Naturally conceived twins with monochorionic placentation have the highest risk of fetal loss

Retrospective comparison of monochorionic diamniotic twin pregnancies stratified by spontaneous or artificial conception

OBJECTIVES

To compare outcomes of monochorionic diamniotic (MCDA) twin pregnancies by in vitro fertilization (IVF) vs. spontaneously conceived counterparts.

METHODS

Retrospective comparison. Data about MCDA twin pregnancies, conceived spontaneously or by IVF, attending the Twin Pregnancy Care Unit of Sant'Anna Hospital in Turin (Italy) between January 1st 2010 and March 31st 2022, were collected retrospectively. Obstetric, fetal, and neonatal outcomes of MCDA twin pregnancies by IVF were compared to those of spontaneously conceived counterparts. Data were described by univariate and multivariate analysis.

RESULTS

541 MCDA twin pregnancies were included in the study, among which 45 conceived by IVF and 496 spontaneously conceived. Women with IVF twins were older than those who conceived spontaneously (36.7 ± 5.7 vs. 32.1 ± 5.2 years; p<0.001). No significant difference in the prevalence of pregnancy complications between the two groups was found, except for an increased incidence of hypertensive disorders among IVF pregnancies (17.8 vs. 8.5 %; p=0.039), which resulted nonsignificant after adjusting for maternal age and parity (aOR 1.9, 95 % CI 0.8-4.6). Data about 1,046 live born babies (90 conceived by IVF and 956 spontaneously) were also collected: perinatal outcomes did not differ between the two groups.

CONCLUSIONS

Our results suggest that MCDA twin pregnancies following IVF are not at increased risk of adverse outcomes compared to spontaneous MCDA twin pregnancies.

Pregnancy and neonatal outcomes of monozygotic twins resulting from assisted reproductive technology: a 10-year retrospective study

BACKGROUND

Monozygotic twins (MZTs) are associated with high risks of maternal and fetal complications. Even with the widely used elective single embryo transfer (SET), the risk of MZTs following assisted reproductive technology (ART) treatments remains. However, most studies of MZTs focused on the relevant etiology, with few studies describing pregnancy and neonatal outcomes.

METHODS

This retrospective cohort study included 19,081 SET cycles resulting from in-vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), preimplantation genetic testing (PGT) and testicular sperm aspiration (TESA) performed between January 2010 and July 2020 in a single university-based center. A total of 187 MZTs were included in this investigation. The main outcome measures were the incidence, pregnancy and neonatal outcomes of MZTs. Multivariate logistic regression analysis was performed to figure out the risk factors for pregnancy loss.

RESULTS

The overall rate of MZTs from ART treatment in SET cycles was 0.98%. No significant difference was found in the incidence of MZTs among the four groups (p = 0.259). The live birth rate of MZTs in the ICSI group (88.5%) was significantly more favorable than in the IVF, PGT and TESA groups (60.5%, 77.2% and 80%, respectively). IVF resulted in a significantly increased risk of pregnancy loss (39.4%) and early miscarriage (29.5%) in MZT pregnancies compared to ICSI (11.4%, 8.5%), PGT (22.7%, 16.6%) and TESA (20%, 13.3%). The total rate of twin-to-twin transfusion syndrome (TTTS) in MZTs was 2.7% (5/187); however, the TESA group had the highest rate at 20% and was significantly higher than the PGT group (p = 0.005). The four ART groups had no significant effect on the occurrence of congenital abnormalities or other neonatal outcomes in newborns from MZT pregnancies. Multivariate logistic regression analysis revealed that infertility duration, cause of infertility, the total dose of Gn used, history of miscarriages, and the number of miscarriages were not related to the risk of pregnancy loss (p > 0.05).

CONCLUSIONS

The rate of MZTs was similar among the four ART groups. The pregnancy loss and the early miscarriage rate of MZTs was increased in IVF patients. Neither the cause of infertility nor the history of miscarriage was correlated with the risk of pregnancy loss. MZTs in the TESA group had a higher risk of TTTS, placental effects influenced by sperm and paternally expressed genes may play a role. However, due to the small total number, studies with larger sample sizes are still needed to validate these result. Pregnancy and neonatal outcomes of MZTs after PGT treatment seem to be reassuring but the duration of the study was short, and long-term follow-up of the children is needed.

Comparison of Prenatal and Neonatal Outcomes of Selective Fetal Growth Restriction in Monochorionic Twin Pregnancies with or Without Twin-to-Twin Transfusion Syndrome After Radiofrequency Ablation

BACKGROUND

This study aimed to investigate and compare the prenatal and neonatal outcomes of monochorionic twin pregnancies complicated with fetal growth restriction (sFGR) with or without twin-to-twin transfusion syndrome (TTTS) after cord occlusion by radiofrequency ablation (RFA).

METHODS

This prospective cross-sectional study was conducted in women with monochorionic twin pregnancies of 16 to 26 weeks of gestational age (GA) in an academic hospital from 2016 to 2020. Demographic and obstetrical characteristics such as cervical length, GA of RFA and delivery, amnioreduction, cesarean section (C/S) rate, and maximum vertical pocket as well as prenatal, neonatal, and maternal outcomes were evaluated and compared between groups using Statistical Package for the Social Sciences (SPSS). Mann-Whitney U test or independent t test was used for quantitative data and Chi square test was applied for comparing qualitative variables. The significance level of tests was 0.05.

RESULTS

Totally 213 (106 sFGR and 107 TTTS+sFGR) cases were enrolled. The mean of maternal age (P=0.787), body mass index (P=0.932), gestational age at RFA (P=0.265), as well as gestational age of delivery (P=0.482), and C/S rate (P=0.124) were not significant between the two groups, but a significant difference (P<0.001) in cervical length was observed between the two groups. No significant differences were found in newborn and fetal outcomes such as fetal demise (P=0.827), PPROM (P=0.233), abortion (P=0.088), and admission to intensive care unit (P=0.822) between the groups.

CONCLUSION

Although worse fetal and neonatal outcomes were expected in the TTTS+sFGR group after RFA, no significant difference was observed between groups.

Are there differences between monochorionic twin placentas after spontaneous and assisted conception?

INTRODUCTION

No data are available on the placental characteristics of monochorionic twin pregnancies conceived by in vitro fertilization (IVF). This study investigates the differences between placentas from monochorionic diamniotic (MCDA) twin pregnancies conceived spontaneously and those conceived after IVF.

METHODS

This is a retrospective analysis of placental data from a consecutive series of MCDA twin pregnancies followed from the first trimester. The following placental characteristics were compared between IVF versus spontaneous MCDA pregnancies: placental sharing and birth weight discordance relative to placental sharing, the placental angioarchitecture (number, type, and size of anastomoses), and the umbilical cord insertion types.

RESULTS

Of the 256 MCDA placentas included in this analysis, 32 (12%) were conceived through IVF and 224 (88%) spontaneously. MCDA twin placentas after IVF did not differ significantly from MCDA twin placentas after spontaneous conception regarding placental sharing, birthweight discordance relative to sharing discordance, and angioarchitecture. There was a trend toward more discordant cord insertions (combination eccentric and velamentous) in IVF (25%) than in spontaneously conceived placentas (12%) (P = 0.05).

