Increased perinatal mortality and morbidity in monochorionic versus dichorionic twin pregnancies: clinical implications of a large Dutch cohort study

Mode of delivery in multiple pregnancies

The mode of delivery in multiple pregnancies has been subject to vigorous debates during the last few decades. Although observational and retrospective data were accumulated, it was not until the publication of the Twin Birth Study that evidence-based recommendations could emerge. However, although some of the most pressing questions were answered by the Twin Birth Study, other questions were left outside the scope of the study. The questions were of great interest and included the following topics: the impact of gestational age, the influence of chorionicity, and the generalizability of the results for women with a previous uterine scar. The current evidence supported a trial of labor in dichorionic-diamniotic or monochorionic-diamniotic twin pregnancies in which the first twin is in cephalic presentation at ≥32 weeks' gestation. Dichorionic-diamniotic, monochorionic-diamniotic, and monochorionic-monoamniotic twins should be delivered at 37 0/7 to 38 0/7, 36 0/7 to 37 0/7, and 32 0/7 to 34 0/7 weeks' gestation, respectively. Breech extraction done by a competent healthcare provider seemed to offer a higher chance of successful vaginal delivery of the second twin than the external cephalic version. The current data did not allow for a clear recommendation regarding the mode of delivery in very preterm birth of low birthweight twins, but most studies did not demonstrate a clear benefit of cesarean delivery vs trial of labor. Furthermore, a trial of labor seemed safe in women with a previous cesarean delivery. Cesarean delivery is likely beneficial for twin pregnancies with the first twin in breech presentation, monochorionic-monoamniotic twins, and higher-order multiple pregnancies. In all multiple pregnancies, delivery should be performed by an experienced practitioner competent in multiple pregnancy deliveries.

Maternal, Fetal, and Neonatal Outcomes of Elective Fetal Reduction Among Multiple Gestation Pregnancies: A Systematic Review

OBJECTIVE

To review the existing literature on fetal and maternal health outcomes following elective pregnancy reduction.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, the Cochrane Database of Systematic Reviews, and the Cochrane Controlled Trials Register.

STUDY SELECTION

Studies involving women pregnant with dichorionic twins, trichorionic triplets, or quadra-chorionic quadruplets who underwent elective fetal reduction of 1 or more fetuses to reduce the risks associated with multiple gestation pregnancies.

DATA EXTRACTION

The main fetal health outcomes measured were gestational age at delivery, preterm birth, miscarriage, birthweight, and small for gestational age at delivery. The main maternal health outcomes measured were gestational diabetes, hypertensive disorders of pregnancy, and cesarean delivery.

DATA SYNTHESIS

Of 7678 studies identified, 24 were included (n = 425 dichorionic twin pregnancies, n = 2753 trichorionic triplet pregnancies, and n = 111 quadra-chorionic quadruplet pregnancies). Fifteen studies (62.5%) did not report maternal health outcomes, while every study reported at least 1 fetal health outcome. Fetal reduction was associated with higher gestational age at birth, lower preterm birth, higher birthweight, and lower rates of small for gestational age infants and intrauterine growth restriction. No consistent pattern was observed for miscarriage and neonatal mortality rates. Following fetal reduction, cesarean delivery rates were lower in most studies. There were no appreciable trends with respect to gestational diabetes or hypertensive disorders of pregnancy.

CONCLUSION

Fetal reduction reliably optimizes gestational age at birth and neonatal birthweight. Miscarriage rates and other adverse procedural outcomes did not increase following transabdominal reduction. Further research on maternal outcomes is needed given a paucity of information in the literature.

Mode of Delivery in Monochorionic Compared With Dichorionic Twin Pregnancies

OBJECTIVE

To compare mode of delivery between monochorionic and dichorionic twin pregnancies.

METHODS

This was a retrospective cohort study of women undergoing delivery of diamniotic twins in a single maternal-fetal medicine practice in New York City between 2005 and 2021. We compared baseline characteristics and delivery outcomes between monochorionic and dichorionic gestations. The primary outcome was mode of delivery. For monochorionic-diamniotic twin pregnancies at or after 34 weeks of gestation, we also compared neonatal outcomes between women who did and did not attempt vaginal delivery. Data were analyzed using the χ2 test, Fisher exact test, and t test when appropriate.

RESULTS

A total of 1,121 diamniotic twin pregnancies were identified, of which 202 (18%) were monochorionic and 919 (82%) were dichorionic. Mode of delivery did not differ between monochorionic and dichorionic pregnancies, both in the overall cohort (cesarean delivery rate 61% vs 63%, P=.54) and in the subgroup of women who attempted vaginal delivery (cesarean delivery rate 22% vs 21%, P=.80). For patients with a vaginal delivery of twin A, the mode of delivery for twin B did not differ between the groups. Among the patients with monochorionic pregnancies at or after 34 weeks of gestation, neonatal outcomes did not differ between women who did and did not attempt vaginal delivery.

CONCLUSION

Monochorionic-diamniotic pregnancies are not at an increased risk of cesarean delivery when compared with their dichorionic-diamniotic counterparts.

Multifetal Gestations: Twin, Triplet, and Higher-Order Multifetal Pregnancies: ACOG Practice Bulletin, Number 231

The incidence of multifetal gestations in the United States has increased dramatically over the past several decades. For example, the rate of twin births increased 76% between 1980 and 2009, from 18.9 to 33.3 per 1,000 births (1). However, after more than three decades of increases, the twin birth rate declined 4% during 2014-2018 to 32.6 twins per 1,000 total births in 2018 (2). The rate of triplet and higher-order multifetal gestations increased more than 400% during the 1980s and 1990s, peaking at 193.5 per 100,000 births in 1998, followed by a modest decrease to 153.4 per 100,000 births by 2009 (3). The triplet and higher-order multiple birth rate was 93.0 per 100,000 births for 2018, an 8% decline from 2017 (101.6) and a 52% decline from the 1998 peak (193.5) (4). The long-term changes in the incidence of multifetal gestations has been attributed to two main factors: 1) a shift toward an older maternal age at conception, when multifetal gestations are more likely to occur naturally, and 2) an increased use of assisted reproductive technology (ART), which is more likely to result in a multifetal gestation (5). A number of perinatal complications are increased with multiple gestations, including fetal anomalies, preeclampsia, and gestational diabetes. One of the most consequential complications encountered with multifetal gestations is preterm birth and the resultant infant morbidity and mortality. Although multiple interventions have been evaluated in the hope of prolonging these gestations and improving outcomes, none has had a substantial effect. The purpose of this document is to review the issues and complications associated with twin, triplet, and higher-order multifetal gestations and present an evidence-based approach to management.

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.

Controversies in the management of twin pregnancy

Despite many advances in antenatal care, twin pregnancies still experience more adverse outcomes, in particular perinatal morbidity and mortality. They also pose a multitude of challenges and controversies, as outlined in this Review. Moreover, they are less likely to be included in clinical trials. Many issues on classification and management remain under debate. Efforts at standardizing diagnostic criteria, monitoring protocols, management and outcome reporting are likely to reduce their perinatal risks. The top 10 most important research uncertainties related to multiple pregnancies have been identified by both clinicians and patients. More robust research in the form of randomized trials and large well-conducted prospective cohort studies is needed to address these controversies. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Gestational Weight Gain in Twin Pregnancies and Maternal and Child Health: An Updated Systematic Review

Background: The Institute of Medicine (IOM) has provisional gestational weight gain (GWG) guidelines for women pregnant with twins due to limited data in this population. To better inform guidelines, the objective of this systematic review was to build on prior work and examine recent data on the associations of GWG with maternal and child health in twin pregnancies. Materials and Methods: In February 2021, Ovid MEDLINE, Embase, CINAHL, and Cochrane Library were searched. Observational studies were eligible if published from January 1, 2013 through February 23, 2021, and examined associations of GWG with maternal or child health outcomes after accounting for gestational age at delivery and pre-pregnancy body mass index. Heterogeneity across studies precluded the use of meta-analytic methods. Results: A total of 29 studies were included. For maternal outcomes, excessive GWG was associated with an increased risk of hypertensive disorders of pregnancy; whereas studies examining gestational diabetes and delivery method reported mixed findings. For child outcomes, inadequate GWG was associated with lower birthweight, small for gestational age, and preterm birth. Adequate or excessive GWG was associated with later gestational age at delivery. Conclusions: This study advances an earlier review by including a more diverse array of maternal and child outcomes. Many of the limitations noted in the original review persist; for example, no studies examined the associations of GWG and outcomes beyond birth. Although it appears that GWG within the IOM guidelines is associated with more optimal outcomes, additional methodologically rigorous studies are needed to better inform evidence-based guidelines.

Perinatal outcome after planned vaginal delivery in monochorionic compared with dichorionic twin pregnancy

OBJECTIVE

To assess, according to chorionicity, the perinatal outcome of twin pregnancy in which vaginal delivery is planned.

METHODS

JUMODA (JUmeaux MODe d'Accouchement) was a national prospective population-based cohort study of twin pregnancies, delivered in 176 maternity units in France, from February 2014 to March 2015. In this planned secondary analysis, we assessed, according to chorionicity, the perinatal outcome of twin pregnancies, in which vaginal delivery was planned, that delivered at or after 32 weeks of gestation with the first twin in cephalic presentation. In order to select a population with well-recognized indications for planned vaginal delivery, we applied the same exclusion criteria as those in the Twin Birth Study, an international randomized trial. Monochorionic twin pregnancies with twin-to-twin transfusion syndrome or twin anemia-polycythemia sequence were defined as complicated and were excluded. The primary outcome was a composite of intrapartum mortality and neonatal morbidity and mortality. Multivariable logistic regression models were used to control for potential confounders. Subgroup analyses were conducted according to birth order (first or second twin) and gestational age at delivery (< 37 or ≥ 37 weeks of gestation).

