethnicity; white European (OR 2.58, CI 1.12-5.95, p = 0.003) and Asian (OR 3.39, CI 1.18-9.67, p = 0.02). Discomfort (25.3%) and vaginal bleeding (11.9%) were the most frequently reported concerns about TVUS. 95.7% of unselected women indicated that they would accept treatment to prevent PTB. Vaginal progesterone (53.8%) was preferred treatment compared to cervical cerclage (15.9%) or cervical pessary (16.6%). 55.6% of respondents stated they attend or wish to attend for additional appointments or research opportunities for PTB screening. Women with a previous PTB or second trimester miscarriage were more likely to attend or wish to attend for PTB screening (OR 3.23, CI 1.34-7.79, p = 0.009).

CONCLUSION

PTB is an important healthcare priority for pregnant women in Ireland. However, women require more information, counselling and reassurance about the utility and safety of TVUS in PSCs.

Classification and Special Nutritional Needs of SGA Infants and Neonates of Multiple Pregnancies

Data regarding the nutritional management of preterm small for gestational age (SGA) infants are scarce. In the recent report of ESPGHAN, the recommended energy for very preterm infants during hospitalization has been increased, yet this may not fit the needs of all preterm infants. It is important to distinguish fetal growth-restricted (FGR) infants from constitutional SGA infants, as well as preterm SGA from preterm AGA infants, since they may have different nutritional needs. Preterm FGR infants, and specifically infants < 29 weeks' gestation, accumulate nutrient deficits due to intrauterine malnutrition, prematurity, morbidities, delayed initiation of feeding, and feeding intolerance. Therefore, these infants may need more aggressive nutrition for optimal catch-up growth and neurologic development. However, a balance should be kept between optimal and excessive catch-up growth, since the combination of intrauterine malnutrition and excessive postnatal growth has been linked with later adverse metabolic consequences. Furthermore, multiple gestation is often complicated by FGR and prematurity. There is controversy in the definition of FGR in multiple gestations, and it should be noted that FGR in multiple gestation usually differs etiologically from FGR in singletons. The aim of this review is to summarize existing knowledge regarding the nutritional needs of preterm FGR and FGR infants of multiple gestation.

Neonatal and maternal outcomes with elective cesarean section compared to induction of labor in twin pregnancies: A prospective cohort study

OBJECTIVES

The aim of this study was to compare neonatal and maternal outcomes in twin pregnancies with elective cesarean section (ECS) and induction of labor (IOL) to better inform women during the counselling process.

MATERIALS AND METHODS

We conducted a cohort study including all twin pregnancies referred to the Department of Obstetrics at Kolding University Hospital, Denmark between January 2007 to April 2019 (n = 819). The primary analysis compared maternal and neonatal outcomes in pregnancies planned for IOL with those planned for ECS after week 34. A secondary analysis compared maternal and neonatal outcomes in pregnancies who underwent IOL followed by successful vaginal delivery with outcomes in those who underwent ECS.

RESULTS

Among 587 eligible twin pregnancies, the rates of unplanned CS did not differ between those planned for ECS compared to those planned for IOL (38% vs. 33%; p = 0.27). IOL resulted in successful vaginal delivery in 67% (155/231) of those planned for IOL. Maternal outcomes did not differ between women who were planned for, or received, delivery with either IOL or ECS. Regarding neonatal outcomes, significantly more neonates required treatment with C-PAP in ECS group, than in the IOL group, and a higher median number of maturity days among mothers planned for ECS. However, no other significant difference in neonatal outcomes was observed when comparing successful IOL with successful ECS.

CONCLUSION

Induction of labor was not associated with worse outcomes compared to elective caesarean section in this large cohort of routinely handled twin pregnancies. In women with twin pregnancies indicated for delivery, who does not go into spontaneous labor, induction of labor is a safe option for both the mothers and their neonates.

Clinical practice guidelines for the antenatal management of dichorionic diamniotic twin pregnancies: a systematic review

OBJECTIVE

This review aimed to identify guidelines with recommendations applicable to the antenatal management of dichorionic diamniotic twin pregnancies within high-income countries, appraise their methodological quality, and discuss the similarities and variability across guidelines.

METHOD

A systematic literature review of electronic databases was performed. Manual searches of guideline repositories and websites of professional organisations were performed to identify additional guidelines. The protocol for this systematic review was registered on PROSPERO (CRD42021248586, 25 June 2021). AGREE II and AGREE-REX tools were applied to assess the quality of eligible guidelines. A narrative and thematic synthesis described and compared the guidelines and their recommendations.