DISCUSSION

No differences could be demonstrated between MCDA placentation after spontaneous conception and IVF. Any differences in pregnancy outcome between spontaneous and IVF conceived MCDA twins may not be related to differences in placental sharing, angioarchitecture and cord insertion type.

Comparison of outcomes of monochorionic twin pregnancies conceived by assisted reproductive technology vs. spontaneous conceptions: A systematic review and meta-analysis

BACKGROUND

This review aimed to assess if monochorionic twin pregnancies conceived by assisted conception have worse maternal and neonatal outcomes as compared to those conceived naturally.

METHODS

Datasets of PubMed, ScienceDirect, CENTRAL, Embase, and Google Scholar were searched for studies comparing maternal and neonatal outcomes of monochorionic twin pregnancies conceived by assisted vs. spontaneous methods.

RESULTS

Eight studies comparing 337 assisted with 2,711 spontaneously conceived monochorionic twin pregnancies were included. Meta-analysis revealed that the mode of conception of monochorionic twin pregnancies had no impact on the risk of hypertensive disorders of pregnancy (HDP) (OR: 1.36 95% CI, 0.73, 2.54 I ² = 9% p = 0.03), twin-twin transfusion syndrome (TTTS) (OR: 0.83 95% CI, 0.52, 1.31 I ² = 0% p = 0.42), and very preterm delivery (OR: 1.18 95% CI, 0.74, 1.88 I ² = 41% p = 0.49). We noted no statistically significant difference in the mean birth weights (MD: -17.66 95% CI, -157.23, 121.91 I ² = 82% p = 0.80), risk of intra-uterine death (OR: 0.90 95% CI, 0.51, 1.60 I ² = 36% p = 0.73) and small for gestational age between the two groups (OR: 0.92 95% CI, 0.67, 1.26 I ² = 0% p = 0.59). There was an increased risk of caesarean sections (OR: 1.34 95% CI, 1.00, 1.80 I ² = 0% p = 0.05) and neonatal death with assisted conceptions as compared to spontaneous conceptions (OR: 2.35 95% CI, 1.11, 5.01 I ² = 37% p = 0.03).

CONCLUSION

Monochorionic twin pregnancies conceived via assisted reproductive technology have a heightened risk of cesarean section and neonatal deaths. However, there is a need for further studies to supplement current evidence.Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=325133, identifier: CRD42022325133.

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

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Study for risks of amniocentesis in anterior placenta compared to placenta of other locations

OBJECTIVE

This study aimed to compare the risks of amniocentesis between anteriorly located placentas and placentas in other locations and assess the factors that cause procedure-related complications.

MATERIALS AND METHODS

We prospectively studied women with singleton pregnancies who underwent amniocentesis between 2014 and 2020. The amniocentesis puncture sites were determined using ultrasonography. Women were classified into two groups according to their placental location. Medical records were retrospectively reviewed and characteristics and complications were compared between the groups of patients with different placental locations.

RESULTS

During the study period, 629 women underwent amniocentesis. Three cases (0.5%) of premature rupture of membranes and one case (0.3%) of fetal loss within four weeks of amniocentesis were found. Puncture failure was observed in 14 cases (2.2%). Puncture failure included procedures with failure to obtain an adequate sample and procedures requiring more than three needle insertions. There was no significant difference in the frequency of puncture failure between the two groups. Logistic regression analysis revealed that uterine myoma (odds ratio [OR] 11.92; 95% CI, 3.04-45.17) and tenting membrane (OR 33.57; 95% CI, 6.45-178.41) were associated with puncture failure.

CONCLUSION

Anteriorly located placenta is not a risk factor for amniocentesis-related adverse outcomes. Instead, puncture failure frequently occurs in case of uterine myoma and tenting membrane. If puncture failure occurs, or if the puncture is difficult to perform, then the procedure should be considered technically difficult and postponed until it can be more easily performed.

Serratia marcescens as a cause of unfavorable outcome in the twin pregnancy

Several Serratia species are widely distributed in nature, but Serratia marcescens is the only species frequently isolated in hospitals. This pathogen is mainly responsible for nosocomial infection, mostly in immunocompromised hosts. A 26-year-old woman with a twin pregnancy, regularly controlled, was hospitalized at 24 + 5 weeks of gestation due to scant vaginal bleeding, lower abdominal pain, and body temperature up to 37.5°C. Gynecological examination revealed bleeding accompanied by dilatation of the cervix. The laboratory analyses revealed leukocytosis with elevated C-reactive protein (CRP). Treatment was initiated with intravenous antibiotic administration. After admission, fetal membranes spontaneously ruptured, and an extremely preterm dichorionic female twin birth occurred at 25 + 0 weeks of gestation. Both infants died two days after labor. Pathological and microbiological analyses revealed chorioamnionitis caused by S. marcescens. According to the antibiogram, antibiotic treatment was continued for the next 7 days. The examination of cervical and vaginal discharge samples was negative three days and two weeks after therapy. S. marcescens may cause spontaneous miscarriages and, in this important case, caused loss of discordant twins in an extremely preterm birth by an immunocompetent patient. Infection by S. marcescens cannot be excluded as a cause of discordant growth and needs to be confirmed by further research.

Monochorionic twins after in-vitro fertilization: do they have poorer outcomes?

OBJECTIVE

To compare the outcome of monochorionic diamniotic (MCDA) twin pregnancies conceived by in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) with that of spontaneously conceived MCDA twins.

METHODS

This was a retrospective cohort study of MCDA twin pregnancies conceived after IVF/ICSI or spontaneously, followed from the first trimester onwards at a single center between January 2002 and September 2018. The primary outcome was survival per fetus from the first trimester until 28 days after birth. Secondary outcome measures were number of survivors, miscarriage, termination of pregnancy, intrauterine and neonatal death, major congenital anomalies, twin-twin transfusion syndrome, selective fetal growth restriction, gestational age at birth, delivery before 32 weeks' gestation, mode of delivery, admission to the neonatal intensive care unit, birth weight and birth-weight discordance.

RESULTS

Of the 654 MCDA pregnancies included in the analysis, 80 were conceived by IVF/ICSI and 574 spontaneously. Overall fetal and neonatal survival was significantly lower in the IVF/ICSI group than in the spontaneous-conception group (79% vs 90%; P = 0.001). In the IVF/ICSI group, compared with the spontaneous-conception group, loss of one or both twins occurred twice as often (29% vs 14%; P = 0.001) and there was a higher risk of second-trimester miscarriage (8% vs 1%; P = 0.002).