RESULTS

Among 3873 twin pregnancies, in which vaginal delivery was planned, that delivered at ≥ 32 weeks' gestation with the first twin in cephalic presentation, meeting the inclusion criteria of the Twin Birth Study, 729 (18.8%) were uncomplicated monochorionic twin pregnancies and 3144 (81.2%) were dichorionic twin pregnancies. The rate of composite intrapartum mortality and neonatal morbidity and mortality did not differ between uncomplicated monochorionic (27/1458 (1.9%)) and dichorionic (107/6288 (1.7%)) twin pregnancies when adjusting for conception by assisted reproductive technologies (adjusted relative risk, 1.07 (95% CI, 0.66-1.75)). No significant difference in the primary outcome was found between the groups on subgroup analyses according to birth order and gestational age at delivery.

CONCLUSION

When vaginal delivery is planned, and delivery occurs at ≥ 32 weeks of gestation with the first twin in cephalic presentation, uncomplicated monochorionic twin pregnancy is not associated with a higher rate of composite intrapartum mortality and neonatal morbidity and mortality compared with dichorionic twin pregnancy. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Mathematical Analysis of EEG Concordance in Preterm Twin Infants

PURPOSE

Preterm twins are at higher risk of neurodisability than preterm singletons, with monochorionic-diamniotic (MCDA) twins at higher risk than dichorionic-diamniotic (DCDA) twins. The impact of genetic influences on EEG concordance in preterm twins <32 weeks of gestational age is not established. This study aims to investigate EEG concordance in preterm MCDA and dichorionic-diamniotic twins during maturation.

METHODS

Infants <32 weeks of gestational age had multichannel EEG recordings for up to 72 postnatal hours, with repeat recordings at 32 and 35 weeks of postmenstrual age. Twin pairs had synchronous recordings. Mathematical EEG features were generated to represent EEG power, discontinuity, and symmetry. Intraclass correlations, while controlling for gestational age, estimated similarities within twins.

RESULTS

EEGs from 10 twin pairs, 4 MCDA and 6 dichorionic-diamniotic pairs, and 10 age-matched singleton pairs were analyzed from a total of 36 preterm infants. For MCDA twins, 17 of 22 mathematical EEG features had significant (>0.6; P < 0.05) intraclass correlations at one or more time points, compared with 2 of 22 features for DCDA twins and 0 of 22 for singleton pairs. For MCDA twins, all 10 features of discontinuity and all four features of symmetry were significant at one or more time-points. Three features of the MCDA twins (spectral power at 3-8 Hz, EEG skewness at 3-15 Hz, and kurtosis at 3-15 Hz) had significant intraclass correlations over all three time points.

CONCLUSIONS

Preterm twin EEG similarities are subtle but clearly evident through mathematical analysis. MCDA twins showed stronger EEG concordance across different postmenstrual ages, thus confirming a strong genetic influence on preterm EEG activity at this early development stage.

Delivery of monochorionic twins: lessons learned from the Twin Birth Study

BACKGROUND

The current literature regarding the recommended mode of delivery of monochorionic-diamniotic twins is limited to small numbers, retrospective studies, and comparisons of outcomes of monochorionic-diamniotic twin pregnancies with those of dichorionic-diamniotic twin pregnancies instead of outcomes of trial of labor vs elective cesarean delivery of monochorionic-diamniotic twins.

OBJECTIVE

This study aimed to compare perinatal and maternal outcomes of planned cesarean delivery and planned vaginal delivery of monochorionic-diamniotic twins using the Twin Birth Study data.

STUDY DESIGN

This study is a secondary analysis of the Twin Birth Study. Women were randomized from 32 weeks and 0 days gestation to 38 weeks and 6 days gestation to planned cesarean delivery or planned vaginal delivery. Twin A in the cephalic presentation and estimated weight of each twin between 1500 and 4000 grams were the inclusion criteria. Pregnancies complicated by fetal reduction after 13 weeks of gestation, lethal fetal anomaly, or contraindication to vaginal delivery were excluded. Elective delivery was planned between 37 weeks and 5 to 7 days of gestation and 38 weeks and 6 to 7 days of gestation. Perinatal and maternal outcomes of monochorionic-diamniotic twin pregnancies were compared between those randomized for planned cesarean delivery and those randomized for planned vaginal delivery. In addition, outcomes of monochorionic-diamniotic twin pregnancies were compared with those of dichorionic-diamniotic twin pregnancies.

RESULTS

Out of the 1393 women in each arm, 346 (24.9%) women in the planned cesarean delivery arm and 324 (23.3%) women in the planned vaginal delivery arm had monochorionic-diamniotic twin pregnancies and were eligible for the first analysis. The rate of cesarean delivery was 39.2% in the planned vaginal delivery arm and was 91.3% in the planned cesarean delivery arm. There was no significant difference in gestational age at delivery between the groups (34.4±1.8 weeks vs 34.5±1.8 weeks; P=.78). No difference was found in maternal outcomes. As for perinatal outcomes, the rate of the primary adverse neonatal composite outcomes in twins A or twins B was similar in both the planned vaginal delivery and the planned cesarean delivery arms (twins A, 1.2% vs 1.2% [P=.92]; twins B, 1.2% vs 3.2% [P=.09]). Within the planned cesarean delivery arm, the rate of primary adverse neonatal composite outcome was higher in twins B than twins A (3.2% vs 1.2%; P=.03). There was no difference in the primary adverse neonatal composite outcome between twins A in the monochorionic-diamniotic group and the dichorionic-diamniotic group (1.2% vs 1.3%; P=.89) or between twins B in similar groups (2.3% vs 2.7%; P=.47).

CONCLUSION

In monochorionic-diamniotic twin pregnancy between 32 weeks and 0 to 7 days of gestation and 38 weeks and 6 to 7 days of gestation, with twin A in a cephalic presentation, planned cesarean delivery did not decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery.

Retrospective evaluation of attempted vaginal deliveries in dichorionic twin pregnancies

Purpose

Numbers of planned cesarean deliveries are increasing in twin pregnancies, despite the lack of evidence for this approach, and the second twin is thought to be at risk for a poorer outcome. The aim of this study was to examine whether twins have a poorer outcome if an attempted vaginal delivery is changed to a cesarean section or combined delivery.

Methods

This retrospective data analysis included all women with dichorionic twin pregnancies attempting vaginal delivery over a 10-year period. Outcome parameters for the first and second twins relative to their mode of birth were compared. A correlation model between the interdelivery time interval and Apgar scores was calculated. Subgroup analyses assessing the birth mode of the first and second twins were conducted.

Results

A total of 248 women were enrolled in the study. The second twins had significantly lower values for outcome parameters, such as umbilical artery cord pH and Apgar scores in comparison with the first twins (P < 0.01). The subgroup analysis of birth modes in first and second twins showed a significantly poorer outcome in the cesarean section and combined delivery group (P < 0.05). The interdelivery time interval was significantly longer in the second twin cesarean section group (P < 0.01). There was no significant correlation between the interdelivery time intervals and Apgar scores (P > 0.05).

Conclusion

Although outcome parameters were significantly lower in second twins and twins born via secondary cesarean section, the clinical relevance of this appears to be negligible.

Prenatal and perinatal outcomes of twin pregnancy discordant for one fetus with nuchal translucency above the 95th percentile

OBJECTIVE

To compare prenatal and perinatal outcomes of twin pregnancies in which one twin the nuchal translucency (NT) was above the 95th percentile in dichorionic twins (DCT) and monochorionic twins (MCT).

METHOD

In this retrospective study, 93 twin pregnancies (186 fetuses) in which one twin the NT was above the 95th percentile and the co-twin had normal NT were analyzed. Results of of G-banding and Chromosomal microarray (CMA), ultrasound findings and pregnancy outcomes were reviewed.

RESULTS

Totally, 57 pregnancies (114 fetuses) were DCT and 36 pregnancies (72 fetuses) were MCT. Karyotyping and CMA results shown that clinically significant chromosomal abnormalities were found in 16 fetuses, including 13 aneuploidies, 2 chromosomal mosaic and 1 pathological Copy number variations (CNVs) (14 were DCT and 2 were MCT). Overall, the incidence of fetal chromosomal abnormalities was 12.3% (14/114) in DCT and 2.8%(2/72) in MCT (χ² = 3.932, p = 0.047). Among the cases with normal prenatal diagnosis result, structural abnormalities were found in four fetuses (4.0%, 4/100) in DCT and two fetuses (2.9%, 2/70) in MCT (p > 0.999). There were one intrauterine fetal demises (IUFD) and two miscarry in DCT. One IUFD, three subsequently developed Twin-to-Twin Transfusion Syndrome (TTTS) and four developed selective intrauterine growth restriction (sIUGR) in MCT. Totally, the overall fetal survival rate was 85.1% (97/114) in DCT and 80.6% (58/72) in MCT (χ² = 0.653, p = 0.419).

CONCLUSION

Compared to MCT, the incidence of chromosomal abnormalities in DCT discordant for one fetus with NT above the 95th percentile was higher. The risk of structural abnormalities and the rate of fetal survival for both MCT and DCT was similar.

Both Low and High PAPP-A Concentrations in the First Trimester of Pregnancy Are Associated with Increased Risk of Delivery before 32 Weeks in Twin Gestation

In twin gestation, the relationship between pregnancy associated plasma protein (PAPP-A) and perinatal outcome is unclear. The aim of the study was to determine if low and high concentrations of PAPP-A in the first trimester are related to perinatal outcome in twins. A retrospective study was conducted. Medical data of women in twin pregnancies who delivered between 2013 and 2018 were analyzed. PAPP-A concentrations were measured between 10 + 0 and 13 + 6 weeks. The associations between low (<10th percentile) and high (>90th percentile) values of PAPP-A and pregnancy complications were analyzed. A total of 304 patients were included. PAPP-A <10th percentile was associated with a high risk of preterm delivery (OR 6.14; 95% CI 2.1-18), delivery <34 weeks (OR 2.39; 95% CI 1.1-5.1) or <32 weeks (OR3.06; 95% CI 1.4-6.8). Significant relations between PAPP-A >90th percentile and delivery <34 weeks (OR4.09; 95% CI 1.8-9.1) or <32 weeks (OR 2.83; 95% CI 1.2-6.6) were found. PAPP-A >90th percentile was related to high risk of intrauterine fetal demise (OR 10; 95% CI 2.4-42.5). Both low and high PAPP-A concentrations seem to be related to pregnancy outcome. Further research is needed to investigate evaluation of risk of pregnancy complications according to PAPP-A concentrations as a continuous variable.