RESULTS

Twenty-four guidelines were included, from which 483 recommendations were identified across 4 international organisations and 12 countries. Guidelines addressed eight themes and recommendations were classified accordingly: chorionicity and dating (103 recommendations), fetal growth (105 recommendations), termination of pregnancy (12 recommendations), fetal death (13 recommendations), fetal anomalies (65 recommendations), antenatal care (65 recommendations), preterm labour (56 recommendations) and birth (54 recommendations). Guidelines showed significant variability in recommendations, with conflicting recommendations regarding non-invasive preterm testing, definitions surrounding selective fetal growth restriction, screening for preterm labour and the timing of birth. Guidelines lacked a focus on standard antenatal management of DCDA twins, management of discordant fetal anomaly and single fetal demise.

CONCLUSIONS

Specific guidance for dichorionic diamniotic twins is overall indistinct and access to guidance regarding the antenatal management of these pregnancies is currently difficult. Management of discordant fetal anomaly or single fetal demise needs greater consideration.

Mode of delivery of Finnish dichorionic and monochorionic-diamniotic twins: A retrospective observational study including a risk score for intrapartum cesarean birth

Background and Aims

Trial of labor is considered safe also among twins, yet nearly 50% are born via cesarean section in Finland. While planned cesarean births have declined among twins, intrapartum cesarean deliveries have risen, postulating evaluation of criteria for trial of labor. The objective of this study was to create an outline of the mode of delivery of dichorionic and monochorionic-diamniotic Finnish twins. By evaluating risk factors for intrapartum cesarean delivery (CD), we aimed at creating a risk score for intrapartum cesarean birth for twins.

Methods

A retrospective observational study based on a cohort of dichorionic and monochorionic-diamniotic twin pregnancies considered as candidates for trial of labor in 2006, 2010, 2014, and 2018 (n = 720) was performed. Differences between parturients with vaginal delivery and intrapartum CD to identify potential risk factors for intrapartum CD were assessed. Logistic regression analysis (n = 707) was used to further define risk score points for recognized risk factors.

Results

A total of 23.8% (171/720, 95% confidence interval [CI] = 20.7-26.9) of parturients experienced intrapartum CD. Induction of labor, primiparity, fear of childbirth, artificial reproductive technology, higher maternal age, and other than cephalic/cephalic presentation independently associated with intrapartum CD. The achieved total risk score ranged from 0 to 13 points with significantly higher points among the CD group (6.61 vs. 4.42, p < 0.001). Using ≥8 points as a cut-off, 51.4% (56/109) were delivered by intrapartum CD (sensitivity = 33.73%, specificity = 90.20%, positive predictive value = 51.38%, negative predictive value = 81.61%). The total risk score had a fair predictive capability for intrapartum CD (area under the curve = 0.729, 95% CI = 0.685-0.773).

Conclusion

Fair-level risk stratification could be achieved with higher maternal age, primiparity, induction of labor, artificial reproductive technology, fear of childbirth, and other than cephalic/cephalic presentation increasing the risk. Parturients with low-risk score (0-7 points) appear to be the best candidates for trial of labor with acceptable CD rates in this group (18.4%).

Effectiveness of dinoprostone gel, misoprostol vaginal insert and dinoprostone vaginal insert for induction of labour in twin pregnancies

OBJECTIVES

To compare the effectiveness and safety of Dinoprostone Gel (DG), Misoprostol Vaginal Insert (MVI) and Dinoprostone Vaginal Insert (DVI) for induction of labour (IOL) in twin pregnancies.

STUDY DESIGN

Retrospective cohort study of twin pregnancies > 34 + 0 weeks gestation that underwent induction of labour (IOL) with DG, MVI or DVI between December 2016 and November 2019 in a Tertiary NHS hospital, North West England, UK. Delivery characteristics, maternal complications and neonatal outcomes were compared between the three groups.

RESULTS

A total of 87 twin pregnancies were included for analysis. 27 women received DG, 34 received MVI and 26 DVI. The MVI cohort had a higher proportion of nulliparous women (55.9%) compared to the DG and DVI cohorts, 29.6% and 38.5% respectively. No other differences amongst demographic characteristics were considered clinically significant. DG demonstrated a significantly quicker time to delivery (minutes) compared to DVI (1021 ± 556 versus 1649 ± 852; P = 0.0026). Significantly fewer women required terbutaline for hyperstimulation/tachysystole in the DG group compared to MVI (0% vs 32%; RR 0.05; 95% CI 0.003-0.88). Both DG and MVI groups required significantly less oxytocin following artificial rupture of membranes compared to DVI (33% vs 65%; RR 0.51; 95% CI 0.28-0.93) and (29% vs 65%; RR 0.45; 95% CI 0.25-0.81). There were no significant differences in mode of delivery, maternal complications and neonatal outcomes.