CONCLUSIONS

MCDA twins conceived after IVF/ICSI have lower overall survival rates and higher rates of second-trimester miscarriage than do spontaneously conceived MCDA twins. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Microwave ablation versus radiofrequency ablation for the treatment of severe complicated monochorionic pregnancies in China：protocol for a pilot randomised controlled trial

INTRODUCTION

Complicated monochorionic twin pregnancies are often associated with high perinatal morbidity and mortality, some of which are severe enough to require a gestational reduction surgery to improve fetal survival and reduce disabilities. While radiofrequency ablation is currently the most commonly used procedure with higher fetal survival and fewer maternal and fetal complications compared with other surgical methods, the therapeutic effect of microwave ablation (MWA) is reported to be better, presumably due to the higher thermal effect and fewer restrictions. Currently there is limited evidence to prove the feasibility of MWA for selective reduction. The aim of this pilot study is to explore the feasibility, efficacy and safety of MWA reduction for severe complicated monochorionic pregnancies and may provide evidence for using the MWA in intrauterine surgeries extensively.

METHODS AND ANALYSIS

This is a study protocol for a parallel-design pilot randomised controlled trial. 60 eligible patients with severe complicated monochorionic pregnancies will be randomised in a ratio of 1:1 to MWA group and radiofrequency group. Patients will be followed up until 6 months of age of the retained fetal. The primary analysis will compare the rates of neonatal survival at 28 days to evaluate the effect of MWA. The study will also evaluate the safety profile of MWA including the occurrence of postoperative adverse events and maternal and fetal complications. Additional secondary outcomes to be explored include the condition of neonatal asphyxia and the growth of surviving fetus at 6 months. Outcomes will be analysed by both a frequentist and the Bayesian statistical approach.

ETHICS AND DISSEMINATION

This study was approved by the ethical review committee of the Peking University Third Hospital (Beijing, China). The results of this study will be published in peer-reviewed scientific journals and presented at relevant academic conferences.

TRIAL REGISTRATION NUMBER

NCT04014452; Pre-results.

The risk of preterm birth in vanishing twin: A multicenter prospective cohort study

Objective

To evaluate not only the risk of total preterm birth (PTB) but also spontaneous preterm birth (sPTB) and indicated preterm birth (iPTB) in vanishing twin (VT).

Study design

This is a secondary analysis of a multicenter prospective cohort study. In 12 different healthcare institutions, women with singleton pregnancies were enrolled in early pregnancy and followed up till delivery.

Results

A total of 4,746 women were included in the final analysis, and. the frequency of VT was 1.1% (54/4746). VT group had a higher risk for total PTB (PTB<34 weeks, 2.1% vs. 14.8%, p<0.001; PTB<32 weeks, 1.6% vs. 13.0%, p<0.001; PTB<28 weeks, 0.9% vs. 13.0%, p<0.001) than singleton group. The VT group had increased risk for both sPTB and iPTB (<34 weeks, <32 weeks, and <28 weeks), and this increased risk for sPTB and iPTB in VT group remained significant even after controlling for confounders such as maternal age, parity, pre-pregnancy BMI, and mode of conception.

Conclusion

Vanishing twin can be an independent risk factor for both sPTB and iPTB when compared with singleton pregnancy.

Monochorionic diamniotic twins: What do I tell the prospective parents?

Monochorionic diamniotic twins occur in about 1 in 300 pregnancies. Compared with dichorionic twins, they face increased risks because of the shared circulation. In about 15%, an imbalance in blood exchange occurs, such as twin-twin transfusion syndrome and twin anemia polycythemia sequence. In this review, we summarize the latest evidence on the management of monochorionic diamniotic twin pregnancies and their specific complications, with a focus on information that is relevant for prospective parents.

Associated perinatal determinants of vanishing twin pregnancies achieved by in vitro fertilization vs. spontaneous conception

PURPOSE

To evaluate whether vanishing twin (VT) pregnancies following spontaneous conception have a more adverse perinatal outcome than those conceived after assisted reproduction techniques.

METHODS

The retrospective cohort study consisted of 316 VT pregnancies derived from a hospital database between January 1994 and January 2016 (81 after IVF/ICSI and 235 after spontaneous conception).

RESULTS

VT was significantly more prevalent after spontaneous conception (in 22.0% of twins) than after IVF/ICSI (in 14.5% of twins). VT pregnancies were significantly more associated with pre-gestational and gestational diabetes mellitus (GDM) in IVF/ICSI pregnancies compared to those spontaneously conceived [adjusted odds ratio (AOR): 4.12 and 11.1, respectively]. IVF-related placental insertion abnormalities were significantly higher in VT pregnancies. A high risk for VT was recorded in the spontaneous group for those who had previously undergone an induced abortion (AOR 0.56) or second-trimester fetal loss (AOR 0.67). The VT phenomenon was a major prognosticator of intrauterine growth retardation (IUGR) for the remaining fetus in IVF pregnancies (AOR 5.12). After controlling for covariates conjointly, advanced age (AOR 1.3), GDM (AOR 2.1), hypertensive disorders (AOR 3.5), primiparity (AOR 3.8), and placentation anomalies all represented independent risk factors for VT in IVF pregnancies.

CONCLUSIONS

IVF/ICSI poses a higher risk for an adverse perinatal outcome following VT pregnancies as compared with those spontaneously conceived.

Outcome of twin pregnancy with two live fetuses at 11-13 weeks' gestation

OBJECTIVES

To report and compare pregnancy outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies with two live fetuses at 11-13 weeks' gestation and to examine the impact of endoscopic laser surgery for severe twin-twin transfusion syndrome (TTTS) and/or selective fetal growth restriction (sFGR) on the outcome of MCDA twins.

METHODS

This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major abnormalities, we compared overall survival, fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks, delivery at < 37 and < 32 weeks, and birth weight < 5^th percentile between DC, MCDA and MCMA twins.

RESULTS

The study population of 6225 twin pregnancies with two live fetuses at 11-13 weeks' gestation with no major abnormalities included 4896 (78.7%) DC, 1274 (20.5%) MCDA and 55 (0.9%) MCMA twins. In DC twins, the rate of loss at < 24 weeks' gestation in all fetuses was 2.3%; this rate was higher in MCDA twins (7.7%; relative risk (RR), 3.258; 95% CI, 2.706-3.923) and more so in MCMA twins (21.8%; RR, 9.289; 95% CI, 6.377-13.530). In DC twins, the rate of perinatal death at ≥ 24 weeks in all twins that were alive at 24 weeks was 1.0%; this rate was higher in MCDA twins (2.5%; RR, 2.456; 95% CI, 1.779-3.389) and more so in MCMA twins (9.3%; RR, 9.130; 95% CI, 4.584-18.184). In DC twins, the rate of preterm birth at < 37 weeks' gestation in pregnancies with at least one liveborn twin was 48.6%; this rate was higher in MCDA twins (88.5%; RR, 1.824; 95% CI, 1.760-1.890) and more so in MCMA twins (100%; RR, 2.060; 95% CI, 2.000-2.121). In DC twins, the rate of preterm birth at < 32 weeks was 7.4%; this rate was higher in MCDA twins (14.2%; RR, 1.920; 95% CI, 1.616-2.281) and more so in MCMA twins (26.8%; RR, 3.637; 95% CI, 2.172-6.089). In DC twin pregnancies with at least one liveborn twin, the rate of a small-for-gestational-age neonate among all liveborn twins was 31.2% and in MCDA twins this rate was higher (37.8%; RR, 1.209; 95% CI, 1.138-1.284); in MCMA twins, the rate was not significantly different (33.3%; RR, 1.067; 95% CI, 0.783-1.455). Kaplan-Meier analysis showed a significant difference in survival in MCDA and MCMA twins, compared to DC twins, for both the interval of 12 to < 24 weeks' gestation (log-rank test, P < 0.0001 for both) and that of ≥ 24 to 38 weeks (log-rank test, P < 0.0001 for both). Endoscopic laser ablation of intertwin communicating placental vessels was carried out in 127 (10.0%) MCDA twin pregnancies for TTTS and/or sFGR and, in 111 of these, surgery was performed at < 24 weeks; both fetuses survived in 62 (55.9%) cases, one fetus survived in 25 (22.5%) cases and there were no survivors in 24 (21.6%) cases. On the extreme assumption that, had laser surgery not been carried out in these cases, all fetuses would have died, the total fetal loss rate at < 24 weeks' gestation in MCDA twins would have been 13.5%.