Double trouble? Clinic-specific risk factors for monozygotic twinning

OBJECTIVE

To investigate clinic-specific risk factors for monozygotic twinning (MZT) using a large, electronic database.

DESIGN

Retrospective case-control study.

SETTING

Infertility clinics.

PATIENT(S)

Using an electronic medical record system, viable clinical pregnancy (confirmation of a gestational sac(s) and presence of at least one fetal pole with a heartbeat on first trimester ultrasound), data were obtained from homologous in vitro fertilization (IVF) cycles after single ET from June 1, 2004, to December 31, 2016. Monozygotic twinning was defined as a pregnancy with two fetal heartbeats on ultrasound with sex concordance at birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Risk factors for MZT including cycle type, method of insemination, and method of cryopreservation.

RESULT(S)

Of the 28,265 IVF cycles that met inclusion criteria over the study period, 8,749 (31.0%) resulted in a viable intrauterine clinical pregnancy. There were 102 (2.7%) MZT in the fresh cycle cohort and 133 (2.7%) in the frozen cycle cohort. Neither cryopreservation nor the method of cryopreservation was a significant risk factor for MZT. However, the use of sequential media was an independent risk factor for MZT in fresh, but not frozen, ETs (odds ratio = 1.72, 95% confidence interval, 1.10-2.68). Significant differences were seen in the incidence of MZT between clinics, and this difference persisted after controlling for known risk factors (clinic 0, reference; clinic 2, odds ratio = 2.22; 95% confidence interval, 1.48-3.32; clinic 3, odds ratio = 1.93; 95% confidence interval, 1.30-2.87).

CONCLUSION(S)

Differences in MZT rates exist between individual IVF clinics, suggesting that variations in practice patterns may contribute to this event. The present study noted the use of sequential media was an independent risk factor for fresh but not frozen cycles.

Neonatal hair profiling reveals a metabolic phenotype of monochorionic twins with selective intrauterine growth restriction and abnormal umbilical artery flow

BACKGROUND

Selective intrauterine fetal growth restriction (sIUGR) in monochorionic diamniotic twins, especially types 2&3 with abnormal umbilical artery Doppler, results in increased risk of fetal/perinatal mortality and postnatal disability. We investigate whether the hair metabolome profiles of neonates were associated with the pathophysiological differences across the different clinical forms of sIUGR in twins.

METHODS

Hair samples were collected at delivery from 10 pairs of type 1 sIUGR twins, 8 pairs of types 2&3 sIUGR twins, and 11 pairs of twins without sIUGR. The hair metabolome was characterized using gas chromatography-mass spectrometry.

RESULTS

Our results demonstrated that the hair metabolite profiles of the different sIUGR subclinical forms were associated with the averaged fetal growth rate after 28 weeks of gestation but not with birthweight. The hair profiles were capable of discriminating type2&3 sIUGR twins from twins without sIUGR. In particular, the metabolites 2-aminobutyric acid, cysteine, alanine, and tyrosine all displayed areas under the receiver operating characteristic curve were above 0.9. The metabolic pathway analysis highlighted the associations of sIUGR twins with abnormal umbilical artery flow with increased metabolites from a nutrient depletion pathway, glutathione metabolism, and nerve development.

CONCLUSION

This study offers novel insight into the severity of intrauterine ischemia and hypoxia for T2&3 sIUGR twins, through evaluation of the neonatal hair metabolome.

Cerebral oxygenation reflects fetal development in preterm monochorionic and dichorionic twins

BACKGROUND

Cerebral oxygenation (crSO₂) monitoring is increasingly used in high-risk infants. Monochorionic twins suffer from specific fetal pathologies that can affect cerebral hemodynamics. Limited data are available on crSO₂ and blood flow patterns in this population after birth.

OBJECTIVE

To evaluate crSO₂ changes in preterm monochorionic and dichorionic twins during the first 72 h of life.

METHODS

Near-infrared spectroscopy was used to measure crSO₂ in 62 infants from 31 twin pregnancies <32 weeks of gestation. The study group was divided into 4 subgroups: donor (1) and recipient (2) monochorionic twins (with twin-twin transfusion syndrome), fetal growth restriction (FGR) infants (3) and twins without fetal compromise (4).

RESULTS

There was significant difference in birth weight (p < 0.001) among 4 subgroups. We observed significant variation in crSO₂ among the subgroups using mixed model analysis (p < 0.001). The recipient twins exhibited the lowest crSO₂ (mean ± SE) throughout the study period (76 ± 0.3%), whereas the FGR and donor twins presented with the highest values (86 ± 0.3% and 83 ± 0.4% respectively). We found no statistically significant differences in neonatal mortality and morbidity among subgroups.

CONCLUSION

Our study revealed significant correlation between crSO₂ values postnatally and underlying fetal pathology in monochorionic and dichorionic preterm twins.

Effect of Chorionicity on Umbilical Cord Blood Acid-Base Analysis of the Second Twin

Our objective was to determine whether chorionicity affects umbilical cord blood acid-base parameters of the second twin. This was a retrospective cohort of twin pregnancies delivered at ≥23 weeks of gestation at a tertiary hospital from 2010 to 2016. Patients were included if arterial and venous umbilical cord gas results were available for both newborns and chorionicity was confirmed histologically. Exclusion criteria included intrauterine fetal demise of either twin prior to labor, major fetal anomalies, monoamnionicity, uncertain chronicity and twin-to-twin transfusion syndrome. The primary outcome evaluated was the umbilical artery (UA) pH of the second twin. A total of 593 dichorionic (DC) and 86 monochorionic (MC) twin pregnancies were included. No difference in UA pH was observed between MC and DC twins. Among vaginal deliveries (n = 97), the UA pH of the first twin was higher than the second twin (7.26 vs. 7.24; p = .01). Twin-to-twin delivery interval (TTDI) ≥20 min was associated with a higher UA pH in the first twin compared to the second twin (7.25 vs. 7.16, respectively; p = .006). Multivariable logistic regression was used to predict arterial pH < 7.20 for the second twin; the most predictive factors were arterial pH < 7.20 for the first twin, chronic hypertension and prolonged TTDI. Chorionicity was not associated with any acid-base parameter of umbilical cord blood in either the first or second twin. No differences in neonatal outcomes were observed based on chorionicity or birth order. Populations with a lower cesarean delivery rate may yield different findings.

The impact of chorionicity on pregnancy outcome and neurodevelopment at 2 years old among twins born preterm: the EPIPAGE-2 cohort study

OBJECTIVE

To compare the short- and mid-term outcomes of preterm twins by chorionicity of pregnancy.

DESIGN

Prospective nationwide population-based EPIPAGE-2 cohort study.

SETTING

546 maternity units in France, between March and December 2011.

POPULATION

A total of 1700 twin neonates born between 24 and 34 weeks of gestation.

METHODS

The association of chorionicity with outcomes was analysed using multivariate regression models.

MAIN OUTCOME MEASURES

First, survival at 2-year corrected age with or without neurosensory impairment, and second, perinatal, short-, and mid-term outcomes (survival at discharge, survival at discharge without severe morbidity) were described and compared by chorionicity.

RESULTS

In the EPIPAGE 2 cohort, 1700 preterm births were included (850 twin pregnancies). In all, 1220 (71.8%) were from dichorionic (DC) pregnancies and 480 from monochorionic (MC) pregnancies. MC pregnancies had three times more medical terminations than DC pregnancies (1.67 versus 0.51%, P < 0.001), whereas there were three times more stillbirths in MC than in DC pregnancies (10.09 versus 3.78%, P < 0.001). Both twins were alive at birth in 86.6% of DC pregnancies compared with 80.0% among MC pregnancies (P = 0.008). No significant difference according to chorionicity was found regarding neonatal deaths and morbidities. Likewise, for children born earlier than 32 weeks, the 2-year follow-up neurodevelopmental results were not significantly different between DC and MC twins.

CONCLUSIONS

This study confirms that MC pregnancies have a higher risk of adverse outcomes. However, the outcomes among preterm twins admitted to neonatal intensive care units are similar irrespective of chorionicity.

TWEETABLE ABSTRACT

Monochorionicity is associated with adverse perinatal outcomes, but outcomes for preterm twins are comparable irrespective of their chorionicity.

The Canadian Assisted Reproductive Technologies Register (CARTR) Plus database: a validation study

STUDY QUESTION

Are data accurately documented in the Canadian Assisted Reproductive Technologies Register (CARTR) Plus database?

SUMMARY ANSWER

Measures of validity were strong for the majority of variables evaluated while those with moderate agreement were FSH levels, oocyte origin and elective single embryo transfer.

WHAT IS KNOWN ALREADY

Health databases and registries are excellent sources of data. However, as these databases are typically not established for the primary purpose of performing research, they should be evaluated prior to utilization for research both to inform the study design and to determine the extent to which key study variables, such as patient characteristics or therapies provided, are accurately documented in the database. CARTR Plus is Canada's national register for collecting extensive information on IVF and corresponding pregnancy outcomes, and it has yet to be validated.

STUDY DESIGN SIZE DURATION

This study evaluating the data translation CARTR Plus database examined IVF cycles performed in 2015 using data directly from patient charts. Six clinics across Canada were recruited to participate, using a purposive sampling strategy. Fixed random sampling was employed to select 146 patient cycles at each clinic, representing unique patients. Only a single treatment cycle record from a unique patient at each clinic was considered during chart selection.