CONCLUSION

Our data suggests that for women with a twin pregnancy considering a planned labour that induction with DG, MVI and DVI appear to be equally safe and effective IOL methods. These results should be interpreted with caution due to the study being underpowered to detect significant adverse outcomes. In order to determine the optimal method of IOL in twins, direct randomised comparison is needed.

Nomogram to predict postpartum hemorrhage in cesarean delivery for twin pregnancies: a retrospective cohort study in China

Background

Postpartum hemorrhage (PPH) is the most common cause of maternal morbidity and mortality worldwide. A reliable risk assessment tool for PPH could optimize available interventions to reduce adverse maternal outcomes.

Objective

The objective of this study was to explore a nomogram predicting the risk of postpartum hemorrhage after cesarean delivery for twin pregnancies.

Methods

This single-center retrospective cohort study conducted twin pregnancies who underwent cesarean delivery between January 2014 and July 2021. Propensity score matching at baseline was used to match PPH (blood loss ≥1000 mL) and non-PPH group (blood loss <1000 mL). A nomogram was developed to predict the risk of PPH in cesarean delivery for twin pregnancies. The receiver operating characteristic curve (ROC), calibration plot, and decision curve analysis (DCA) were, respectively, used to evaluate the discrimination, calibration, and clinical utility of the prediction models.

Results

After propensity score matching, 186 twin pregnancies in the PPH group were matched with 186 controls in the non-PPH group. Seven independent prognostic variables, including antepartum albumin, assisted reproductive technology, hypertensive disorders of pregnancy, placenta previa, placenta accrete spectrum, intrapartum cesarean delivered, and estimated weights of twins, were used to build the nomogram. Based on the performance of the model, it appears that a good calibration (Hosmer-Lemeshow χ2 = 4.84, P > 0.05), an excellent predictive ability (area under the curve: 0.778, 95% CI: 0.732-0.825), and a good positive net benefit in the predictive model have been achieved.

Conclusion

The nomogram was first generated to predict PPH in cesarean delivery for twin pregnancies, which could help clinicians to provide a reference for the preoperative surgical plan, choose optimal treatments, optimize healthcare resources, and thereby reduce the associated adverse maternal outcomes.

Cerebro-placental and umbilico-cerebral ratios in uncomplicated monochorionic twins: Longitudinal references and comparison with singletons

OBJECTIVES

Monochorionic twins (MC) are at high risk of adverse outcomes and Doppler investigation of umbilical and cerebral flows is mandatory for their surveillance. The cerebro-placental (CPR) and umbilico-cerebral (UCR) ratios are considered non-invasive measures of fetal adaptation to hypoxemia. We aimed to provide longitudinal references for CPR and UCR from 16 to 37 weeks of gestation that are specific for MC twins, and compare these with singleton charts.

METHODS

Longitudinal study of a cohort of consecutive uncomplicated MC twin pregnancies monitored at our unit from 2010 to 2018. The estimated centile curves were obtained estimating the median with fractional polynomials by a multilevel model and the external centiles through the residuals. The comparison with singletons references was made through graphic evaluation.

RESULTS

One-hundred-fifty-two MC pregnancies were included with a median of 10 longitudinal ultrasounds each. References for CPR and UCR in function of gestational age are presented. Compared to singletons, MC twins showed an earlier and greater circulatory redistribution with lower CPR and higher UCR median values.

CONCLUSIONS

MC twin-specific references for CPR and UCR suitable for serial monitoring are presented. The comparison with singleton references demonstrates substantial differences in the hemodynamic balance that must be considered when interpreting findings in MC twins. This article is protected by copyright. All rights reserved.

Perinatal outcome of dichorionic and monochorionic-diamniotic Finnish twins: a historical cohort study

INTRODUCTION

Although the perinatal mortality of monochorionic twins has been reported to be higher, the role of chorionicity is debated and data from Finland are still lacking. To examine the effect of chorionicity on the main outcome measures, perinatal and neonatal mortality and neonatal morbidity of Finnish twins, a comprehensive population-based historical cohort study was performed at Helsinki University Hospitals.