CONCLUSIONS

The rates of fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks and preterm birth are higher in MCDA and more so in MCMA twins than in DC twins. In MCDA twins, the rate of fetal loss may have been reduced by endoscopic laser surgery in those that developed early TTTS and/or sFGR. These data would be useful in counseling parents as to the likely outcome of their pregnancy and in defining strategies for surveillance and interventions in the management of the different types of twin pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Perinatal mortality, timing of delivery and prenatal management of monoamniotic twin pregnancy: systematic review and meta-analysis

OBJECTIVE

To quantify the rate of perinatal mortality in monochorionic monoamniotic (MCMA) twin pregnancies, according to gestational age, and to ascertain the incidence of mortality in pregnancies managed as inpatients compared with those managed as outpatients.

METHODS

MEDLINE, EMBASE and CINAHL databases were searched for studies on monoamniotic twin pregnancy. The primary outcomes explored were the incidence of intrauterine death (IUD), neonatal death (NND) and perinatal death (PND) in MCMA twins at different gestational-age windows (24-30, 31-32, 33-34, 35-36 and ≥ 37 weeks of gestation). The secondary outcomes were the incidence of IUD, NND and PND in MCMA twins according to the type of fetal monitoring (inpatient vs outpatient), and the incidence of delivery ahead of schedule. Random-effects model meta-analyses were used to analyze the data.

RESULTS

Twenty-five studies (1628 non-anomalous twins reaching 24 weeks of gestation) were included. Single and double intrauterine deaths occurred in 2.5% (95% CI, 1.8-3.3%) and 3.8% (95% CI, 2.5-5.3%) of cases, respectively. IUD occurred in 4.3% (95% CI, 2.8-6.2%) of twins at 24-30 weeks, in 1.0% (95% CI, 0.6-1.7%) at 31-32 weeks and in 2.2% (95% CI, 0.9-3.9%) at 33-34 weeks of gestation, while there was no case of IUD, either single or double, from 35 weeks of gestation. In MCMA twin pregnancies managed mainly as inpatients, the incidence of IUD was 3.0% (95% CI, 1.4-5.2%), while the corresponding figure for those managed mainly as outpatients was 7.4% (95% CI, 4.4-11.1%). Finally, 37.8% (95% CI, 28.0-48.2%) of MCMA pregnancies were delivered before the scheduled time, due mainly to spontaneous preterm labor or abnormal cardiotocographic findings.

CONCLUSIONS

MCMA twins are at high risk of perinatal loss during the third trimester of pregnancy, with the large majority of such losses occurring as apparently unexpected events. Inpatient management seems to be associated with a lower rate of mortality, although further studies are needed in order to establish the appropriate type and timing of prenatal assessment in these pregnancies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Development and evaluating multimarker models for guiding treatment decisions

Background

Despite the growing interest in developing markers for predicting treatment response and optimizing treatment decisions, an appropriate methodology to identify, combine and evaluate such markers has been slow to develop. We propose a step-by-step strategy for analysing data from existing randomised trials with the aim of identifying a multi-marker model for guiding decisions about treatment.

Methods

We start with formulating the treatment selection problem, continue with defining the treatment threshold, prepare a list of candidate markers, develop the model, apply the model to estimate individual treatment effects, and evaluate model performance in the study group of patients who meet the trial eligibility criteria. In this process, we rely on some well-known techniques for multivariable prediction modelling, but focus on predicting benefit from treatment, rather than outcome itself. We present our approach using data from a randomised trial in which 808 women with multiple pregnancy were assigned to cervical pessary or control, to prevent adverse perinatal outcomes. Overall, cervical pessary did not reduce the risk of adverse perinatal outcomes.

Results

The treatment threshold was zero. We had a preselected list of 5 potential markers and developed a logistic model including the markers, treatment and all marker-by-treatment interaction terms. The model was well calibrated and identified 35% (95% confidence interval (CI) 32 to 39%) of the trial participants as benefitting from pessary insertion. We estimated that the risk of adverse outcome could be reduced from 13.5 to 8.1% (5.4% risk reduction; 95% CI 2.1 to 8.6%) through model-based selective pessary insertion. The next step is external validation upon existence of independent trial data.

Conclusions

We suggest revisiting existing trials data to explore whether differences in treatment benefit can be explained by differences in baseline characteristics of patients. This could lead to treatment selection tools which, after validation in comparable existing trials, can be introduced into clinical practice for guiding treatment decisions in future patients.

The Vanishing Twin Syndrome: Two Cases of Extreme Malformations Associated With Vanished Twins

Two cases of devastating fetal malformations associated with vanished monochorionic twins were identified upon review of pathology files. A 35-year-old G1P0 woman and 36-year-old G3P1 woman were both diagnosed with an intrauterine twin gestation via transvaginal ultrasound at 10 weeks. The spectrum of fetal anomalies ranged from omphalocele, bilateral upper extremity, and unilateral lower extremity hypoplasia, to craniofacial malformation with diaphragmatic hernia. On histopathologic examination, the placentas demonstrated vascular anastomoses between the surviving co-twin and the "vanished" fetal sac. We propose anastomotic placental vasculature as a contributing factor to the observed fetal malformations. Additionally, genetic or teratogenic factors may have been attributed to the demise of the first twin and the anomalies seen in the other twin. While such instances are rare, they are important to consider when counseling patients regarding outcomes associated with a monochorionic vanished twin.

Developmental and behavioral outcomes of uncomplicated monochorionic diamniotic twins born in the third trimester

BACKGROUND

Relatively little is known about the neurodevelopmental and behavioral outcomes of monochorionic diamniotic (MCDA) twin pregnancies where there are no antenatal complications peculiar to monochorionicity or prematurity.