PARTICIPANTS/MATERIALS SETTING METHODS

Twenty-five data elements (patient characteristics, treatments and outcomes) were reabstracted from patient charts, which were declared the reference standard. Data were reabstracted by two independent auditors with relevant clinical knowledge after confirming inter-rater reliability. These data elements from the chart were then compared to those in CARTR Plus. To determine the validity of these variables, we calculated kappa coefficients, sensitivity, specificity, positive predictive value and negative predictive value with 95% CI for categorical variables and calculated median differences and intraclass correlation coefficients (ICC) for continuous variables.

MAIN RESULTS AND THE ROLE OF CHANCE

Six clinics agreed to participate in this study representing five Canadian provinces. The mean age of patients was 35.5 years, which was similar between the two data sources, resulting in a near perfect level of agreement (ICC = 0.99; 95% CI: 0.99, 0.99). The agreement for FSH was moderate, ICC = 0.68 (95% CI: 0.64, 0.72). There was nearly perfect agreement for cycle type, kappa = 0.99 (95% CI: 0.98, 1.00). Over 90% of the cycles in the reabstracted charts used autologous oocytes; however, data on oocyte source were missing for 13% of cycles in CARTR Plus, resulting in a moderate degree of agreement, kappa = 0.45 (95% CI, 0.37, 0.52). Embryo transfer and number of embryos transferred had nearly perfect agreement, with kappa coefficients greater than 0.90, whereas that for elective single or double embryo transfer was much lower (kappa = 0.55; 95% CI: 0.49, 0.61). Agreement was nearly perfect for pregnancy type, and number of fetal sacs and fetal hearts on ultrasound, all with kappa coefficients greater than 0.90.

LARGE-SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

CARTR Plus contains over 200 variables, of which only 25 were assessed in this study. This foundational validation work should be extended to other CARTR Plus database variables in future studies.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides the first assessment of the quality of the data translation process of the CARTR Plus database, and we found very high quality for the majority of the variables that were analyzed. We identified key data points that are either too often lacking or inconsistent with chart data, indicating that changes in the data entry process may be required.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by Canadian Institutes of Health Research (CIHR) (Grant Number FDN-148438) and by the Canadian Fertility and Andrology Society Research Seed Grant (Grant Number: N/A). The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

Not applicable.

Impact of first trimester determination of abnormal cord insertion on twin-to-twin transfusion syndrome and other adverse outcomes in monochorionic diamniotic twins: A retrospective cohort study

OBJECTIVE

To assess the influence of abnormal cord insertion (CI) detected by first trimester ultrasonography on the development of twin-to-twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) twins.

METHOD

In this retrospective cohort study, consecutive patients with MCDA twins who underwent fetal ultrasound screening in the first trimester between January 2011 and January 2017 were enrolled. The CI sites were evaluated between 11 + 0 and 13 + 6 weeks' gestation. All twin pairs were assigned to the abnormal CI group (twin pair with velamentous cord insertion (VCI) and/or marginal cord insertion (MCI) in one or both twins) or the normal CI group (twin pair with both normal CI). The relationships of adverse outcomes in two groups were analyzed.

RESULTS

A total of 109 MCDA twin pairs were examined; 15 cases were classified into the abnormal CI group and 94 cases into the normal CI group. The incidence of TTTS was significantly higher in the abnormal than in the normal CI group (26.7% vs 7.45%, P = .04). In patients who developed TTTS, all donors had VCI.

CONCLUSION

Ultrasound evaluation of abnormal CI at 11 + 0 to 13 + 6 weeks' gestation in MCDA twins is valuable in the assessment of the risk for TTTS.

The impact of chorionicity and the type of twin growth on the early neonatal outcome in twin pregnancies - 20 years of experience from one tertiary perinatal center

OBJECTIVE

Twin pregnancies are associated with higher neonatal mortality and morbidity. Growth discordance and monochorionicity are among the factors that worsen the course of pregnancy. The study aimed to assess neonatal conditions and mortality in relation to growth type and chorionicity.

MATERIALS AND METHODS

Data from 820 pregnant women with twin pregnancies and their 1640 newborns were analyzed. The Apgar score and umbilical artery blood pH, as well as the rate of complications, were compared between dichorionic diamniotic (DCDA) and monochorionic diamniotic (MCDA) twins with symmetric and discordant growth. The Student's t-test and the Pearson chi-square test were used for comparisons.

RESULTS

There were 576 (70.2%) DCDA pregnancies, including 421 (73.1%) with symmetric growth and 155 (26.9%) with discordant growth, and 244 (29.8%) MCDA pregnancies, including 110 (45.1%) with symmetric growth and 134 (54.9%) with discordant growth. A significantly greater percentage of twins with discordant growth occurred in women older than 34 years than in those that were younger. An Apgar score of ≤7 was significantly more common among MCDA discordant twins, while an arterial umbilical blood pH of <7.2 was more common among MCDA twins with symmetric growth. Early neonatal deaths (n = 29; 1.8%), respiratory disorders, and a birth weight of <1500 g were significantly more common in MCDA twins than in DCDA twins.

CONCLUSION

MCDA twins with growth discordance are burdened with a higher risk of neonatal morbidity and mortality than symmetric DCDA twins. Chorionicity and growth discordancy are important determinants of the outcome of twin pregnancy.

Two separate placental masses on ultrasound do not always indicate a dichorionic pregnancy

Monochorionic pregnancies are associated with a higher risk of perinatal morbidity and mortality than dichorionic pregnancies. Early determination of chorionicity by an ultrasound exam between 11⁺⁰ and 14⁺⁰ weeks' gestation (WG) is essential for the subsequent management of twin pregnancies. The presence of the T-sign is the most specific sign for determination of monochorionicity. During the second trimester, the presence of two distinct placental masses has a lower specificity in determining the chorionicity. We report here two cases of a monochorionic pregnancy with a bipartite placenta, suggesting that a placenta with two separate masses, each with a distinct cord insertion is not always indicative of a dichorionic pregnancy.'

Perinatal outcomes in Finnish twins: a retrospective study

BACKGROUND

To establish the changes in perinatal morbidity and mortality in twin pregnancies in Finland, a retrospective register research was conducted. Our extensive data from a 28-year study period provide important information on the outcome of twin pregnancies in Finland that has previously not been reported to this extent.

METHODS

All 23,498 twin pregnancies with 46,996 children born in Finland during 1987-2014 were included in the study. Data were gathered from the Medical Birth Register and the Hospital Discharge Register (Finnish Institute for Health and Welfare, Finland) regarding perinatal mortality (PNM) and morbidity. For statistical analysis, binomial regression analysis and crosstabs were performed. The results are expressed in means, percentages and ranges with comparison to singletons when appropriate. Odds ratios from binomial regression analysis are reported. A p-value <0.05 was considered statistically significant.

RESULTS

There were 46,363 liveborn and 633 stillborn twins in Finland during 1987-2014. Perinatal mortality decreased markedly, from 45.1 to 6.5 per 1000 for twin A and from 54.1 to 11.9 per 1000 for twin B during the study period. Yet, the PNM difference between twin A and B remained. Early neonatal mortality did not differ between twins, but has decreased in both. Asphyxia, respiratory distress syndrome, need for antibiotics and Neonatal Intensive Care Unit (NICU) stay were markedly more common in twin B.

CONCLUSIONS

In Finland, PNM and early neonatal mortality in twins decreased significantly during 1987-2014 and are nowadays very low. However, twin B still faces more complications. The outline provided may be used to further improve the monitoring and thus perinatal outcome of twins, especially twin B.

Longitudinal Doppler references for monochorionic twins and comparison with singletons

OBJECTIVES

To construct monochorionic (MC) twin-specific longitudinal Doppler references for umbilical artery pulsatility index (UA-PI), middle cerebral artery (MCA) PI and peak systolic velocity (PSV) and ductus venosus (DV) PI derived from a strictly selected cohort of uncomplicated MC twins. The secondary aim of the study was to compare our findings with singleton reference charts.

METHODS

A retrospective evaluation was made of all consecutive uncomplicated MC twin pregnancies referred to our Unit from 2010 to 2018. Fortnightly serial examinations were performed of UA-PI, MCA-PI, MCA-PSV and DV-PI, according with the clinical protocol, from 20 to 37 weeks of gestation. We included cases with at least four ultrasound examinations, delivery at our hospital and complete neonatal follow up. A two-step method was used to trace the estimated centile curves: estimation of the median was performed with appropriate fractional polynomials by a multilevel model and estimation of the external centiles through the residuals (quantile regression). The comparison with singletons was made by plotting the references derived from the present study on the referred charts commonly used for singletons.

RESULTS

The study group comprised 150 uncomplicated MC twin pairs. Estimated centiles (3rd, 5th, 10th, 50th, 90th, 95th, 97th) of UA-PI, MCA-PI, MCA-PSV and DV-PI in function of the gestational age are presented. The comparison with singletons showed substantial differences, with higher UA-PI and lower MCA-PI and PSV median values in MC twins. Median DV PI values were similar to the values for singletons, while the upper centiles were higher in MC twins.

CONCLUSIONS

This study sets out MC twin-specific longitudinal references for UA-PI, MCA-PI, MCA-PSV and DV-PI derived from the largest series of uncomplicated MC twin pregnancies presently available. The comparison with singleton reference values underscores the deviation from physiology that is intrinsic to these unique pregnancies and supports the need for MC twin-specific charts.

Counseling young women with early breast cancer on fertility preservation

PURPOSE

Women with early-stage breast cancer may still have a future child wish, while chemotherapy may impair fertility. To pursue on fertility preservation shortly after breast cancer diagnosis is complex. This review holds a critical reflection on all topics that need to be counseled to give them the opportunity to make a well-informed decision before starting any oncological treatment.