MATERIAL AND METHODS

All 1034 dichorionic and monochorionic-diamniotic twin pregnancies managed at Helsinki University Hospital area during 2006, 2010, 2014 and 2018 were collected from patient databases. Information on chorionicity was retrieved from ultrasound reports and all relevant clinical information from patient records. Differences in perinatal and neonatal mortality and neonatal morbidity were analyzed by performing group comparisons between the twins and chorionicity. The role of chorionicity was also assessed in logistic regression analyses.

RESULTS

There were 1034 dichorionic-diamniotic (DCDA, n = 789, 76.3%, 95% confidence interval [CI] 73.6-78.9) and monochorionic-diamniotic (MCDA, n = 245, 23.7%, 95% CI 21.4-26.0) twin pregnancies during the studied years. Most (n = 580, 56.1%, 95% CI 52.8-59.2) twins were born at term, but 151 (61.6%, 95% CI 55.8-67.3) of MCDA twins were preterm and had lower birthweight and Apgar scores and higher risk of death of one twin. Perinatal and neonatal mortality did not differ between twins A and B, but the immediate outcome of twin B was worse, with lower arterial pH and Apgar scores and increased need of neonatal intensive care unit treatment.

CONCLUSIONS

Chorionicity contributes to the perinatal and neonatal outcome in favor of dichorionic twins. This disadvantage of MCDA twinning is likely explained by earlier gestational age at birth and inequal placental sharing. Irrespective of chorionicity, twin B faces more complications.

Twin-twin transfusion syndrome and the definition of recipient polyhydramnios

BACKGROUND

Controversy exists regarding the threshold of recipient twin polyhydramnios required to diagnose twin-twin transfusion syndrome at a gestational age of ≥20 weeks. One criterion set (Quintero staging) requires the amniotic fluid maximum vertical pocket for the recipient twin to measure ≥8 cm, whereas another (European) system uses a maximum vertical pocket for the recipient twin of ≥10 cm.

OBJECTIVE

This study aimed to characterize the patients with twin-twin transfusion syndrome who were treated with laser surgery and would be excluded from laser surgery according to the European criteria.

STUDY DESIGN

A total of 366 monochorionic diamniotic twins diagnosed with twin-twin transfusion syndrome from 20 to 26 weeks' gestation who underwent laser surgery at our center were studied. A maximum vertical pocket for the recipient twin of ≥8 cm was used to diagnose twin-twin transfusion syndrome. Patients were retrospectively divided into the following 2 groups: group A with a maximum vertical pocket for the recipient twin of ≥8 cm and <10 cm and group B with a maximum vertical pocket for the recipient twin of ≥10 cm. The association of each of the groups with the survivorship outcomes was tested. Bivariate associations between the patient characteristics and the 30-day donor twin and dual survivorship outcomes were evaluated. Tests used in the analysis were chi-square or Fisher exact tests as appropriate for categorical variables and Kruskal-Wallis tests for continuous variables. Multiple logistic regression models for each of the survivorship outcomes were then assessed. The results are reported as mean±standard deviation.

RESULTS

Of the 366 studied patients, 53 (14.5%) had a maximum vertical pocket for the recipient twin of ≥8 and <10 cm (group A) and 313 (85.5%) had a maximum vertical pocket for the recipient twin of ≥10 cm (group B). Groups A and B did not differ in the Quintero stage. Notably, 60.4% (32 of 53) of group A patients were stage III or IV. When compared with group B, group A was diagnosed with twin-twin transfusion syndrome at an earlier gestational age (21.7±1.6 vs 22.3±1.6 weeks; P=.0037) and had a higher prevalence of donor growth restriction (81.1% [43 of 53] vs 65.5% [205 of 313]; P=.0260). Rates of at least 1 twin and dual twin survival between group A and B were similar (98.1% [52 of 53] vs 95.8% [300 of 313]; P=.7023, and 79.2% [42 of 53] vs 83.4% [261 of 313]; P=.4369, respectively). Logistic regression models adjusted for perioperative characteristics showed no difference in the outcomes between the groups (group B as reference) (donor twin survival odds ratio, 0.64; 95% confidence interval, 0.29-1.42; P=.2753; and dual survivor odds ratio, 0.90; 95% confidence interval, 0.42-1.91; P=.7757).

