First-trimester fetal reduction to a singleton infant or twins: outcome in relation to the final number and karyotyping before reduction by transabdominal chorionic villus sampling

Is vanishing twin syndrome associated with adverse obstetric outcomes of ART singletons? A systematic review and meta-analysis

PURPOSE

The objective of our meta-analysis was to estimate the effect of VTS on obstetric outcomes of ART singletons.

METHODS

PubMed, Embase, MEDLINE, and ClinicalTrials.gov were searched up to January 2019 to find studies reporting the obstetric outcomes of ART singletons with VTS. Dichotomous data were expressed as odds ratios (OR) with 95% confidence intervals (CI). Continuous data were expressed as weighted mean difference (WMD) with 95% CI.

RESULTS

A total of 17 observational studies encompassing more than 60,000 ART singletons were included in this meta-analysis. The impact of VTS on singletons was highly dependent on the definition of VTS, precisely, the vanishing timing and intrauterine growth stage. When VTS happened at or before 14 weeks, regardless of intrauterine growth stage, there were no differences in terms of gestational age (GA) [WMD = - 0.08, 95% CI = - 0.27, 0.10], preterm birth (< 37 weeks) (PTB) [OR = 1.23, 95% CI = 0.89, 1.70], and low birth weight (< 2.5 kg) (LBW) [OR = 1.56, 95% CI = 1.00, 2.43] in original singletons versus singleton with VTS. On the contrary, VTS occurred after 14 weeks was associated with significantly shorter GW and lower BW, as well as higher risks of PTB and LBW. When the sac reduced in VTS was an empty gestational sac, there would be no differences in GW, PTB, and LBW between singletons versus singletons with VTS, whereas the loss of a fetus with cardiac-activity was associated with adverse obstetric outcomes.

CONCLUSIONS

This meta-analysis suggests whether or not VTS is harmful to obstetric outcomes is highly dependent on the vanishing timing and intrauterine growth stage.

Transabdominal fetal reduction: a report of 124 cases

To prevent fetal loss, preterm delivery, and perinatal morbidity of multifetal pregnancies (MPs), fetal reduction (FR) is offered to some patients. We retrospectively analysed the data of 124 MPs that underwent transabdominal FR to twin (n = 63) and singleton (n = 61) pregnancies at a mean gestational age of 12 + 6 weeks between December 2006 and January 2018. FR was performed transabdominally with the injection of potassium chloride into the intracardiac or intrathoracic space of the fetus or fetuses after ultrasound screening for nuchal translucency and anatomical defects. The initial number of embryos were 48 twins, 63 triplets, 11 quadruplets, and 2 quintuplets. The procedure-related pregnancy loss rate was 0.8% (1/124), the overall pregnancy loss rate was 2.4% (3/124), the fetal loss rate was 1.6% (2/124), and the neonatal death rate was 0.8% (1/124). The baby take-home rates were 96% for twin pregnancies and 96.7% for singletons. This study shows that transabdominal FR is an effective and safe procedure with a pregnancy loss rate of 2.4%.Impact statementWhat is already known on this subject? The incidence of multifetal pregnancies has increased over the years. Because multifetal pregnancies increase perinatal morbidity and mortality due to prematurity, fetal reduction is offed to some patients.What the results of this study add? The results of this study add to the growing body of research on fetal reduction. The study showed that transabdominal fetal reduction is a safe procedure with a pregnancy loss rate of 2.4%.What the implications are of these findings for clinical practice and/or further research? The results of this study can be used in counselling couples with multifetal pregnancies who are considering fetal reduction. Further research is needed to confirm the current findings.

Obstetrical outcomes after first-trimester chorionic villus sampling in twin pregnancies: A retrospective case-control study

AIM

Prenatal diagnostic testing by chorionic villus sampling (CVS) is sometimes recommended for women with twin pregnancies. However, few studies have compared the outcomes between twins with CVS and control twins without intervention. This study aimed to compare the obstetrical outcomes of CVS in twin pregnancies and those in non-intervention twin pregnancies.

METHODS

First-trimester transabdominal CVS was performed on dichorionic-diamniotic twins (n = 54; Group 1) between December 2006 and January 2017 at the Department of Obstetrics and Gynecology at our hospital, and the data were retrospectively analyzed. CVS risks were evaluated by comparing obstetrical outcomes with those of a control population of 155 dichorionic-diamniotic twins without intervention (Group 2).

RESULTS

The difference in the overall fetal loss rate (Group 1, 7.4% vs Group 2, 3.9%; P = 0.287) between the two groups was not statistically significant. The miscarriage rate, defined as delivery at <24 gestational weeks, and early preterm delivery, defined as delivery at <34 gestational weeks, were not significant between the groups (miscarriage: Group 1, 5.6% vs Group 2, 3.2%; P = 0.428; early preterm delivery: Group 1, 11.1% vs Group 2, 9.0%; P = 0.788). The mean gestational age at delivery, birth weights and neonatal intensive care unit admission rate were not statistically significant between the groups. Thus, the overall fetal loss rate and obstetrical outcomes of Group 1 were comparable with those of Group 2.

CONCLUSION

In conclusion, the overall obstetrical outcomes were not significantly different between twins with CVS and control twins with the advantage of enabling early decision-making about selective feticide in twins with CVS.

