Optimal timing of fetal reduction from twins to singleton: earlier the better or later the better?

Late selective termination in dichorionic twins: comparing late second and third trimester procedures

RESEARCH QUESTION

Do perinatal outcomes of selective termination performed in the late second versus third trimester differ and what risk factors are associated with subsequent preterm birth?

DESIGN

This is a retrospective cohort study of late selective terminations performed in dichorionic twins between 2009 and 2021. Perinatal outcomes were compared between two groups: group A, late second trimester (20.2 to 24.2 weeks, n = 26), and group B, third trimester (≥28.2 weeks, n = 55) selective terminations. Univariate and multivariate analyses were conducted to identify factors associated with post-procedure preterm birth.

RESULTS

In total, 81 dichorionic twin pregnancies were included. There were no pregnancy losses but 16% (13/81) of cases experienced complications. Group A had a higher median birthweight centile (36.5th versus 15th centile, P = 0.002) and lower rates of intrauterine growth restriction (IUGR) and Caesarean delivery (11.5% versus 32.7%, P = 0.04; and 26.9% versus 61.8%, P = 0.003) than group B. Preterm birth rates were similar (46.2% versus 63.6%, P = 0.15). Multiple regression revealed that reduction of the presenting twin and cervical length ≤35 mm were independently associated with post-procedure preterm birth (odds ratio [OR] 8.7, P = 0.001, 95% confidence interval [CI] 2.5-29.8; OR 3.8, P = 0.015, 95% CI 1.3-11).

CONCLUSIONS

Late second trimester selective termination is associated with a higher birthweight centile and lower rates of IUGR and Caesarean delivery, compared with third trimester selective termination. Cervical length 35 mm or less and reduction of the presenting twin are independent risk factors for post-procedural preterm birth. These findings may help determine the optimal time to perform a late selective termination.

First-Trimester Ultrasound Screening in Routine Obstetric Practice

Technologic advances and ultrasonographer-physician experience in fetal imaging have led to significant improvements in our ability to distinguish between normal and abnormal fetal structural development in the latter part of the first trimester. As a critical component of pregnancy care, assessment of fetal anatomy at the end of the first trimester with a standardized imaging protocol should be offered to all pregnant patients regardless of aneuploidy screening results because it has been demonstrated to identify approximately half of fetal structural malformations. Early identification of abnormalities allows focused genetic counseling, timely diagnostic testing, and subspecialist consultation. In addition, a normal ultrasound examination result offers some degree of reassurance to most patients. Use of cell-free DNA alone for aneuploidy screening while foregoing an accompanying early anatomic evaluation of the fetus will result in many anomalies that are typically detected in the first trimester not being identified until later in pregnancy, thus potentially diminishing the quality of obstetric care for pregnant individuals and possibly limiting their reproductive options, including pregnancy termination.

Multifetal pregnancy reductions and selective fetocide in a tertiary referral center - a retrospective cohort study

OBJECTIVES

Multiple pregnancies involve several complications, most often prematurity, but also higher anomaly rates. Reducing fetuses generally improves pregnancy outcomes. We conducted this study to evaluate the obstetrical and neonatal results after multifetal pregnancy reduction (MFPR) in the largest tertiary hospital in Finland.

METHODS

This retrospective cohort study included all MFPR managed in Helsinki University Hospital during a 13 year period (2007-2019). Data on pregnancies, parturients and newborns were collected from patient files. The number of fetuses, chorionicities and amnionicities were defined in first-trimester ultrasound screening.

RESULTS

There were 54 MFPR cases included in the final analyses. Most often the reduction was from twins to singletons (n=34, 63 %). Majority of these (25/34, 73.5 %) were due to co-twin anomaly. Triplets (n=16, 29.6 %) were reduced to twins (n=7, 13 %) or singletons (n=9, 16.7 %), quadruplets (n=2, 3.7 %) and quintuplets (n=2, 3.7 %) to twins. Most (33/54, 61.1 %) MFPR procedures were done by 15+0 weeks of gestation. There were six miscarriages after MFPR and one early co-twin miscarriage. In the remaining 47 pregnancies that continued as twins (n=7, 14.9 %) or singletons (n=40, 85.1 %) the liveborn rate was 90 % for one fetus and 71.4 % for two fetuses.