CONCLUSION

Restriction of the definition of twin-twin transfusion syndrome to a maximum vertical pocket for the recipient of ≥10 cm beyond 20 weeks gestational age would potentially exclude 14.5% of patients from laser surgery, the majority of whom had advanced stage twin-twin transfusion syndrome. A unifying criterion of a maximum vertical pocket for the recipient of ≥8 cm regardless of gestational age would allow inclusion of these patients and access to surgical management.

Labour induction in twin pregnancies

Medically-indicated deliveries are common in twin pregnancies given the increased risk of various obstetric complications in twin compared to singleton pregnancies, mainly hypertensive disorders of pregnancy and foetal growth restriction. Due to the unique characteristics of twin pregnancies, the success rates and safety of labour induction may be different than in singleton pregnancies. However, while there are abundant data regarding induction of labour in singleton pregnancies, the efficacy and safety of labour induction in twin pregnancies have been far less studied. In the current manuscript we summarize available data on various aspects of labour induction in twin pregnancies including incidence, success rate, prognostic factors, safety and methods for labour induction in twins. This information may assist healthcare providers in counselling patients with twin pregnancies when labour induction is indicated.

Performance of the cervical shortening for prediction of spontaneous preterm birth in uncomplicated twins

OBJECTIVE

There is a lack of consensus about the management of twins with significant cervical length (CL) shortening, especially if CL is above 25 mm. Therefore, it is important to define "abnormal" CL change over time, and to compare the performance of different strategies. The aim of this study was twofold, to describe the performance of the cervical shortening and that of an integrated strategy that includes both the cervical shortening and a fixed CL cutoff <25 mm in any measurement as predictor of spontaneous PTB (sPTB) < 34 weeks in uncomplicated twin pregnancies.

MATERIAL AND METHODS

Retrospective cohort study of twins followed in our Twins Clinic at Hospital Italiano de Buenos Aires from 2013 to 2017. Inclusion criteria were dichorionic or monochorionic diamniotic twins with CL measurement between 18 and 33 + 6 weeks with available data of the delivery. Exclusion criteria included any of the following complications: iatrogenic preterm delivery <34 weeks, cerclage, fetal growth restriction, fetal death, structural anomalies, polyhydramnios, twin-twin transfusion syndrome, selective fetal growth restriction, twin anemia-polycythemia sequence, and twin reversed arterial perfusion sequence. Spontaneous preterm birth was defined as spontaneous delivery <34 weeks. Cervical shortening was analyzed in the following periods: 20-24 weeks, 20-28 weeks, 24-28 weeks, 24-32 weeks and 28-32 weeks. Cervical changes were analyzed as velocity of shortening over time (mm/week) and as the ratio of shortening over time (%/week). ROC curves for each period were constructed and two different cutoffs were used to classify changes of the CL as positive or negative screening: a) the shortening of CL associated to the highest value of the Youden Index and b) fixing a 10% false positive rate (FPR). For the second objective, we analyzed an integrated strategy considering a fixed cutoff of 25 mm at any GA and/or a significant shortening. The screening was considered positive if any CL measurement was <25 mm at any GA or there was a shortening of the CL ≥ the cutoff obtained for each period. We report sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratio and area under the ROC curve.

RESULTS

We included 378 patients and 1417 measurements, 284 (75%) dichorionic and 94 (25%) monochorionic. Between 20 and 28 weeks, with a change in CL cutoff = 1.6 mm/week or 4.1%/week the detection rate was 54.2% (32.8-74.4%) and the specificity 80.5% (75.1-85.1%) and 83.5% (78.5-87.8%) respectively. In the integrated strategy, the detection rate was 65.7% (47.8-80.9%) and the specificity 69 (63.7-74). All the ROC curves of the periods studied showed an AUC < 0.7. In the group of patients that delivered preterm the initial mean CL was shorter than in the term group, 39 (±12) mm vs. 43 (± 7.7) mm (p = .02) and the most important change in CL was at 20-24 weeks both in the velocity and in the ratio of shortening over time. Conversely, patients that delivered at term showed a higher change in CL in the third trimester.

CONCLUSION

The performance of all the strategies analyzed as a predictor of sPTB <34 weeks was moderate. The period 20-28 weeks detected half of the patients at risk with a FPR around 10-20% and the integrated strategy increased the sensitivity up to a detection of two thirds of the patients at risk but with a FPR of ∼30%. Future analyses need to explore other strategies to improve the performance and to really identify the patients at higher risk.