METHODS

Twenty-two MCDA twins (44 children) with an average age of 4.3 years, and with no antenatal complications detected by 28 weeks of gestation, were recruited from a feto-maternal unit database. Parents completed a battery of neurodevelopmental and behavioral assessment questionnaires.

RESULTS

Eighteen children (41%) were identified as having developmental or behavioral concerns, predominantly of mild severity, which in turn were associated with a lower birth weight of medium effect size (Cohen's d=0.59).

CONCLUSION

MCDA twins delivered in the third trimester with no antenatal monochorionic complications in the first two trimesters appear to be at risk for subtle neurodevelopmental difficulties, associated with a lower birth weight. Ongoing developmental surveillance of these children during preschool-age is indicated for early identification and intervention.

Outcome of monochorionic-biamniotic twins conceived by assisted reproduction: a population-based study

Objecive: To evaluate the perinatal outcome of monochorionic-diamniotic twins conceived by assisted reproduction technology (ART).

METHODS

We compared data from a national population-based perinatal registry on perinatal outcomes of monochorionic-diamniotic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic-diamniotic twins. We compared maternal characteristics, pregnancy complications and perinatal outcomes.

RESULTS

Monochorionic-diamniotic twin pregnancies (n=45) comprised 5.5% of all ART twins, and 9.3% of all monochorionic twins in this dataset. ART does not appear to increase the already high risk of monochorionicity compared to spontaneous conception, with the latter having an increased incidence for birth weight <1500 g [odds ratio (OD) 2.6, 95% confidence interval (CI) 1.2-5.4].

CONCLUSION

Our results disagree with hospital-based data and suggest that monochorionic-diamniotic twins following ART are not at increased risk of adverse perinatal outcomes compared to spontaneous monochorionic-diamniotic twins as well as to dichorionc twins conceived by ART.

A multivariable model to guide the decision for pessary placement to prevent preterm birth in women with a multiple pregnancy: a secondary analysis of the ProTWIN trial

OBJECTIVE

The ProTWIN Trial (NTR1858) showed that, in women with a multiple pregnancy and a cervical length < 25(th) percentile (38 mm), prophylactic use of a cervical pessary reduced the risk of adverse perinatal outcome. We investigated whether other maternal or pregnancy characteristics collected at baseline can improve identification of women most likely to benefit from pessary placement.

METHODS

ProTWIN is a multicenter randomized trial in which 808 women with a multiple pregnancy were assigned to pessary or control. Using these data we developed a multivariable logistic model comprising treatment, cervical length, chorionicity, pregnancy history and number of fetuses, and the interaction of these variables with treatment as predictors of adverse perinatal outcome.

RESULTS

Short cervix, monochorionicity and nulliparity were predictive factors for a benefit from pessary insertion. History of previous preterm birth and triplet pregnancy were predictive factors of possible harm from pessary. The model identified 35% of women as benefiting (95% CI, 32-39%), which is 10% more than using cervical length only (25%) for pessary decisions. The model had acceptable calibration. We estimated that using the model to guide the choice of pessary placement would reduce the risk of adverse perinatal outcome significantly from 13.5% when no pessary is inserted to 8.1% (absolute risk reduction, 5.4% (95% CI, 2.1-8.6%)).

CONCLUSIONS

We developed and internally validated a multivariable treatment selection model, with cervical length, chorionicity, pregnancy history and number of fetuses. If externally validated, it could be used to identify women with a twin pregnancy who would benefit from a pessary, and lead to a reduction in adverse perinatal outcomes in these women. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Severe acute maternal morbidity in multiple pregnancies: a nationwide cohort study

BACKGROUND

Adverse neonatal outcomes in multiple pregnancies have been documented extensively, in particular those associated with the increased risk of preterm birth. Paradoxically, much less is known about adverse maternal events. The combined risk of severe acute maternal morbidity in multiple pregnancies has not been documented previously in any nationwide prospective study.

OBJECTIVE

The objective of the study was to assess the risk of severe acute maternal morbidity in multiple pregnancies in a high-income European country and identify possible risk indicators.

STUDY DESIGN

In a population-based cohort study including all 98 hospitals with a maternity unit in The Netherlands, pregnant women with severe acute maternal morbidity were included in the period Aug. 1, 2004, until Aug. 1, 2006. We calculated the incidence of severe acute maternal morbidity in multiple pregnancies in The Netherlands using The Netherlands Perinatal Registry. Relative risks (RR) of severe acute maternal morbidity in multiple pregnancies compared with singletons were calculated. To identify possible risk indicators, we also compared age, parity, method of conception, onset of labor, and mode of delivery for multiple pregnancies using The Netherlands Perinatal Registry as reference.

RESULTS

A total of 2552 cases of severe acute maternal morbidity were reported during the 2 year study period. Among 202 multiple pregnancies (8.0%), there were 197 twins (7.8%) and 5 triplets (0.2%). The overall incidence of severe acute maternal morbidity was 7.0 per 1000 deliveries and 6.5 and 28.0 per 1000 for singletons and multiple pregnancies, respectively. The relative risk of severe acute maternal morbidity compared with singleton pregnancies was 4.3 (95% confidence interval [CI], 3.7-5.0) and increased to 6.2 (95% CI 2.5-15.3) in triplet pregnancies. Risk indicators for developing severe acute maternal morbidity in women with multiple pregnancies were age of ≥ 40 years, (RR, 2.5 95% CI, 1.4-4.3), nulliparity (RR, 1.8, 95% CI, 1.4-2.4), use of assisted reproductive techniques (RR, 1.9, 95% CI, 1.4-2.5), and nonspontaneous onset of delivery (RR, 1.6, 95% CI, 1.2-2.1). No significant difference was found between mono- and dichorionic twins (RR, 0.8, 95% CI, 0.6-1.2).

CONCLUSION

Women with multiple pregnancies in The Netherlands have a more than 4 times elevated risk of sustaining severe acute maternal morbidity as compared with singletons.

Prenatal diagnosis of thalassemia in twin pregnancies in mainland China

The aim of this study was to describe our experience with prenatal diagnosis of thalassemia in twin pregnancies at a tertiary referral centre in mainland China. All cases of twin pregnancies at risk of α- or β-thalassemias were followed over an eight-year period. There were 32 twin pregnancies at a mean gestation of 14 weeks (range, 11-21 weeks) at risk of thalassemias, including 19 at risk of α-thalassemia and 13 at risk of β-thalassemia. Chorionicity was determined by ultrasound before prenatal diagnosis. In 19 twin pregnancies at risk of α-thalassemia, there were four where both foetuses were affected, 13 where both foetuses were not affected, and two where one foetus was affected and the other one was not affected. In 13 twin pregnancies at risk of β-thalassemia, there were five where both foetuses were affected, six where both foetuses were not affected, and two where one foetus was affected and the other one was not affected. The pregnancies with two affected foetuses were aborted (including four affected by α-thalassemia and five affected by β-thalassemia), and in pregnancies with one normal twin and one affected twin, the affected foetuses were selectively aborted (including two twins affected by α-thalassemia, and two twins affected by β-thalassemia). Efforts should be taken to reduce the risks of the mother and foetuses in prenatal diagnosis without compromising the precise diagnosis.