CONCLUSIONS

Most MFPR cases were pregnancies with an anomalous co-twin. The whole pregnancy loss risk was 11.1 % after MFPR. The majority (70.6 %) of twins were spontaneous, whereas all quadruplets, quintuplets, and 56.3 % of triplets were assisted reproductive technologies (ART) pregnancies. Careful counselling should be an essential part of obstetrical care in multiple pregnancies, which should be referred to fetomaternal units for MFPR option.

Perinatal outcome and timing of selective fetal reduction in dichorionic diamniotic twin pregnancies: a single-center retrospective study

Objective

The study aimed to evaluate the pregnancy outcomes of dichorionic diamniotic twin pregnancies that were reduced to singletons at different gestational ages.

Study design

This was a retrospective cohort study of twin pregnancies that underwent fetal reduction to singletons in a single tertiary referral center between 2011 and 2020. A total of 433 cases were included. The cohort was divided into five groups according to gestational age at surgery: Group A: <16 weeks (125 cases); Group B: 16-19+6 weeks (80 cases); Group C: 20-23+6 weeks (74 cases); Group D: 24-26+6 weeks (48 cases); and Group E: ≥27 weeks (106 cases). Outcome data were obtained by reviewing the electronic medical records or interviews.

Results

Selective reduction was technically successful. The clinical characteristics of the population were not different. The overall live birth rate and the survival rate were 96.5 and 95.4%, respectively. Although the rate of spontaneous miscarriage was comparable, gestational age at delivery significantly differed among groups (p < 0.001). Additionally, there was a trend that gestational age at delivery decreased with the increasing gestational age at surgery in Groups A, B, C, and D, whereas gestational age at delivery in Group E was later than that in Group D. In Groups A, B, C, and D, the rates of preterm birth at <32 weeks and <34 weeks increased with the increasing gestational age at surgery, while the rates in Group E were significantly lower than that in Group D. Regression analysis showed that timing of reduction may be an independent factor after adjusting for maternal age, parity, pre-pregnancy BMI, ART, and cervical length.

Conclusion

Selective reduction performed by experienced hands for a dizygotic abnormal twin is safe and effective. Gestational age at surgery (<26+6 weeks) was inversely correlated with gestational age at delivery and positively with the rate of preterm birth. Reduction after 27 weeks, where legal, can be performed with a good outcome for the retained fetus.

Adverse outcome following selective termination of presenting twin vs non-presenting twin

OBJECTIVE

Data are lacking on the impact on pregnancy outcome of the position of the abnormal fetus in a discordant twin pregnancy undergoing selective termination (ST). Tissue maceration post ST of the presenting twin may lead to early rupture of membranes, amnionitis and preterm labor. The aim of this study was to evaluate pregnancy complications and outcome following ST of the presenting vs non-presenting twin.

METHODS

This was a multicenter retrospective cohort study of dichorionic diamniotic twin pregnancies that underwent ST due to a discordant fetal anomaly (structural or genetic) between 2007 and 2021. The study population was divided into two groups according to the position of the reduced twin (presenting or non-presenting) and outcomes were studied accordingly. The primary outcome was a composite of early complications following ST, including infection, preterm prelabor rupture of membranes and pregnancy loss.

RESULTS

A total of 190 dichorionic twin pregnancies were included, of which 73 underwent ST of the presenting twin and 117 of the non-presenting twin. The groups did not differ in either baseline demographic characteristics or mean gestational age at the time of the procedure. ST of the presenting twin resulted in a significantly higher rate of early complications compared with the non-presenting twin (19.2% vs 7.7%; P = 0.018). Moreover, the rates of preterm delivery (75.3% vs 37.6%; P < 0.001) and neonatal intensive care unit admission (45.3% vs 17.1%; P < 0.001) were higher, and birth weight was lower (P < 0.001), in those pregnancies in which the presenting twin was reduced.