Is growth restriction in twin pregnancies a double challenge? - A narrative review

BACKGROUND

Foetal growth restriction (FGR) complicates about 25-47% of twin pregnancies. One or both foetuses can be restricted. Pregnancies with discordant growth of foetuses are associated with a sevenfold increased risk of neonatal morbidity.

MATERIALS AND METHODS

This is a narrative or traditional literature review. A literature search was performed to present a comprehensive, critical and objective analysis of the current knowledge on growth restriction in twin pregnancies.

RESULTS

The definitions of FGR in twin pregnancies and selective FGR (sFGR) differ between international societies. In 2019, the Delphi procedure aimed to unify the definitions of sFGR in twin pregnancies. Several growth charts for twins have been published. However, most societies recommend singleton growth charts as better in detecting hypoxic complications of FGR in twin pregnancies. Discordant growth in twins results from placental insufficiency, congenital anomalies, chromosomal aberrations and TORCH infections.

CONCLUSIONS

Definitions and management of sFGR depend on chorionicity. The management aims to protect the properly growing foetus from ischemic complications or in utero death. In most cases, expectant management, strict surveillance and preterm labour are the methods of choice. Due to the co-existence of properly growing and small foetuses in one uterus, determining the appropriate time for delivery is challenging. In the case of preterm labour, even late preterm, antenatal corticosteroid therapy (ACT) in FGR twin pregnancies is beneficial because it decreases neonatal morbidity.

Pregnancy and birth characteristics of Aboriginal twins in two Australian states: a data linkage study

INTRODUCTION

Perinatal outcomes for singleton pregnancies are poorer, on average, for Aboriginal people than non-Aboriginal people, but little is known about Aboriginal multifetal pregnancies. Yet multifetal pregnancies and births are often more complicated and have poorer outcomes than singleton pregnancies. We describe the pregnancies, births and perinatal outcomes for Aboriginal twins born in Western Australia (WA) and New South Wales (NSW) with comparisons to Aboriginal singletons in both states and to non-Aboriginal births in NSW.

MATERIALS AND METHODS

Whole-population birth records and birth and death registrations were linked for all births during 2000-2013 (WA) and 2002-2008 (NSW). Hospital records and the WA Register of Developmental Anomalies - Cerebral Palsy were linked for all WA births and hospital records for a subset of NSW births. Descriptive statistics are reported for maternal and child demographics, maternal health, pregnancy complications, births and perinatal outcomes.

RESULTS

Thirty-four thousand one hundred twenty-seven WA Aboriginal, 32,352 NSW Aboriginal and 601,233 NSW non-Aboriginal births were included. Pregnancy complications were more common among mothers of Aboriginal twins than Aboriginal singletons (e.g. 17% of mothers of WA twins had hypertension/pre-eclampsia/eclampsia vs 8% of mothers of singletons) but similar to mothers of NSW non-Aboriginal twins. Most Aboriginal twins were born in a principal referral, women's or large public hospital. The hospitals were often far from the mother's home (e.g. 31% of mothers of WA Aboriginal twins gave birth at hospitals located more than 3 h by road from their home). Outcomes were worse for Aboriginal liveborn twins than Aboriginal singletons and non-Aboriginal twins (e.g. 58% of NSW Aboriginal twins were preterm compared to 9% of Aboriginal singletons and 49% non-Aboriginal twins).

CONCLUSIONS

Mothers of Aboriginal twins faced significant challenges during the pregnancy, birth and the postnatal period in hospital and, in addition to accessible specialist medical care, these mothers may need extra practical and psychosocial support throughout their journey.

Prospective risk of stillbirth and neonatal complications for monochorionic diamniotic and dichorionic diamniotic twins after 24 weeks of gestation

INTRODUCTION

Our study compared the prospective risks of intrauterine fetal death (IUFD), neonatal death (NND), perinatal death (PND), and neonatal morbidities in monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies.

METHODS

This retrospective cohort study included twin pregnancies who had antenatal care and delivery in a public hospital from 2011 to 2018. Exclusion criteria included monoamnionicity, one/both twin miscarriage, twin-twin transfusion syndrome, or lethal congenital abnormalities. All twins were managed in multiple pregnancy clinic with standardized protocols. Gestational age-specific IUFD, NND, PND, and neonatal morbidity rates were compared according to chorionicity.