Risk of Monozygotic Twins After Assisted Reproduction: A Population-Based Approach

BACKGROUND

Recent studies have suggested that ovarian stimulation and assisted reproductive techniques (ART) may increase the frequency of monozygotic twins. In this article, we present the analysis of the estimated frequency of twin deliveries following in vitro fertilization (IVF) in Lombardy during the period 2010-2014 for a total of 450,949 pregnancies.

METHOD

This is a population-based study using data from the regional data base of Lombardy, a northern Italian region with a population of about 10 million inhabitants. During the considered period, a total of 461,424 single or multiple births were registered in Lombardy. After exclusion of triplets or more pregnancies, the total number of twin deliveries, in separate strata of like and unlike sex pregnancies twin deliveries, were obtained and the rate of twin deliveries was computed according to spontaneous and non-spontaneous conception and type of ART. Further, estimates of dizygotic or monozygotic twin births were calculated using Weinberg's methods.

RESULTS

The frequency of twins deliveries was 1.24/100 deliveries after natural conception and 20.05 after assisted conception. The estimated rates of monozygotic twins was 0.45 and 0.72/100 (95% CI: 0.58-0.91) deliveries after natural and assisted conception, respectively. This difference was statistically significant (p < .05).

CONCLUSION

the present population based study suggests that the risk of monozygotic twin is about 60% higher among assisted than after natural conception.

Estimating the Risk of Monochorionic Twins in IVF Pregnancies From the Perspective of a Prenatal Diagnosis Unit

The aim of the present work was to estimate the risk of monochorionic twin (MCT) pregnancies in in vitro fertilization (IVF) cycles using data from a prenatal diagnosis unit. This was a retrospective cross-sectional study reporting on the frequency of IVF pregnancies among women attending a prenatal diagnosis service specifically dedicated to the management of monochorionic pregnancies. The observed rate was compared with the local regional rate of IVF births (2.2%). A binomial distribution model was used to calculate the 95% CI of proportions. One hundred and forty-five monochorionic pregnancies were selected. Ten of these were achieved with IVF, corresponding to a rate of 6.9% (95% CI: 3.5–11.8), significantly higher than the background rate in the local population of 2.2%. When considering exclusively monochorionic pregnancies achieving delivery of two viable newborns (n = 132), the number of IVF pregnancies was nine (6.8%, 95% CI: 3.7–12.5). We did not detect major differences in pregnancy outcome between IVF and natural monochorionic pregnancies, with the exception of the proportion of newborns with a neonatal birth < 2,500 g (100% vs. 80%, p = .03). In conclusion, data obtained from the perspective of a prenatal diagnosis unit suggest that women undergoing IVF face a 3- to 4-fold increased risk of monochorionic pregnancies.

Outcome of monochorionic twins conceived by assisted reproduction

OBJECTIVE

To evaluate monochorionic twins conceived by assisted reproductive technology (ART).

DESIGN

We compared perinatal outcomes of monochorionic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic twins.

SETTING

Referral center.

PATIENT(S)

Mothers to monochorionic and dichorionic twins conceived by ART and spontaneous monochorionic twins.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Maternal characteristics, pregnancy complications, and perinatal outcomes.

RESULT(S)

Monochorionic twin pregnancies (n = 25) comprise 7.2% of all ART twins and 4.9% of all monochorionic twins in this data set. Monochorionic pairs have a significantly worse outcome compared with dichorionic sets in terms of lower gestational age and birth weight. ART appears to increase the already high risk of monochorionicity compared with spontaneous conception: odds ratio (OR), 2.9 (1.1-7.3) for preterm birth at <32 weeks and OR, 5.9 (2.5-1.49) for birth weight <1,500 g.

CONCLUSION(S)

Monochorionic twins after ART are at increased risk of adverse perinatal outcomes compared with spontaneous monochorionic twins and with dichorionic twins conceived by ART.

Screening and Invasive Testing in Twins

Prenatal screening and testing for trisomy 21 in twin pregnancies poses a number of challenges: the exact estimate of the a priori risk of trisomy 21, the choice of prenatal screening test and/or invasive techniques to employ for the diagnosis and the impact of the result on the options of treatment in case of discordant results within a twin pair or among multiples. These different aspects are discussed below while recognizing that many issues remain unresolved.

Prenatal diagnosis in twin gestations

Twin gestations face an increased risk of structural abnormalities compared with singleton gestations, as well as an increased risk of aneuploidy. Accordingly, there is a need for accurate prenatal diagnosis of fetal genetic disorders and structural anomalies in twin gestations. Given the increased risk of congenital anomalies, a detailed sonographic survey of fetal anatomy is recommended in the early second trimester of twin gestations. In addition, fetal echocardiography should be considered in monochorionic twin gestations and in dichorionic twin pregnancies conceived using assisted reproductive technologies given the increased risk of congenital heart disease in these populations. Although first- and second-trimester aneuploidy screening in twin gestations is available, screening is less accurate than in singleton gestations. Invasive prenatal diagnosis in twin pregnancies is associated with a risk of pregnancy loss that is higher than the baseline risk of loss among twin gestations. Precise procedure-related loss rates in twin gestations undergoing chorionic villus sampling or amniocentesis, however, remain unclear because of methodological differences between published studies investigating diagnostic procedures in twins.

Amniocentesis in twin pregnancies: a systematic review of the literature

OBJECTIVE

Using published data, we sought to determine the amniocentesis-related loss rate in twin gestations.

METHODS

We searched the PUBMED database using keywords "amniocentesis", "twin" and "twins" to identify articles evaluating genetic amniocentesis in twin gestations published from January 1970 to December 2010. Random effects models were used to pool procedure-related loss rates from included studies.

RESULTS

The definition of "loss" varied across the 17 studies identified (Table 1). The pooled procedure-related loss rate at < 24 weeks was 3.5% (95% confidence interval [CI] 2.6-4.7) (Figure 2). Pooled loss rates at < 28 weeks (Figure 4) and to term (Figure 5) could not be calculated due to unacceptable heterogeneity of available data. Seven studies included a control (no amniocentesis) group and reported a pooled odds ratio for total pregnancy loss among cases of 1.8 (95% CI 1.2-2.7) (Figure 3). Only 1 study reported procedure-related loss rates by chorionicity (7.7% among monochorionics vs 1.4% among controls; p 0.02).

CONCLUSION

Analysis of published data demonstrated a pooled amniocentesis-related loss rate of 3.5% in twin gestations < 24 weeks. Pooled loss rates within other post-amniocentesis intervals or other gestational age windows and the impact of chorionicity on procedure-related loss rates cannot be determined from published data.

Prospective risk of late stillbirth in monochorionic twins: a regional cohort study

OBJECTIVE

Monochorionic (MC) pregnancies are routinely delivered electively at late preterm gestation with the aim of avoiding stillbirth at term. The aim of this study was to evaluate the prospective risk of late stillbirth in a large regional cohort of twin pregnancies of known chorionicity.