CONCLUSIONS

ST of the presenting twin resulted in a higher rate of adverse pregnancy outcome compared with that of the non-presenting twin. These findings should be acknowledged during patient counseling and, if legislation permits, taken into consideration when planning ST. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Pregnancy and perinatal outcomes of early vs late selective termination in dichorionic twin pregnancy: systematic review and meta-analysis

OBJECTIVE

To evaluate outcomes of dichorionic twin pregnancies undergoing early vs late selective termination of pregnancy (ST).

METHODS

MEDLINE, EMBASE, CINAHL and the Web of Science databases were searched electronically up to March 2022. The primary outcome of this study was pregnancy loss prior to 24 weeks' gestation. The secondary outcomes included preterm birth (PTB) before 37, 34, and 32 weeks, preterm prelabor rupture of membranes (PPROM), gestational age (GA) at delivery, Cesarean delivery, mean birth weight, 5-min Apgar score < 7, overall neonatal morbidity and neonatal survival. Only prospective or retrospective studies reporting data on the outcome of early (before 18 weeks) vs late (at or after 18 weeks) ST in dichorionic twin pregnancies were considered suitable for inclusion. Quality assessment of the included studies was performed using the Newcastle-Ottawa scale for cohort studies. Random-effects head-to-head meta-analysis was used to analyze the data.

RESULTS

Seven studies reporting on 649 dichorionic twin pregnancies were included in this systematic review. The risk of pregnancy loss prior to 24 weeks was significantly lower in dichorionic twin pregnancies undergoing early compared with late ST (1% vs 8%; odds ratio (OR), 0.25 (95% CI, 0.10-0.65); P = 0.004). The risk of PTB was significantly lower in dichorionic twin pregnancies undergoing early compared with late ST when considering PTB before 37 weeks (19% vs 45%; OR, 0.36 (95% CI, 0.23-0.57); P < 0.00001), before 34 weeks (4% vs 19%; OR, 0.24 (95% CI, 0.11-0.54); P = 0.0005) and before 32 weeks (4% vs 20%; OR, 0.21 (95% CI, 0.05-0.85); P = 0.03). The mean birth weight was significantly greater in the early-ST group (mean difference (MD), 392.2 g (95% CI, 59.1-726.7 g); P = 0.02), as was the mean GA at delivery (MD, 2.47 weeks (95% CI, 0.04-4.91 weeks); P = 0.049). There was no significant difference between dichorionic twin pregnancies undergoing early compared with late ST in terms of PPROM (P = 0.27), Cesarean delivery (P = 0.38), 5-min Apgar score < 7 (P = 0.35) and neonatal survival of the non-reduced twin (P = 0.54).

CONCLUSIONS

The risk of pregnancy loss prior to 24 weeks and the rate of PTB before 37, 34 and 32 weeks were significantly higher in dichorionic twin pregnancies undergoing late vs early ST, thus highlighting the importance of early diagnosis of fetal anomalies in twin pregnancies. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Noninvasive prenatal screening (NIPS) for fetal chromosome abnormalities in a general-risk population: An evidence-based clinical guideline of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

This workgroup aimed to develop an evidence-based clinical practice guideline for the use of noninvasive prenatal screening (NIPS) for pregnant individuals at general risk for fetal trisomy 21, trisomy 18, or trisomy 13 and to evaluate the utility of NIPS for other chromosomal disorders.

METHODS

The NIPS Evidence-Based Guideline Work Group (n = 7) relied on the results from the recent American College of Medical Genetics and Genomics (ACMG) systematic review to form the evidentiary basis of this guideline. Workgroup members used the Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision framework to draft recommendations. The guideline underwent extensive internal and external peer review with a public comment period before approval by the ACMG Board of Directors.