METHODS

A comprehensive literature review was performed on papers published in English language on breast cancer in young women, risk of chemotherapy-induced infertility, fertility preservation techniques, impact of possible mutation carriership, and future pregnancy outcome.

RESULTS

Below 40 years of age, the risk of permanent chemotherapy-induced ovarian function failure is approximately 20%, where taxanes do not significantly add to this risk. Overall, 23% of reported women who performed fertility preservation by cryopreserving oocytes or embryos returned for embryo transfer. Of these, 40% gave live birth. Both fertility preservation in women diagnosed with breast cancer and pregnancy after treatment seem safe with respect to breast cancer survival. Women who have a genetic predisposition for breast cancer like BRCA gene mutation should also be informed about the possibility of pre-implantation genetic diagnosis.

CONCLUSIONS

Women with an early stage of breast cancer and a possible future child wish should be referred to an expertise center in breast cancer, fertility preservation, and genetics in this complex decision-making process, shortly after diagnosis.

Cardiomegaly of the larger twin in monochorionic twin pregnancies warrants neonatal intensive care even without twin-to-twin transfusion syndrome

OBJECTIVES

Some monochorionic twin pregnancies need intensive cardiac management even in the absence of twin-to-twin transfusion syndrome after birth. The purpose of this study was to investigate risk factors related to persistent hypotension requiring cardiotonic agent use among monochorionic twin pregnancies without twin-to-twin transfusion syndrome.

STUDY DESIGN

This was a retrospective study of 316 monochorionic twin pregnancies without twin-to-twin transfusion syndrome (632 babies). All cases were treated in the neonatal intensive care unit. Hypotension was defined as mean arterial blood pressure below the norm for gestational age. Decreased left ventricular ejection fraction was defined as a value <60%. Dopamine, dobutamine and phosphodiesterase III inhibitor were used as cardiotonic agents for hypotension persisting even after adequate infusion.

RESULTS

Among the 632 cases, 33 (5.2%) needed cardiotonic agents for persistent hypotension. The frequency of persistent hypotension with decreased left ventricular ejection fraction was significantly higher among larger twins (4.4%) than among smaller twins (0.6%, p = 0.0038). In larger twins, multivariate analysis showed that Z-score for cardiothoracic area ratio (odds ratio, 2.31; p < 0.001), tricuspid regurgitation (odds ratio, 6.34; p = 0.015) and gestational age at delivery (odds ratio, 0.66; p < 0.001) correlated with persistent hypotension. In smaller twins, univariate analysis showed gestational age at delivery, birth weight, Z-score for birth weight and Z-score for cardiothoracic area ratio of the larger twin were related to persistent hypotension. Concentration of brain natriuretic peptide in the umbilical vein in larger and smaller twins were significantly correlated (coefficient of correlation = 0.792, p < 0.001).

CONCLUSIONS

In monochorionic twin pregnancies, attention needs to be given to cardiac size along with amniotic fluid and fetal growth. Both larger and smaller twins carry risks of persistent hypotension after birth. Close observation is needed, especially in cases where the larger twin displays cardiomegaly despite absence of twin-to-twin transfusion syndrome.

SMFM Special Statement: State of the science on multifetal gestations: unique considerations and importance

We sought to review the state of the science for research on multiple gestations. A literature search was performed with the use of PubMed for studies to quantify the representation of multiple gestations for a sample period (2012-2016) that were limited to phase III and IV randomized controlled trials, that were written in English, and that addressed at least 1 of 4 major pregnancy complications: fetal growth restriction or small-for-gestational-age fetus, gestational diabetes mellitus, preeclampsia, and preterm delivery. Of the 226 studies that are included in the analysis, multiple pregnancies were most represented in studies of preterm delivery: 17% of trials recruited both singleton and multiple pregnancies; another 18% of trials recruited only multiple pregnancies. For trials that studied preeclampsia, fetal growth restriction, and gestational diabetes mellitus, 17%, 8%, and 2%, respectively, recruited both singleton and multiple gestations. None of the trials on these 3 topics were limited to women with a multiple pregnancy. Women with a multiple pregnancy are at risk for complications similar to those of women with singleton pregnancies, but their risk is usually higher. Also, the pathophysiologic condition for some complications differs in multiple gestations from those that occur in singleton gestations. Conditions that are unique to multiple pregnancies include excess placenta, placental crowding or inability of the uteroplacental unit to support the normal growth of multiple fetuses, or suboptimal placental implantation sites with an increased risk of abnormal placental location. Other adverse outcomes in multiple gestations are also influenced by twin-specific risk factors, most notably chorionicity. Although twins have been well represented in many studies of preterm birth, these studies have failed to identify adequate predictive tests (short cervical length established over 2 decades ago remains the single best predictor), to establish effective interventions, and to differentiate the underlying pathophysiologic condition of twin preterm birth. Questions about fetal growth also remain. Twin growth deviates from that of singleton gestations starting at approximately 32 weeks of gestation; however, research with long-term follow-up is needed to better distinguish pathologic and physiologic growth deviations, which include growth discordance among pairs (or more). There are virtually no clinical trials that are specific to twins for gestational diabetes mellitus or preeclampsia, and subgroups for multiple pregnancies in existing trials are not large enough to allow definite conclusions. Another important area is the determination of appropriate maternal nutrition or micronutrient supplementation to optimize pregnancy and child health. There are also unique aspects to consider for research design in multiple gestations, such as designation and tracking of the correct fetus prenatally and through delivery. The correct statistical methods must be used to account for correlated data because multiple fetuses share the same mother and intrauterine environment. In summary, multiple gestations often are excluded from research studies, despite a disproportionate contribution to national rates of perinatal morbidity, mortality, and health-care costs. It is important to consider the enrollment of multifetal pregnancies in studies that target mainly women with singleton gestations, even when sample size is inadequate, so that insights that are specific to multiple gestations can be obtained when results of smaller studies are pooled together. The care of pregnant women with multiple gestations presents unique challenges; unfortunately, evidence-based clinical management that includes the diagnosis and treatment of common obstetrics problems are not well-defined for this population.

Ultrasonographic evaluation of feto-placental tissues at different intrauterine locations in rabbit

The main purpose of examining multiparous species with real-time ultrasonography is to determine the gestational age and make various fetal measurements for early diagnosis of growth anomalies and sibling mismatches. This study investigated changes in fetometric measurements, obstetric Doppler indices and placental image analysis results based on gestational age and fetal location in fetuses located cranially and caudally between 16 and 24 days gestation in 22 healthy pregnant New Zealand rabbits. The first study group consisted of fetuses positioned at the cranial end (n = 22) while the second group consisted of fetuses positioned at the caudal end (n = 22) in each pregnancy. Fetal biparietal head diameter (BPD) and trunk diameter (TD) were measured, and mean grayness values (MGV) were determined from placental image analysis of each fetus. Using Doppler USG, the pulsatile (PI) and resistance (RI) indices of the uterine artery (UtA) and umbilical artery (UmA) were recorded. By the end of the study, BPD and TD values for cranial and caudal fetuses had significantly increased with gestational age (P < 0.001). The MGV values of caudal fetuses were significantly higher (except for the 16th day) (P < 0.05). The UtA PI value of the caudal fetuses was significantly higher (except for the 18th day) (P < 0.01). The UtA RI values of caudal fetuses were significantly higher than cranial ones on the 16 and 24th days (P < 0.05). The PI of the UmA increased until the 20th day before decreasing significantly in both study groups (P < 0.001). The UmA RI value decreased according to the gestational age in both groups (P < 0.001). It was significantly higher in the caudal fetuses on the 20th day (P < 0.05). The somatic rate of all fetuses peaked at the end of the second trimester, although caudal fetuses had higher fetometric values, and this location difference also affected placental echotexture. In both vessels of caudal fetuses, pulsatility and resistance values were higher. The 20th day of pregnancy was a threshold for the Doppler exam results. In conclusion, growth and metabolic status of fetuses located in different uterine locations in healthy pregnant New Zealand rabbits vary. Based on the these growth curves and hemodynamic data, more comprehensive studies of intrauterine life may be possible.

Obstetrical Outcomes of Amniocentesis or Chorionic Villus Sampling in Dichorionic Twin Pregnancies

BACKGROUND

Under certain situations, women with twin pregnancies may be counseled to undergo invasive prenatal diagnostic testing. Chorionic villus sampling and amniocentesis are the two generally performed invasive prenatal diagnostic tests. Studies comparing procedure-related fetal loss between first-trimester chorionic villus sampling and second-trimester amniocentesis in twin pregnancies are limited. This study aimed to evaluate the procedure-related fetal loss and the obstetrical outcomes of these two procedures, chorionic villus sampling and amniocentesis in twin pregnancies.

METHODS

The data from dichorionic-diamniotic twin pregnancies on which first-trimester chorionic villus sampling (n = 54) or second-trimester amniocentesis (n = 170) was performed between December 2006 and January 2017 in a single center were retrospectively analyzed. The procedure-related fetal loss was classified as loss of one or all fetuses within 4 weeks of procedure, and overall fetal loss was classified as loss of one or all fetuses during the gestation. The groups were compared with respect to the procedure-related and obstetrical outcomes.

RESULTS

The difference in proportion of procedure-related fetal loss rate (1.9% for chorionic villus sampling vs. 1.8% for amniocentesis; P = 1.000) and the overall fetal loss rate (7.4% for chorionic villus sampling vs. 4.7% for amniocentesis; P = 0.489) between the two groups was not significant. The mean gestational ages at delivery were not statistically significant.

CONCLUSION

Both the overall fetal loss rate and the procedure-related fetal loss rate of chorionic villus sampling and amniocentesis in dichorionic twin pregnancies had no statistical significance. Both procedures can be safely used individually.