METHODS

This was a retrospective study of all twin pregnancy births of known chorionicity between 2000 and 2009 from a large regional cohort consisting of nine hospitals. Prospective risk was calculated per 1000 fetuses rather than pregnancies, as each twin pregnancy had two gestations at risk of stillbirth.

RESULTS

A total of 3005 twin pregnancies delivered after 26 weeks' gestation in the Southwest Thames Obstetric Research Collaborative. The total risk of stillbirth after 26 weeks in MC twins (19.1 per 1000 fetuses) was significantly higher than in dichorionic (DC) twins (6.5 per 1000 fetuses), with an odds ratio (OR) of 2.97 (95% CI, 1.71-5.18). The risk of stillbirth in MC twins did not change significantly between 26 weeks (1.8 per 1000 fetuses) and 36 weeks (3.4 per 1000 fetuses), with an OR of 1.85 (95% CI, 0.3-13.2). The equivalent figures for DC twins were 0.6 per 1000 fetuses and 2.1 per 1000 fetuses, respectively (OR, 3.4 (95% CI, 0.9-13.2)).

CONCLUSIONS

The risk of stillbirth in MC twins does not appear to increase significantly near term. This may be due to a policy of routine surveillance and elective delivery from 36 weeks. The data do not support a policy of elective delivery before 36 weeks' gestation in MC pregnancies.

Influence of chorionicity on perinatal outcome in a large cohort of Danish twin pregnancies

OBJECTIVE

To assess outcome in twin pregnancies according to chorionicity.

METHODS

A cohort was retrieved from local ultrasound databases at 14 obstetric departments in Denmark, comprising all twin pregnancies with two live fetuses scanned between weeks 11 and 14 in the period 1 January 2004 to 31 December 2006. Outcome data were retrieved from the National Board of Health.

RESULTS

Among 2038 twin pregnancies, 1757 (86.2%) were dichorionic (DC) and 281 (13.8%) were monochorionic diamniotic (MC). In MC pregnancies, the rate of spontaneous fetal loss in both second and third trimesters was more than threefold higher than the comparable rate in DC pregnancies: 6.0% vs. 1.9% for at least one fetus in the second trimester (P < 0.001) and 2.1% vs. 0.7% in the third trimester (P = 0.03). In 98.4% of DC pregnancies and in 91.1% of MC pregnancies, at least one infant was liveborn. Amongst pregnancies with two live fetuses at 24 weeks, the proportion with two live infants at 28 days after delivery was 97.5% and 95.1%, respectively.

CONCLUSIONS

The increased incidence of fetal loss in MC pregnancies compared with DC pregnancies predominantly occurs before 24 weeks' gestation. After this stage, although the risk of intrauterine fetal death is still higher in MC than in DC pregnancies, if both fetuses are alive at 24 weeks, the chance of a woman having two live infants 1 month after delivery is similar in MC and DC pregnancies.

Neonatal outcome using ultrathin fetoscope for laser coagulation in twin-to-twin-transfusion syndrome

OBJECTIVE

To improve neonatal outcome using ultrathin fetoscope for laser treatment of twin-to-twin transfusion syndrome.

METHODS

Retrospective cohort study of a series of 80 cases of twin-to-twin-transfusion syndrome prior to 26-weeks' gestation subjected to laser coagulation by means of a 1.0/1.2 mm fiber fetoscope with a sheath sectional area 2.65 mm(2)/3.34 mm(2) (n=27) and a 2.0 mm classic lens fetoscope with a sheath sectional area: 6.63 mm(2)/11.27 mm(2) (n=53).

RESULTS

The survival rates of at least one twin in the compared groups were 94.4% (classic optic) and 100% (ultrathin optic), for both twins: 75.5% and 83.3%, respectively. By decreasing sheath diameter a pregnancy was prolonged by an average of 21.3 days (P=0.0045), with a resulting increase in the recipient's weight of 389 g (P=0.0049) and an increase in the donor's Apgar score. However, the intervention with ultrathin optic took 11 min longer (P=0.031).

CONCLUSION

The reduction of the iatrogenic damage of the amniotic membrane using ultrathin fetoscope with a small sheath, significantly improves the neonatal outcome after laser treatment of twin-to-twin-transfusion syndrome. The operator should only commence working with the 1 mm fetoscope after the learning curve has been accomplished.

Stillbirth and neonatal mortality in monochorionic and dichorionic twins: a population-based study

BACKGROUND

Chorionicity is one of the main predictors of higher perinatal mortality in twins. The aim of this large population-based study was to analyse stillbirth and neonatal mortality by cause of death and chorionicity and to quantify the risk of stillbirth by gestational age in dichorionic (DC) and monochorionic (MC) twins.

METHODS

We used data on twin maternities delivered in the North of England from 1998 to 2007 and notified to the Northern Survey of Twin and Multiple Pregnancy. Prospective risk of stillbirth by gestational age at death was calculated using number of stillborn fetuses at or beyond a given gestational period per 1000 fetuses in ongoing pregnancies.

RESULTS

There were 4565 twin maternities (9130 twins) with an overall twinning rate of 14.9 per 1000 maternities. The overall stillbirth and neonatal mortality rates in twins during 1998-2007 were 18.0/1000 births and 23.0/1000 live births, respectively. Stillbirth and neonatal mortality rates were significantly higher in MC than DC twins: 44.4 versus 12.2 per 1000 births [relative risk (RR): 3.6; 95% CI: 2.6-5.1], and 32.4 versus 21.4 per 1000 live births (RR: 1.5; 95% CI: 1.04-2.2), respectively. There was no significant improvement over time in either stillbirth or neonatal mortality rates in either group. The prospective risk of antepartum stillbirth was higher for MC than DC twins at all preterm gestations and the highest risk was before 28 weeks' gestation.

CONCLUSIONS

MC twins have higher rates of stillbirth and neonatal mortality than DC twins, and rates did not improve over 1998-2007. The prospective risk of antepartum stillbirth is much higher for MC twins at all gestational ages.

Monochorionic twin pregnancy: screening, pathogenesis of complications and management in the era of microinvasive fetal surgery

OBJECTIVE

The management of monochorionic (MC) twin pregnancies varies in different medical centers. This paper compares screening methods to predict the complications of the MC twin pregnancy and different treatment methods.

METHODS

We performed a literature search without language restriction in Cochrane library and PubMed (1970-2009). Case series and cohort screening studies, pathogenesis and management of complications of MC pregnancy were included.

RESULTS

Elevated risk for intrauterine fetal death (IUFD) and twin-to-twin transfusion syndrome (TTTS) can be detected sonographically. Monitoring of MC pregnancies at increased risk and regular training sessions for the operating team combined with reduced fetoscopic amniotic membrane damage increase fetal survival rate from laser coagulation to nearly 100% for at least one fetus and to 90% for both.