RESULTS

Evidence consistently demonstrated improved accuracy of NIPS compared with traditional screening methods for trisomies 21, 18, and 13 in singleton and twin gestations. Identification of rare autosomal trisomies and other microdeletion syndromes with NIPS is an emerging area of interest.

CONCLUSION

ACMG strongly recommends NIPS over traditional screening methods for all pregnant patients with singleton and twin gestations for fetal trisomies 21, 18, and 13 and strongly recommends NIPS be offered to patients to screen for fetal sex chromosome aneuploidy.

Correlation analysis of adverse outcomes for the selective reduction of twin pregnancies

BACKGROUND

Due to the extensive development of assisted reproductive technology, the number of twin pregnancies has increased significantly over recent decades. Twin pregnancy is the most representative type of multiple pregnancies and is associated with high infant morbidity and mortality. Perinatal complications of twin pregnancy are also markedly increased compared with those of single pregnancy. Transabdominal selective reduction (SR) is a remedial intervention. This study aimed to research the adverse outcomes of transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.

OBJECTIVE

The purpose of this study was to examine the adverse outcomes of the transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.

METHODS

A retrospective cohort study of the transabdominal reduction of twin pregnancy was conducted in a single prenatal diagnosis medical centre from September 2012 to October 2020. According to chorionicity, women with twin pregnancies were divided into 2 groups: dichorionic (DC) twin pregnancies and monochorionic (MC) twin pregnancies. Women with DC twin pregnancies underwent potassium chloride reduction, and those with MC twin pregnancies underwent radiofrequency ablation (RFA). The reduction indications included pregnancy complications, foetal abnormalities, and maternal factors. The perinatal outcomes of different chorionic twins after reduction were analysed. Each foetus with an adverse outcome was included. The relative relationship between the reduction weeks and delivery weeks of twins was examined by correlation analysis.

RESULTS

A total of 161 women were included in this study. A total of 112 women had DC twin pregnancies, and 49 women had MC twin pregnancies. Preterm delivery rates were significantly higher in the MC twin reduction group than in the DC twin reduction group prior to 37 weeks (53.1% vs. 29.5%, P = 0.004). The mean gestational age at delivery of the foetuses in the DC twin group that underwent SR was significantly older than that of those in the MC twin group that underwent SR (36.9 ± 4.0 vs. 33.5 ± 6.6 weeks, P = 0.001). The number of DC twins that underwent SR and were delivered after 37 weeks was obviously greater than that of the MC twins that underwent SR (70.5% vs. 46.9%, P = 0.004). The foetal survival rate was 95.5% in the DC twin reduction group and 77.6% in the MC twin reduction group. If the indication of TTTS was not included, there was no significant difference in the foetal survival rate of the DC and MC twin reduction groups (95.5% vs. 86.2%, P = 0.160). Cotwin death 1 week after reduction was greater in the MC group (6.1% vs. 0%, P = 0.027). Compared to other indications, this finding indicated that a significantly lower proportion of women remained undelivered after selective reduction with the indication of TTTS. There was a significant negative correlation between the reduction weeks and delivery weeks of the two groups (P < 0.01), and the best opportunity for reduction was before 22 weeks of gestation.

CONCLUSION

These findings highlighted an obviously negative correlation between the reduction week and delivery week. The transabdominal selective reduction of twin pregnancy should be considered for a lower rate of miscarriage or premature delivery if the reduction week takes place earlier in pregnancy. The rate of preterm delivery was the lowest when transabdominal selective reduction was completed before 22 weeks of gestation. Compared with other RFA indications, a higher rate of premature delivery was shown for MC twins with a reduction indication of TTTS. TTTS with sIUGR might be one of the reasons for the adverse outcomes of reduction for MC twin pregnancy.