RESULTS

Three hundred seventy-eight MCDA and 1282 DCDA twins were included. MCDA twins had higher risks of PND (1.9% vs. 0.7% in DCDA twins, p = 0.05), composite neonatal morbidity (p = 0.01), preterm delivery (p < 0.01), and low birth weight (p < 0.01). The prospective risk of IUFD was 0.6% and 0.4% for MCDA and DCDA twins, respectively after 34 weeks' gestation. No NND occurred among deliveries after 30 weeks. The risk of neonatal morbidity of MCDA twins fell from 22.7% at 34 weeks to 2.7% at 37 weeks (p < 0.01). For DCDA twins, the risk of morbidity fell insignificantly from 36 to 38 weeks (4.0% vs. 3.4%, p = 0.60). Logistic regression analysis suggested that the increased risk of perinatal morbidities was related to the higher rate of preterm delivery in MCDA twins rather than chorionicity.

CONCLUSION

With close fetal monitoring, the risk of late IUFD in twin pregnancies without major complications is low. Perinatal morbidity can be minimized by avoiding late preterm deliveries in twin pregnancies.

Management of Twin Pregnancies: A Comparative Review of National and International Guidelines

Importance

Twin pregnancies are associated with a higher risk of perinatal mortality and morbidity compared with singleton and require more intensive prenatal care.

Objective

The aim of this study was to review and compare the recommendations from published guidelines on twin pregnancies.

Evidence Acquisition

A descriptive review of guidelines from the Royal College of Obstetricians and Gynaecologists, the International Society of Ultrasound in Obstetrics and Gynecology, the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, the National Institute for Health and Care Excellence, the Institute of Obstetricians and Gynaecologists of the Royal College of Physicians of Ireland, the International Federation of Gynecology and Obstetrics, the Society of Obstetricians and Gynaecologists of Canada, and the American College of Obstetricians and Gynecologists on the management of twin pregnancies was conducted.

Results

All the guidelines highlight the importance of an accurate assessment of chorionicity, amnionicity, and gestational age in the first trimester. They also recommend the performance of nuchal translucency and a detailed anomaly scan. The ultrasound surveillance protocol is similar in all guidelines, that is, every 2 weeks for monochorionic and every 4 weeks for dichorionic twins. On the other hand, there are differences regarding the timing and mode of delivery, especially in monochorionic diamniotic twins, in the definition and management of fetal growth discordance, the use of cervical length to screen for preterm birth, and the timing of corticosteroids' administration.

Conclusions

The differences in the reviewed guidelines on the management of twin pregnancies highlight the need for an adoption of an international consensus, in order to improve perinatal outcomes of twin pregnancies.

Monozygotic twins discordant for homologous Robertsonian translocation trisomy 21 of 46, XX, + 21, der (21;21) (q10; q10) in a twin-to-twin transfusion syndrome, case report

Background

Monozygotic twins are nearly identical in genotype and phenotype because monozygotic twins arise from one fertilized oocyte. In all cases of discordant karyotype in monozygotic twins, trisomy 21 accounts for about one in 385,000. Monozygotic twins discordant for Robertsonian translocation trisomy 21 of the der (21;21)(q10;q10), in which the additional chromosome originates from the father is rare.

Case presentation

A 28-year-old parous woman, G3P1A0, came to our institution for a dating scan at 8 weeks of gestation. The transvaginal ultrasound examination demonstrated a monochorionic diamniotic pregnancy. She and her husband were healthy, with no family history of trisomy 21 or other congenital diseases. The ultrasound examination of nuchal translucency thickness was discordant in twins at 13 weeks (twin A, NT 1.4 mm with CRL being 65 mm; twin B, NT 7.8 mm with CRL being 69 mm). At 17^+ 4 weeks, twin A was normal, but ventricular septal defect and the hypoplastic left heart was detected in twin B. The deepest vertical pocket was 18 mm in twin A (oligohydramnios) and 102 mm in Twin B (polyhydramnios). The bladder in twin A was absent. Ultrasound findings indicated TTTS Stage II. Amniocentesis was performed for the two fetuses. The karyotyping results revealed 46, XX in twin A but 46,XX,+ 21,der (21;21)(q10;q10) in twin B.

For twin B, the parents opted for selective fetal termination by radiofrequency ablation. The procedure was uneventful. At 40^+ 5 weeks, twin A was born with a birth weight of 4120 g by vaginal delivery.

Conclusions

The early detection of discordant karyotype and twin-to-twin transfusion syndrome is beneficial to the early intervention. In monozygotic twins with a discordant anomaly, the discordant karyotype should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03587-x.