First-trimester ultrasound measurements and maternal serum biomarkers as prognostic factors in monochorionic twins: a cohort study

BACKGROUND

Monochorionic twin pregnancies are at high risk of adverse outcomes, but it is not possible to predict which pregnancies will develop complications. The aim of the study was to evaluate, in monochorionic twin pregnancies, whether first-trimester ultrasound (nuchal translucency [NT], crown-rump length [CRL]), and maternal serum biomarkers (alpha-fetoprotein [AFP], soluble fms-like tyrosine kinase-1 [sFlt-1] and placental growth factor [PlGF]), are prognostic factors for fetal adverse outcome composite, twin-twin transfusion syndrome (TTTS), growth restriction, and intrauterine fetal death (IUFD).

METHODS

A cohort study of 177 monochorionic diamniotic twin pregnancies. Independent prognostic ability of each factor was assessed by multivariable logistic regression, adjusting for standard prognostic factors. Factors were analysed as continuous data; thus, the reported ORs relate to either 1% change in NT or CRL inter-twin percentage discordance or one unit of measure in each serum biomarker.

RESULTS

The odds of the fetal adverse outcome composite were significantly associated with increased NT inter-twin percentage discordance (adjusted OR 1.03 [95% CI 1.01, 1.06]) and CRL inter-twin percentage discordance (adjusted OR 1.17 [95% CI 1.07, 1.29]). TTTS was significantly associated with increased NT discordance (adjusted OR 1.06 [95% CI 1.03, 1.10]) and decreased PlGF (adjusted OR 0.42 [95% CI 0.19, 0.93]). Antenatal growth restriction was significantly associated with increased CRL discordance (adjusted OR 1.20 [95% CI 1.08, 1.34]). Single and double IUFD were associated with decreased PlGF (adjusted OR 0.34 [95% CI 0.12, 0.98]) and (adjusted OR 0.18 [95%CI 0.05, 0.58]) respectively.

CONCLUSIONS

This study has identified potential individual prognostic factors in the first trimester (fetal biometric and maternal serum biomarkers) that show promise but require further robust evaluation in a larger, prospective series of MC twin pregnancies, so that their usefulness both individually and in combination can be defined.

TRIAL REGISTRATION

ISRCTN 13114861 (retrospectively registered).

Comparison of neonatal outcomes of very low birth weight infants by mode of conception: in vitro fertilization versus natural pregnancy

OBJECTIVE

To compare the neonatal outcomes of very low birth weight (VLBW) infants born after IVF with those of VLBW infants born after natural pregnancy (NP).

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 6,871 VLBW infants born from January 2014 to December 2016.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Neonatal mortality and morbidities.

RESULT(S)

Of the 6,871 VLBW infants enrolled, 4,438 infants were born as singletons (IVF = 271; NP = 4,167), and 2,433 infants were born as multiplets (IVF = 1,301; NP = 1,132). After adjustment for maternal and neonatal baseline characteristics, infants born as singletons earlier than 28 weeks after IVF more frequently had high-stage retinopathy of prematurity than those born after NP, whereas infants born as multiplets between 28 and 31 weeks after IVF had fewer major congenital anomalies, high-grade intraventricular hemorrhage, and periventricular leukomalacia than those born after NP. Otherwise, no differences in mortality and neonatal outcomes were found.

CONCLUSION(S)

Very low birth weight infants born as singletons after IVF had comparable neonatal outcomes to those born after NP, except for an increased risk of high-stage retinopathy of prematurity. Very low birth weight infants born as multiplets after IVF had fewer neurologic morbidities than those born after NP.

Prediction of birth weight in twin pregnancies using fractional limb volumes by three-dimensional ultrasonography

Objective: To predict birth weight using fetal fractional limb volumes (FLVs) by three-dimensional (3D) ultrasonography in twin pregnancies.Method: This prospective observational cohort study evaluated 51 twin pregnancies, including 28 dichorionic and 23 monochorionic pregnancies. Ultrasound examinations were performed up to 5 d before delivery. Birth weight prediction models were developed using the fractional arm volume (FAV), fractional thigh volume (FTV), and Hadlock's formula and were compared with the actual birth weight.Results: The mean gestational age at the time of ultrasound examination was 35.3 weeks. The mean birth weight was slightly higher in dichorionic than in monochorionic pregnancies 2391.2 versus 2352.4 g. The measurements using FTV were the closest to actual birth weights. For the total group, the Hadlock formula had mean percentage change of 7.18% while the FTV model presented mean percentage change of 6.62% in relation to birth weight. However, no significant difference was noted between Hadlock's formula and FTV p = .363 and .678 for dichorionic and monochorionic pregnancies, respectively.Conclusions: FTV accurately predicted birth weight in twin monochorionic and dichorionic pregnancies. However, Hadlock's formula should still be used.

Perinatal outcome of twin pregnancies according to maternal age

Objective

To investigate the perinatal outcomes of twin pregnancies according to maternal age.

Methods

This is a retrospective cohort study of twin pregnancies delivered ≥24 weeks' gestation at a tertiary academic hospital from 1995 to 2016. Subjects were categorized into 5 groups according to maternal age: <25, 25–29, 30–34, 35–39, and ≥40 years. Maternal and neonatal outcomes of each maternal age group were analyzed using the Jonckheere-Terpstra test and the linear-by-linear association test.

Results

A total of 1,936 twin pregnant women were included, of which 47 (2.4%), 470 (24.3%), 948 (49.0%), 417 (21.5%), and 54 (2.7%) women were aged <25, 25–29, 30–34, 35–39, and ≥40 years, respectively. Higher maternal age was significantly associated with a higher rate of dichorionic twins and a higher risk of gestational diabetes and placenta previa. However, rates of preterm labor, preterm premature rupture of membranes, cervical incompetence, preterm delivery, preeclampsia, placenta abruption, and cesarean section were not associated with maternal age. Birth weight increased and the rate of admission to the neonatal intensive care unit (NICU) decreased with older maternal age, but other neonatal outcomes did not change with age. Maternal age was significantly associated with a lower rate of NICU admission after controlling for potential confounding factors in multivariable analysis.

Conclusion

Advanced maternal age in twin pregnancies was associated with increased risk of gestational diabetes, placenta previa, and higher birth weight but a lower rate of NICU admission. However, other outcomes were not significantly associated with maternal age.

The place of antenatal corticosteroids in late preterm and early term births

Infants born in the late preterm period and via non-labour caesarean section in the early term period are at increased risk of respiratory morbidity when compared to their term-born counterparts. The morbidity in these infants is less frequent and severe than in early preterm infants. Antenatal corticosteroids reduce respiratory morbidity in these populations; however, the magnitude of the reduction appears to be small and predominantly in the self-limiting condition of transient tachypnoea of the neonate. The smaller benefit, along with possible harmful effects of corticosteroids, raises a question about the role of antenatal corticosteroids in this population. Special obstetric populations such as twin pregnancies and pregnancies complicated by diabetes and growth restriction are at increased risk of prematurity and more vulnerable to its complications. Nevertheless, there is limited evidence regarding the benefits of corticosteroids in these populations and potential concern regarding adverse effects. We recommend an individualised approach when administering corticosteroids at later gestations. In these specific obstetric populations, we do not currently recommend administering corticosteroids in the late preterm/early term periods until more evidence is available.

The burden to be second twin: a population-based study of 2686 twins: (2124 dichorionic). Proposal of the concept of mobility

Objectives: To identify if there is a specific neonatal morbidity/mortality among second twins relative to first twins.Study design: A 17-year (2001-2017) population-based observational cohort of all twin newborns born in the South of Reunion island after 21 weeks.Results: Among 1062 dichorionic (DTP) and 281 monochorionic twin pregnancies (2686 newborns), twin 2 have a doubled risk to be in breech presentation and a bad Apgar at 1 mn (≤6) in vaginal deliveries. Specific to dichorionic pregnancies, twin 2 were lighter by 50-60 g than twin 1, had higher rates of intrauterine growth retardation (IUGR), OR 1.33, p = .007, a doubled risk to have congenital abnormalities OR 2.1, p = .006.Conclusion: In dichorionic twin pregnancies, second twins having a doubled prevalence of severe congenital abnormalities are not completely elucidated and deserves further research. (1) We propose that twin 2 presenting higher risks of being IUGR and much higher risks of severe malformations suggest that during pregnancy, the less mobile of the two twins is "relegated" to the back of the uterus. (2) For interventions in the delivery room, systematically the most experimented neonatologist should plan to manage the second twin because significantly twin 2 presents higher problems than twin 1.

Consensus definition and essential reporting parameters of selective fetal growth restriction in twin pregnancy: a Delphi procedure

OBJECTIVES

Twin pregnancy complicated by selective fetal growth restriction (sFGR) is associated with increased perinatal mortality and morbidity. Inconsistencies in the diagnostic criteria for sFGR employed in existing studies hinder the ability to compare or combine their findings. It is therefore challenging to establish robust evidence-based management or monitoring pathways for these pregnancies. The main aim of this study was to determine, by expert consensus using a Delphi procedure, the key diagnostic features of and the essential reporting parameters in sFGR.

METHODS

A Delphi process was conducted among an international panel of experts in sFGR in twin pregnancy. Panel members were provided with a list of literature-based parameters for diagnosing sFGR and were asked to rate their importance on a five-point Likert scale. Parameters were described as solitary (sufficient to diagnose sFGR, even if all other parameters are normal) or contributory (those that require other abnormal parameter(s) to be present for the diagnosis of sFGR). Consensus was sought to determine the cut-off values for accepted parameters, as well as parameters used in the monitoring, management and assessment of outcome of twin pregnancy complicated by sFGR. The questions were presented in two separate categories according to chorionicity.