The clinical outcomes of selective and spontaneous fetal reduction of twins to a singleton pregnancy in the first trimester: a retrospective study of 10 years

BACKGROUND

Singleton pregnancy is encouraged to reduce pregnancy complications. In addition to single embryo transfer (SET), selective and spontaneous fetal reduction (SEFR and SPFR) can also achieve singleton pregnancies. After SEFR or SPFR, an inanimate fetus remains in the uterus. It is unclear whether the inanimate fetus would adversely affect another fetus or the mother. Previous studies have focused on the differences between pre- and post-reduction. However, studies focusing on the influence of SEFR and SPFR on the remaining fetal development and maintenance of pregnancy are rare.

METHODS

Materials from 5922 patients whose embryo transfer dates ranged from March 2011 to January 2021 were collected. Both the SEFR group (n = 390) and SPFR group (n = 865) had double embryos transferred (DET) and got twin pregnancies, but subsequent selective or spontaneous fetal reduction occurred. The SET group (n = 4667) had only one embryo transferred. All were singleton pregnancies on the 65th day after embryo transfer. Clinical outcomes, including pregnancy outcomes, pregnancy complications, and newborn outcomes, were compared among the three groups.

RESULTS

After adjusting for age, infertility duration, types of infertility, states of embryos, body mass index, and factors affecting SET or DET decisions, multivariate regression analysis revealed that SEFR increased the risk of miscarriage (OR 2.368, 95% CI 1.423-3.939) and preterm birth (OR 1.515, 95% CI 1.114-2.060), and reduced the gestational age (βeta -0.342, 95% CI -0.544- -0.140). SPFR increased the risk of gestational diabetes mellitus (GDM) (OR 1.657, 95% CI 1.215-2.261), preterm premature rupture of membranes (PPROM) (OR 1.649, 95% CI 1.057-2.574), and abnormal amniotic fluid volume (OR 1.687, 95% CI 1.075-2.648). Both SEFR and SPFR were associated with reduced live birth rate (OR 0.522, 95% CI 0.330-0.825; OR 0.671, 95% CI 0.459-0.981), newborn birth weight (βeta -177.412, 95% CI -235.115--119.709; βeta -42.165, 95% CI -83.104--1.226) as well as an increased risk of low-birth-weight newborns (OR 2.222, 95% CI 1.490-3.313; OR 1.510, 95% CI 1.092-2.087).

CONCLUSIONS

DET with subsequent fetal reduction was related to poor clinical outcomes. We recommend that DET with subsequent fetal reduction should only be considered as a rescue method for multiple pregnancy patients with potential complications, and SET is more advisable.

Fetal reduction from twin to singleton gestation: A meta-analysis

OBJECTIVE

To evaluate outcomes of fetal reduction in twin pregnancy.

SEARCH STRATEGY

PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Google Scholar were searched from 1980 through December 2020.

SELECTION CRITERIA

Prospective or retrospective studies of pregnant women with twin gestations who had a transabdominal reduction of twin to singleton pregnancy with a comparison group of ongoing twin gestations.

DATA COLLECTION AND ANALYSIS

Outcomes were meta-analyzed only if reported in at least three studies.

MAIN RESULTS

Six studies with a pooled sample of 2867 women with a twin pregnancy of whom 624 underwent 2-to-1 reduction and 2243 did not. In the fetal reduction group, the odds of preterm birth before 34 and 37 weeks of pregnancy were lower by 36% (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.48-0.86, P < 0.003) and 77% (OR 0.23, 95% CI 0.12-0.44, P < 0.001), respectively, than in the control group, and the odds of hypertensive disorders and cesarean delivery were lower by 75% (OR 0.25, 95% CI 0.15-0.43, P < 0.001) and 65% (OR 0.35, 95% CI 0.20-0.62, P < 0.001), respectively.

CONCLUSION

Twin reduction to singleton pregnancy decreased the possibility of preterm birth, hypertensive disorders in pregnancy and cesarean delivery. Sufficiently powered prospective studies are needed to support these findings.