Cervical-length as a screening for spontaneous preterm birth in uncomplicated twins: one vs. serial measurements

OBJECTIVE

While cervical length (CL) provides an effective screening tool for spontaneous preterm birth in singletons, the performance in twins is still controversial. Our aim was twofold. First, to compare the performance of a single CL measurement at mid-gestation (∼20 weeks) versus serial measurements as a predictor of spontaneous preterm birth < 34 weeks in uncomplicated twin pregnancies. Second, to describe the performance of a single CL at ∼24, ∼28 and ∼32 weeks.

MATERIAL AND METHODS

cohort study of twins followed at Hospital Italiano de Buenos Aires from 2013 to 2017. Inclusion criteria were dichorionic or monochorionic diamniotic twins with CL measurement between 18 and 33 + 6 weeks with available data of the delivery. Exclusion criteria included any of the following complications: iatrogenic preterm delivery <34 weeks, cerclage, fetal growth restriction, fetal death, structural anomalies, polyhydramnios, twin-twin transfusion syndrome, selective fetal growth restriction, twin anemia-polycythemia sequence, and twin reversed arterial perfusion sequence. Spontaneous preterm birth was defined as spontaneous delivery < 34 weeks. Two different cutoffs were used to classify CL as short (positive screening) or normal (negative screening): (a) a fixed cutoff of 25 mm at any gestational age (GA). The screening was considered positive if any CL measurement was <25 mm; and (b) a GA adjusted cutoff to a 10% false positive rate (FPR). The 10% FPR for each GA was calculated and the screening was considered positive if any of the CL measurements were below this 10% FPR cutoff. We report sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratio and area under the ROC curve.

RESULTS

Among 777 twins followed in our Unit, 381 met exclusion criteria and 18 were excluded due to incomplete follow-up. We included 378 patients, 284 (75%) dichorionic and 94 (25%) monochorionic. The performance of one CL at 20 weeks showed a sensitivity ≤ 20% with an area under the ROC curve of 0.58 (95% CI, 0.45-0.70), while the performance of serial measurements showed a sensitivity of 58.8% (95% CI, 40.7-75.4) with an area under the ROC curve of 0.70 (95% CI, 0.61-0.79) (p < .001). The analyses of the performance of a single CL at ∼24, ∼28 and ∼32 weeks showed similar AUC than the serial measurements and, for a FPR = 10%, the performance of one measurement at 24 and 32 weeks showed a sensitivity of 30% (95% CI, 14.7-49.4) and 31.6% (95% CI, (12.6-56.6), while the measurement at 28 weeks showed a sensitivity of 48.3% (95% CI, (29.4-67.5).

CONCLUSION

Serial measurements showed a better performance than a single one in mid-gestation. Moreover, among single measurements the CL in mid-gestation showed the poorest performance, while the 28 weeks assessment detected half of the preterm deliveries. However, all the strategies showed modest performances.

Current Practice of Maternal-Fetal Medicine Specialists Regarding the Prevention and Management of Preterm Birth in Twin Gestations

OBJECTIVE

To investigate the current practices of maternal-fetal medicine (MFM) specialists regarding the prevention and management of preterm birth (PTB) in twin pregnancies.

METHODS

This was a cross-sectional study of Canadian MFM specialists. Participants responded to an anonymous survey regarding the prevention and management of PTB in twins, including lifestyle and gestational weight gain recommendations, cervical length screening, PTB prevention, and labour and delivery practices.

RESULTS

Of 137 MFM specialists surveyed, 95 (69%) responded. Most MFM specialists recommend against activity restriction (77.9%), avoidance of sexual activity (96.7%), routine progesterone (97.8%), routine prophylactic cerclage (98.9%), and routine administration of antenatal corticosteroids (95.6%). There were considerable inconsistencies with respect to gestational weight gain management. Despite lack of support by guidelines, most MFM specialists reported using routine cervical length screening (97.8%) and progesterone for short cervix (92.3%). Over half (52.7%) of MFM specialists recommend cervical cerclage when the cervix is <15mm. In cases of PTB, most MFM specialists recommend vaginal delivery when twins are in vertex presentation (63%-75%). MFM specialists are less likely to recommend vaginal delivery when twin B is non-vertex (35%-41%).

CONCLUSION

There is a considerable variation among MFM specialists regarding the prevention and management of PTB in twins, and the practice of many MFM specialists differs from that recommended by professional societies' guidelines. These findings underscore the necessity for high-quality studies and up-to-date recommendations.