RESULTS

A total of 72 experts were approached, of whom 60 agreed to participate and entered the first round; 48 (80%) completed all four rounds. For the definition of sFGR irrespective of chorionicity, one solitary parameter (estimated fetal weight (EFW) of one twin < 3^rd centile) was agreed. For monochorionic twin pregnancy, at least two out of four contributory parameters (EFW of one twin < 10^th centile, abdominal circumference of one twin < 10^th centile, EFW discordance of ≥ 25%, and umbilical artery pulsatility index of the smaller twin > 95^th centile) were agreed. For sFGR in dichorionic twin pregnancy, at least two out of three contributory parameters (EFW of one twin < 10^th centile, EFW discordance of ≥ 25%, and umbilical artery pulsatility index of the smaller twin > 95^th centile) were agreed.

CONCLUSIONS

Consensus-based diagnostic features of sFGR in both monochorionic and dichorionic twin pregnancies, as well as cut-off values for the parameters involved, were agreed upon by a panel of experts. Future studies are needed to validate these diagnostic features before they can be used in clinical trials of interventions. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Associations of gestational age with child health and neurodevelopment among twins: A nationwide Japanese population-based study

BACKGROUND

The prevalence of multiple births has recently increased. However, the association between gestational age and long-term morbidity among twins remains unclear.

AIMS

To examine the association of gestational age with child health and neurological development in early childhood among twins.

STUDY DESIGN

Population-based longitudinal study.

SUBJECTS

We included 947 children from 479 pairs of twins with information on gestational age.

OUTCOME MEASURES

Hospitalization was used as an indicator of physical health, and responses to questions about age-appropriate behaviors were used as an indicator of neurobehavioral development. We conducted binomial log-linear regression analyses, controlling for both child and maternal variables in the model. We accounted for correlations within the pairs with generalized estimating equations.

RESULTS

The early term group (i.e., 37 to 38 weeks of gestation) had a lower risk of poor child health and unfavorable neurodevelopment compared with the full term group (≥39 weeks of gestation) and preterm group (<37 weeks of gestation). Compared with the early term group, the adjusted risk ratios for hospitalization for all causes during the period from 7 to 18 months of age was 2.2 (95% confidence interval: 1.3-3.8) for very preterm children (<32 weeks of gestation), 1.1 (0.8-1.6) for moderately and late preterm children (32 to 36 weeks of gestation), and 1.8 (1.0-3.2) for full term children.

CONCLUSION

We observed a U-shaped association of gestational age with child health and neurodevelopment. The early term group had the lowest risk of poor outcomes among twins.

The value of ultrasound in predicting isolated inter-twin discordance and adverse perinatal outcomes

PURPOSE

To investigate the value of ultrasound approaching delivery to predict isolated inter-twin discordance and adverse perinatal outcomes.

METHODS

We retrospectively included twin pregnancies with sonography approaching delivery in ten maternal-foetal medicine centres in China from 2013 to 2014. Estimated foetal weight (EFW) and inter-twin EFW disparity (EFWD) were calculated based on biometry parameters. Percentage errors between EFW and actual birthweight or between EFWD and actual inter-twin disparity were calculated. ROC curves and multiple logistic regression were applied to evaluate the ability of EFWD to predict inter-twin disparity ≥ 25%, stillbirth, asphyxia and admission to a neonatal intensive unit (NICU). Chorionicity-stratified analysis was further performed.

RESULTS

Two hundred sixty-six monochorionic and 760 dichorionic twin pregnancies were analysed. The percentage errors in foetal weight estimations were 7-13%, whereas percentage errors in the estimation of inter-twin disparity were nearly 100%. Among eight formulas, Hadlock1 performed best, with a detectable rate of 65% and a false positive rate of 5% when predicting inter-twin disparity ≥ 25%. EFWD ≥ 22% was strongly associated with stillbirth (OR = 4.17, 95% CI 1.40-12.40) and NICU admission (OR = 3.48, 95% CI 2.03-5.97) after adjustment for gestational age, parity and abnormal umbilical systolic/diastolic ratio. Ultrasound had better predictive ability in monochorionic twins.

CONCLUSION

The predictive value of ultrasound for isolated inter-twin discordance and adverse perinatal outcomes was limited, which was possibly due to the magnifying of systematic errors in the disparity estimation compared with weight estimation. Despite this, abnormal biometry was an independent contributor for the poor prognosis of neonates.

Falling perinatal mortality in twins in the UK: organisational success or chance?

In June 2018, Mothers and Babies Reducing Risks through Audits and Confidential Enquiries across the UK (MBRRACE-UK) published a Perinatal Surveillance report of an audit between 2013-2016. This noted that the stillbirth rate for twins nearly halved between 2014-2016; whereas the stillbirth rate for singletons remained static. There was a statistically significant reduction in the rate of stillbirth in twins over this period from 11.07 (95% CI, 9.78-12.47) to 6.16 (95% CI, 5.20-7.24) per 1000 total births. This commentary discusses these observations, the effects of twin chorionicity, and the potential obstetric and neonatal interventions, as well as public health improvements, that may have influenced these findings.

The effects of birth order on neonatal outcomes in early-preterm, late-preterm and term twin infants

Objectives: Birth order is one of the main factors that influences the neonatal outcome of twins. However, there is little prior data regarding the effect of birth order under different clinical circumstances. This study investigates the effect of birth order on the neonatal outcomes of twins delivered during early-preterm, late-preterm and term gestations according to chorionicity, delivery mode and indication for delivery.Methods: This is a retrospective cohort study of women with twin pregnancies delivered at 24-40 weeks of gestation between 1995 and 2014. We excluded twin pregnancies with the following complications: twin-to-twin transfusion syndrome, monoamnionic twins, delayed interval delivery and fetal death, chromosomal anomalies or major congenital malformation in one or more of the twins. The neonatal outcomes, including death, admission to neonatal intensive care unit (NICU), mechanical ventilator support, and respiratory distress syndrome (RDS) was compared between the first and second twin born at early-preterm (24-33 weeks of gestation), late-preterm (34-36 weeks of gestation) and term (≥37 weeks of gestation) gestations. These outcomes were further analyzed according to chorionicity, mode of delivery and indication for delivery by multivariable analysis (after adjusting for sex, presentation, and birth weight).Results: Among a total of 1,614 women with twin pregnancies who met the selection criteria, 423, 674 and 517 women delivered at early-preterm, late-preterm and term gestation, respectively. Overall, the second-born twins were lighter and had higher rates of NICU admission, mechanical ventilator support, and RDS than did first-born twins. Second twins born at early-preterm gestation had higher rates of RDS and mechanical ventilator support than did first twins. Second twins born at late-preterm gestation had higher rates of NICU admission and mechanical ventilator support than did first twins. Second twins born at term gestation also had a higher NICU admission rate than did first twins. However, in the multivariable analysis of the subgroups, the rates of NICU admission, mechanical ventilator support and RDS were not significantly different between most twin pairs. However, there were several significant differences. There was a higher risk of RDS in the second twins in the early-preterm premature rupture of membranes (PROM) subgroup, and a higher risk of mechanical ventilator support in the late-preterm PROM subgroup. Low birth weight was the only significant factor independently associated with a higher risk of adverse neonatal outcome in the second twins compared with the first twins in all subgroups.Conclusions: Second twins born at early-preterm, late-preterm and term were at higher risk of adverse neonatal outcome than were their respective first twins. However, this finding was mainly represented lower birth weight of the second twin. Still, second twins delivered due to early-preterm and late-preterm PROM had a higher risk of RDS and mechanical ventilator support, respectively, than did the first twin after adjusting for birth weight.

Comparison of neurodevelopmental outcomes between monochorionic and dichorionic twins with birth weight ≤ 1500 g in Japan: a register-based cohort study

OBJECTIVE

To examine the relationship between chorionicity and neurodevelopmental outcomes in very low birth weight twins at 3 years of age.

STUDY DESIGN

A retrospective cohort study of 3538 twins who were admitted to 91 tertiary perinatal centers in the Neonatal Research Network of Japan between 2003 and 2012.

RESULTS

In a comparison of the followed-up 796 monochorionic twins and 786 dichorionic twins, the overall rate of neurodevelopmental impairment was higher in monochorionic twins; specifically, the rate of disability in the language-social area of the Japanese standardized developmental test was higher in monochorionic twins than in dichorionic twins (adjusted odds ratio, 1.55; 95% confidence interval, 1.07-2.25; P = 0.02).

CONCLUSIONS

Chorionicity was associated with neurodevelopmental outcome (especially for language and social development) in a large cohort of very low birth weight twins who had a high rate of perinatal morbidity and neurodevelopmental impairment.

Placental characteristics in monochorionic twins with selective intrauterine growth restriction in relation to the umbilical artery Doppler classification

INTRODUCTION

The objective of this study was to evaluate the placental characteristics of monochorionic twin pregnancies with selective intrauterine growth restriction (sIUGR) classified according to the Gratacós classification based on umbilical artery Doppler measurements.

METHODS

All consecutive placentas from monochorionic twin pregnancies with sIUGR, (defined as a birthweight discordance > 25% and/or an estimated fetal weight in one twin <10th centile) examined between May 2002 and February 2018 were included in the study. Each placenta was injected with colored dye to study the angioarchitecture. Primary outcomes were placental share discordance and diameter of the arterio-arterial anastomoses in relation to the umbilical artery Doppler types of sIUGR (Gratacós classification).

RESULTS

Of the 83 sIUGR twins included, 27 were classified as Gratacós type I, 24 as type II and 32 as type III. The median gestational age at delivery was 34.3 weeks for type I, compared to 31.2 weeks and 31.6 weeks for type II and type III respectively. A trend towards a higher placental share discordance in type III sIUGR was observed. The median arterio-arterial diameter was 1.7 mm (0.8-2.6) in type I, 1.7 mm (1.2-2.2) in type II and 2.8 (2.0-3.5) mm in type III (p < 0.01).

DISCUSSION

Type III sIUGR placentas appear to be characterized by a larger diameter of the arterio-arterial anastomoses and a larger placental share discordance compared to type I and II sIUGR. The insights in the placental architecture of sIUGR placentas may offer new views on the pathophysiology of the disease.