Perinatal outcome after selective termination in dichorionic twins discordant for congenital anomalies

INTRODUCTION

Our objective was to evaluate the perinatal outcome of selective termination of dichorionic twin pregnancies with discordant anomalies, according to gestational age at time of procedure.

MATERIAL AND METHODS

Retrospective review of 147 dichorionic twin pregnancies referred to our Fetal Medicine Unit between 2003 and 2018 for selective termination. Gestational age at delivery, fetal loss, and overall and 28-day post-delivery survival rates, were evaluated according to gestational age at time of procedure. Selective termination procedure was defined as early, intermediate, and late when performed before 18 weeks, between 18 and 23 weeks, and after 23 weeks, respectively. Kruskal-Wallis and chi-squared test were used to compare groups.

RESULTS

Overall survival at 28 days post-delivery, pregnancy loss, and preterm delivery before 32 weeks of gestation rates were 93.4%, 6.9%, and 15.5%, respectively. When stratified by gestational age at procedure, intermediate selective termination was associated with a lower survival rate than early and late procedures (86% vs. 96.9% and 100%, respectively; p = 0.035), and a nonsignificant trend for higher pregnancy loss (12% vs. 3.1%). Preterm delivery before 32 weeks of gestation occurred in 27% of late procedures, which was significantly higher than in early (9.5%) and intermediate (18.2%) procedures.

CONCLUSIONS

Selective termination in dichorionic twin pregnancies with discordant fetal anomaly is associated with low pregnancy loss and preterm delivery rate, primarily when performed before 18 weeks. When legally possible, late procedures can be a good alternative, particularly in those cases diagnosed beyond the 18th week of gestation.

A fetal reduction from twin to singleton based on sonography and cell-free fetal DNA testing: A sequential approach to old pitfalls

OBJECTIVE

We examined the potential value of combining ultrasound and non-invasive prenatal screening (NIPS) of maternal blood to screen for major aneuploidies as an early approach before selective fetal reduction from twin pregnancy to singleton.

STUDY DESIGN

The sample was composed of pregnant women with di-chorionic di-amniotic twins who chose to undergo fetal reduction to singleton at 12-24 weeks of gestation. These women were asked to provide a blood sample for cell-free fetal DNA (cffDNA) testing prior to fetal reduction.

RESULTS

A total of 24 pregnant women with a twin pregnancy prior to fetal reduction to singleton were enrolled. There were 8 cases with structural anomalies (33.3%) in one twin that dictated fetal reduction. The proportion of patients who underwent selective fetal reduction for fetal abnormalities was larger than in several other studies. The NIPS identified 1 case of Trisomy 13 (4.2%). The other 15 cases (62.5%) had no structural or chromosomal anomalies. The decision to undergo elective reduction of twin pregnancy to singleton was made for social reasons or upon the parents' request. Given the 33% of structural anomalies in the cohort, a cost analysis indicated that this procedure was 6.6-fold less expensive (vs. 4.6-fold with 4% structural anomalies in other publications) than conducting invasive procedures for the entire cohort.

CONCLUSION

The findings suggest that an early anatomical scan and cffDNA can increase the overall safety margin and reduce interventional procedures before elective reduction of twin pregnancy to singleton. However, a larger cohort is needed to confirm these results.

Believing that transferring more embryos will result in increased pregnancy rates: a flawed concept: a SWOT analysis

A belief exists that transferring multiple embryos can improve pregnancy rates. However, this concept is flawed. Multiple factors affect outcomes when transferring embryos, endometrial receptivity, and rates of aneuploidy among them. In this article, we will discuss how factors can affect outcomes at IVF that are independent of the number of embryos transferred. It is important to understand the role of accessory factors on pregnancy rates to be able to counsel patients as per the number of embryos that should be transferred. An understanding of this concept will also lead to a realistic understanding of how multiple embryo transfers may result in better cumulative pregnancy rates than a single transfer of multiple embryos. Finally, we will present a SWOT analysis diagram to help guide clinical decision-making.