CONCLUSION

Monitoring of MC pregnancies at increased risk and laser treatment of TTTS in medical centers with sufficient experience might improve neonatal outcome.

The pregnancy and long-term neurodevelopmental outcome of monochorionic diamniotic twin gestations: a multicenter prospective cohort study from the first trimester onward

OBJECTIVES

We sought to document the pregnancy and neurodevelopmental outcome in monochorionic diamniotic twin pregnancies and to identify risk factors for death and impairment.

STUDY DESIGN

We conducted a prospective cohort study of 136 monochorionic twins followed up from the first trimester until infancy.

RESULTS

A total of 122 (90%) pregnancies resulted in 2 survivors, 6 (4%) in 1 survivor and 8 (6%) in no survivor. In all, 230 (92%) of 250 surviving infants were assessed at a mean age of 24 months. Neurodevelopmental impairment was present in 22 (10%) infants. Death or impairment of 1 or both infants occurred in 28 (22%) of 126 pregnancies. Twin-to-twin transfusion syndrome and assisted conception increased the risk of both death and impairment, whereas early-onset discordant growth only increased the risk of death.

CONCLUSION

The mortality in this prospective series was 8% and neurodevelopmental impairment occurred in 10% of infants.

Twin-to-twin transfusion syndrome: an antiangiogenic state?

OBJECTIVE

An imbalanced chronic blood flow between the donor and recipient twin through placental vascular anastomoses is the accepted pathophysiology of twin-to-twin transfusion syndrome (TTTS). Vascular endothelial growth factor receptor-1 (VEGFR-1) mRNA is overexpressed only in the syncytiotrophoblast of the donor twin in some cases of TTTS. This study was conducted to determine maternal plasma concentrations of placental growth factor (PlGF), soluble VEGFR-1, and soluble endoglin (s-Eng) in monochorionic-diamniotic pregnancies with and without TTTS.

STUDY DESIGN

This case-control study included monochorionic-diamniotic pregnancies between 16-26 weeks with and without TTTS. Maternal plasma concentrations of PlGF, sVEGFR-1, and s-Eng were determined with ELISA. A P value < .05 was considered statistically significant.

RESULTS

Patients with TTTS had higher median plasma concentrations of s-Eng (14.8 ng/mL vs 7.8 ng/mL; P < .001) and sVEGFR-1 (6383.1 pg/mL vs 3220.1 pg/mL; P < .001]; and lower median plasma concentrations of PlGF (115.5 pg/mL vs 359.3 pg/mL; P = .002) than those without TTTS.

CONCLUSION

We propose that an antiangiogenic state may be present in some cases of TTTS.

First-trimester ultrasound examination and the outcome of monochorionic twin pregnancies

OBJECTIVE

To refine the incidence of abnormal first-trimester ultrasound measurements and their correlation with the outcome of monochorionic diamniotic pregnancies.

METHODS

First-trimester crown-rump length (CRL) and nuchal translucency thickness (NT) measurements were studied in three subgroups of a total of 200 monochorionic twin gestations referred to our center between June 2002 and February 2006. Intertwin CRL discordance was defined as > 10% and the 95th percentile of NT thickness for gestational age was used. The first group of 103 consecutive unselected monochorionic diamniotic twin pregnancies was prospectively followed up from 11-14 weeks onwards, throughout the pregnancy. The second group of 136 nonconsecutive monochorionic diamniotic twin pregnancies including 64 that developed TTTS was studied retrospectively. The third group of 100 consecutive cases of TTTS studied retrospectively for the correlation between first trimester measurements and staging and timing of occurrence of TTTS.

RESULTS

In group 1, the incidence of TTTS was 5 in 103 (5%, 95CI [0.7-9]). Large intertwin CRL discordance and increased NT were correlated with perinatal death. In group 2, no significant association was found between first-trimester parameters and the development of TTTS but discordance in early second trimester biometry and Doppler were. In group three, a positive correlation was found between the intertwin discordance in CRL and early occurrence of TTTS before 20 weeks of gestation (p = 0.02).

CONCLUSION

Monochorionic twin gestations who ultimately develop TTTS may exhibit intertwin difference in growth as early as 11-14 weeks of gestation. The earlier the discordance the earlier the development of the disease.

Discordance in nuchal translucency thickness in the prediction of severe twin-to-twin transfusion syndrome

OBJECTIVE

To examine in monochorionic pregnancies the possible value of intertwin discordance in nuchal translucency (NT) thickness in the prediction of early fetal death or severe twin-twin transfusion syndrome (TTTS).

METHODS

In 512 monochorionic twin pregnancies NT was measured at 11 to 13 + 6 weeks' gestation and regression analysis was used to determine the significance of the association between the intertwin discordance in NT and subsequent early fetal death or development of severe TTTS requiring endoscopic laser surgery.

RESULTS

In 412 (80.5%) pregnancies there was a normal outcome, in 58 (11.3%) there was severe TTTS requiring endoscopic laser surgery at 18-24 weeks, in 19 (3.7%) there was death of one or both fetuses at 13-18 weeks and in 23 (4.5%) there was fetal death at 21-38 weeks. In the four outcome groups the median discordance in NT was 11%, 22%, 35% and 7%, respectively. Significant prediction of early fetal death and severe TTTS was provided by the discordance in fetal NT, which was not significantly improved by including the discordance in crown-rump length. If the discordance in NT was 20% or more, the false positive rate was 20%, the detection rate of early fetal death was 63% and the detection rate of severe TTTS was 52%.

CONCLUSIONS

Discordance in NT of 20% or more is found in about 25% of monochorionic twins and in this group the risk of early fetal death or development of severe TTTS is more than 30%. If the discordance is less than 20% the risk of complications is less than 10%.

Twin pregnancy possibly associated with high semen quality

BACKGROUND

Recent studies found an association between a long waiting time to pregnancy (TTP) and reduced probability of twinning and a reduced dizygotic (DZ) twinning rate in subfertile men. However, it remains unsolved whether semen quality is associated with twin offspring. We therefore studied the semen quality in a group of fathers of naturally conceived twins.

METHODS

In this study, 37 fathers of DZ twins and 15 fathers of monozygotic (MZ) twins participated, and 349 normal fertile men served as a reference group. All men delivered a semen sample, underwent a physical examination and completed a questionnaire.

RESULTS

After adjustment, fathers of DZ and MZ twins had 3.6 (95% CI 1.7; 5.4) and 4.6 (95% CI 2.0; 7.2) percentage points higher percentage of sperm cells with normal morphologic features and percentages of motile sperm cells were 11.5 (95% CI 7.2; 15.9) and 12.5 (95% CI 6.3; 18.6) percentage points higher than the reference group (P < 0.01). Fathers of DZ twins and MZ twins had 24.7 (95% CI; -9.1; 71.3) and 17.0% (-25.2%; 83.0%) higher sperm concentration than the reference group.

CONCLUSIONS

Fathers of DZ twins had a better semen quality than the reference group, which supports the assumption that spontaneous DZ twinning rate can be used as a sensor of male fecundity of a population.