Pitfalls in assessing chorioamnionicity: novel observations and literature review

Accurate diagnosis of chorioamnionicity in multiple pregnancies is the key to appropriate clinical management of multiple gestation. Although prenatal ultrasound assessment of chorioamnionicity is well established and highly accurate if performed in early pregnancy, exceptions and artifacts arise from anatomic variations in multiple pregnancies and unusual sonographic features do exist. We have summarized our own experiences and reports from the literature on these pitfalls as follows: (1) discordant fetal sex in monochorionic pregnancies due to sex chromosome abnormalities, genital malformation in 1 fetus, or dizygotic twins forming a monochorionic placenta; (2) separate placental masses in monochorionic pregnancies due to bipartite placenta; (3) false-negative and false-positive λ sign can arise for various reasons, and in partial monochorionic/dichorionic placentas both T and λ sign may co-exist; (4) intrauterine synechia appearing as a thick and echogenic intrauterine septum may lead to erroneous diagnosis of dichorionic twins; and (5) errors in ascertaining amnionicity by the visualization of thin intertwin amniotic membranes and the number of yolk sacs. The ultrasound techniques to reduce inaccuracy in prenatal determination of chorioamnionicity and the use of single nucleotide polymorphisms based on noninvasive prenatal test to determine zygosity are also reviewed.

Twin-to-twin transfusion syndrome neurodevelopmental follow-up study (neurodevelopmental outcomes for children whose twin-to-twin transfusion syndrome was treated with placental laser photocoagulation)

Background

Twin-to-twin transfusion syndrome (TTTS) is a serious complication of 10–15% of twin or triplet pregnancies in which multiple fetuses share a single placenta. Communicating placental vessels allow one fetus (the donor) to pump blood to the other (the recipient). Mortality rates without intervention are high, approaching 100% in some series, with fetal deaths usually due to cardiac failure. Surgical correction using laser photocoagulation of communicating placental vessels was developed in the 1980s and refined in the 1990s. Since it was introduced in Victoria in 2006, laser surgery has been performed in approximately 120 pregnancies.

Survival of one or more fetuses following laser surgery is currently > 90%, however the neurodevelopmental outcomes for survivors remain incompletely understood. Prior to laser therapy, at least one in five survivors of TTTS had serious adverse neurodevelopmental outcomes (usually cerebral palsy). Current estimates of neurological impairment among survivors following laser surgery vary from 4 to 31% and long-term follow-up data are limited.

Methods

This paper describes the methodology for a retrospective cohort study in which children aged 24 months and over (corrected for prematurity), who were treated with laser placental photocoagulation for TTTS at Monash Health in Victoria, Australia, will undergo comprehensive neurodevelopmental assessment by a multidisciplinary team. Evaluation will include parental completion of pre-assessment questionnaires of social and behavioural development, a standardised medical assessment by a developmental paediatrician or paediatric neurologist, and age-appropriate cognitive and academic, speech and fine and gross motor assessments by psychologists, speech and occupational therapists or physiotherapists. Assessments will be undertaken at the Murdoch Children’s Research Institute/Royal Children’s Hospital, at Monash Health or at another mutually agreed location. Results will be recorded in a secure online database which will facilitate future related research.

Discussion

This will be the first study to report and evaluate neurodevelopmental outcomes following laser surgery for twin-to-twin transfusion syndrome in Victoria, and will inform clinical practice regarding follow-up of children at risk of adverse outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1230-8) contains supplementary material, which is available to authorized users.

Weight discordance and perinatal mortality in twin pregnancy: systematic review and meta-analysis

OBJECTIVES

The primary aim of this systematic review was to explore the strength of association between birth-weight (BW) discordance and perinatal mortality in twin pregnancy. The secondary aim was to ascertain the contribution of gestational age and growth restriction in predicting mortality in growth-discordant twins.

METHODS

MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched. Only studies reporting on the risk of mortality in twin pregnancies affected compared with those not affected by BW discordance were included. The primary outcomes explored were incidence of intrauterine death (IUD), neonatal death (NND) and perinatal death. Outcome was assessed separately for monochorionic (MC) and dichorionic (DC) twin pregnancies. Analyses were stratified according to BW discordance cut-off (≥ 15%, ≥ 20%, ≥ 25% and ≥ 30%) and selected gestational characteristics, including incidence of IUD or NND before and after 34 weeks' gestation, presence of at least one small-for-gestational age (SGA) fetus in the twin pair and both twins being appropriate-for-gestational age. Risk of mortality in the larger vs smaller twin was also assessed. Meta-analyses using individual data random-effects logistic regression and meta-analyses of proportion were used to analyze the data.

RESULTS

Twenty-two studies (10 877 twin pregnancies) were included in the analysis. In DC pregnancies, a higher risk of IUD, but not of NND, was observed in twins with BW discordance ≥ 15% (odds ratio (OR) 9.8, 95% CI, 3.9-29.4), ≥ 20% (OR 7.0, 95% CI, 4.15-11.8), ≥ 25% (OR 17.4, 95% CI, 8.3-36.7) and ≥ 30% (OR 22.9, 95% CI, 10.2-51.6) compared with those without weight discordance. For each cut-off of BW discordance explored in DC pregnancies, the smaller twin was at higher risk of mortality compared with the larger one. In MC twin pregnancies, excluding cases affected by twin-twin transfusion syndrome, twins with BW discordance ≥ 20% (OR 2.8, 95% CI, 1.3-5.8) or ≥ 25% (OR 3.2, 95% CI, 1.5-6.7) were at higher risk of IUD, compared with controls. MC pregnancies with ≥ 25% weight discordance were also at increased risk of NND (OR 4.66, 95% CI, 1.8-12.4) compared with those with concordant weight. The risk of IUD was higher when considering discordant pregnancies involving at least one SGA fetus. The overall risk of mortality in MC pregnancies was similar between the smaller and larger twin, except in those with BW discordance ≥ 20%.

CONCLUSION

DC and MC twin pregnancies discordant for fetal growth are at higher risk of IUD but not of NND compared with pregnancies with concordant BW. The risk of IUD in BW-discordant DC and MC twins is higher when at least one fetus is SGA. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Evaluation of placental vascularization indices in monochorionic diamniotic and dichorionic diamniotic twin pregnancies

OBJECTIVES

We aimed to investigate and compare placental vascularization indices between monochorionic-diamniotic, dichorionic-diamniotic normal twin pregnancies, and normal singular pregnancies. We hypothesized that there is correlation between placental three-dimensional power Doppler vascularization indices and birth weight in case of twin pregnancies, and that normal singular pregnancies have higher placental vascularization indices than normal twin pregnancies.

STUDY DESIGN

Placental three-dimensional power Doppler vascularization indices, such as vascularization index, flow index, and vascularization-flow index were measured in monochorionic-diamniotic (N = 15) and dichorionic-diamniotic (N = 36) normal twin pregnancies, and in normal singular (N = 109) pregnancies. Correlations were analyzed between vascularization indices, and birth weight, APGAR score, umbilical pH, umbilical venous bicarbonate, lactate, and base excess.

RESULTS

Vascularization indices and birth weight were significantly (p < 0.01) higher in normal singular gestations (vascularization index = 10.36, flow index = 46.08, vascularization-flow index = 4.08, average birth weight = 3377 g at 38.2 weeks average gestational age) compared to monochorionic-diamniotic and dichorionic-diamniotic normal twin pregnancies. No significant differences were found in vascularization indices between monochorionic-diamniotic and dichorionic-diamniotic normal twins. There were no significant differences in APGAR score, umbilical pH, umbilical venous bicarbonate, lactate, and base excess between groups examined (p < 0.01). We found strong linear correlations between placental vascularization indices and birth weight in both twin groups.

CONCLUSION

Placental three-dimensional power Doppler vascularization indices seem appropriate for predicting birth weight in monochorionic-diamniotic and dichorionic-diamniotic normal twin pregnancies. Our pilot study revealed reference values for vascularization indices in case of twin pregnancies examined.

Delivery of the second twin: influence of presentation on neonatal outcome, a case controlled study

Background

Spontaneous vaginal twin delivery after 32nd week of gestation is safe when first twin presenting cephalic. Aim of this study is to identify obstetric factors influencing the condition of second twin and to verify whether non-cephalic presentation and vaginal breech delivery of the second twin is safe.

Methods

This is a retrospective case controlled cohort study of 717 uncomplicated twin deliveries ≥32 + 0 weeks of gestation from 2005 to 2014 in two tertiary perinatal centers. Obstetric parameters were evaluated in three groups with descriptive, univariate logistic regression analysis for perinatal outcome of second twins.

Results

The three groups included twins delivered by elective cesarean section ECS (n = 277, 38.6%), by unplanned cesarean section UPC (n = 233, 32.5%) and vaginally (n = 207, 28.9%). Serious adverse fetal outcome is rare and we found no differences between the groups. Second twins after ECS had significant better umbilical artery UA pH (p < 0.001) and better Apgar compared to UPC (p = 0.002). Variables for a fetal population “at risk” for adverse neonatal outcome after vaginal delivery (UA pH < 7.20, Apgar 5´ < 9) were associated with higher gestational age (p = 0.001), longer twin-twin interval (p = 0.05) and vacuum extraction of twin A (p = 0.04). Non-cephalic presentation of second twins was not associated (UA pH < 7.20 OR 1.97, CI 95% 0.93–4.22, p = 0.07, Apgar 5´ < 9 OR 1.63, CI 95% 0.70–3.77, p = 0.25, Transfer to neonatal intermediate care unit p = 0.48). Twenty-one second twins (2,9%) were delivered by cesarean section following vaginal delivery of the first twin. Even though non-cephalic presentation was overrepresented in this subgroup, outcome variables were not significantly different compared to cephalic presentation.

Conclusions

Even though elective cesarean means reduced stress for second twins this seems not to be clinically relevant. Non-cephalic presentation of the second twin does not significantly influence the perinatal outcome of the second twin but might be a risk factor for vaginal-cesarean birth.