Ethical considerations in the care of complicated twin pregnancies

Twin gestations are increasing in prevalence worldwide, and are potentially subject to medical complications which present uniquely complex ethical and psychosocial challenges for the pregnant patient and obstetrician to navigate. In this article, we explore these issues as they relate to medical decision-making in cases of discordant growth and discordant anomalies in both monochorionic and dichorionic twin pregnancies, including those affected by twin-twin transfusion syndrome, with particular attention to scenarios in which the individual fetuses hold competing interests. For each of these scenarios, we consider how decisions may positively or negatively impact one or both fetuses, and how familiarity with population outcomes, as well as sensitivity to the complex psychosocial circumstances surrounding these pregnancies, can support and inform shared decision-making.

Twins--twice more trouble?

Twin gestations are fascinating and are also high-risk pregnancies. They account for approximately 3% of all pregnancies in the United States. Major obstetrical complications associated with twin pregnancies include hypertensive disorders of pregnancy, gestational diabetes, and preterm delivery. In addition, the death rate for twins and the rate of severe handicap in very low birth weight survivors of twin pregnancies is greater than that for singleton pregnancies. Ultrasound allows for stepwise evaluations at any time during a twin gestation. Current evidence suggests that uncomplicated diamniotic twins with concordant and appropriate growth beyond 24 weeks' gestation should be managed conservatively and the time and mode of delivery should be determined on the basis of obstetrical history and fetal presentations. Perinatal management of the remaining twin pregnancies depends on good clinical judgment, which is improved by the use of ultrasound imaging.

Are twins growth restricted?

It is now well established that IUGR is associated with an increased risk of a range of adult onset diseases, including cardiovascular disease, obesity, and type 2 diabetes. Infants from twin pregnancies are generally born smaller than singletons; therefore, it has been suggested that twins represent a naturally occurring model of IUGR. Although twin gestations contribute significantly to the population burden of preterm birth and small size at birth, whether twins have the same long-term health consequences as IUGR singletons remains unclear. The purpose of this review is to consider what is currently known about the clinical implications of twinning, the differences that exist between the growth and developmental profiles of singleton and twin fetuses, and to use this as a basis for exploring the question of whether fetuses conceived as twins are analogous to IUGR singletons of similar birthweight and gestation. This question is increasingly important in both the clinical and research settings, because the incidence of twinning is increasing and the long-term implications of reduced size at birth are mostly investigated in species which bear multiple offspring.

Selective reduction in twins and multiple pregnancies

The number of multiple pregnancies has increased, mainly due to the uncontrolled use of the assisted conception techniques. Multifetal pregnancy reduction (MFPR) has been used to reduce the risks associated with these high-risk pregnancies. It is performed in the first trimester of pregnancy by transabdominal injection of potassium chloride into the fetal heart. The risk of miscarriage seems to be associated with the final number of fetuses. A review of the literature suggests that MFPR results in better pregnancy outcome, regardless of the initial number of fetuses. The reduction to a lower number of fetuses reduces fetal losses, prematurity, infant mortality and morbidity.

Intra-uterine exposure to dual fetal programming sequences among surviving co-twins

OBJECTIVE

The dynamics of fetal programming following in utero demise of a co-twin are poorly understood.

METHODS

The authors examined fetal programming using a unique application of the change-point analysis method, and identified two types of fetal programming that occurred when a viable twin sibling died in utero, while the co-twin survived.

RESULTS

In one type, the initial twin fetal programming trajectory was maintained while in a subset of surviving co-twins a "switch" from a twin to a singleton fetal program (dual fetal programming exposure) was observed. The results suggest that the timing in utero of conversion from a twin to a singleton programming pattern occurred slightly earlier among opposite-sex than in same-sex surviving co-twins.

CONCLUSION

For the conversion from a twin to a singleton program to happen, the surviving co-twin must have attained a "critical mass" when the twin sibling died. Whereas, for same-sex surviving co-twins the critical mass for conversion was the 80th percentile of gestational-age specific birth weight, opposite-sex surviving co-twins converted at a lower critical mass (70th percentile). These novel findings warrant further study to confirm the new hithertofore unknown phenomenon of dual fetal programming sequence, and to determine the implications in terms of subsequent morbidity or mortality during infancy, childhood and adult life.

Chorionic villus sampling and the risk of adverse outcome in patients undergoing multifetal pregnancy reduction

OBJECTIVE

The objective of the study was to determine whether patients undergoing chorionic villus sampling (CVS) prior to MPR are at increased risk for adverse outcome compared to those who did not.

STUDY DESIGN

We retrospectively identified multifetal pregnancy reduction (MPR) patients from an established database. Maternal demographic data were collected. Outcomes including complete pregnancy loss prior to 24 weeks' gestation, gestational age at delivery, and birthweight were analyzed.

RESULTS

There was no significant difference in pregnancy loss between the 2 groups (CVS [4%] vs no CVS [7%], P = .098). When stratified by finishing number, there was a significantly lower loss rate in the singleton CVS group (2% vs 9%, P = .025) and no significant difference in reduced twins. There was no significant difference in the average gestational age of delivery or birthweight.

CONCLUSION

CVS prior to MPR does not increase the risk of pregnancy loss. Our data suggest that CVS prior to singleton reduction may decrease the risk of adverse outcome.

Evolving trends in 2000 cases of multifetal pregnancy reduction: a single-center experience

OBJECTIVE

The purpose of this study was to examine changes in multifetal pregnancy reduction (MPR) procedures in 2000 cases and to evaluate evolving trends within the last 1000 MPRs.

STUDY DESIGN

Two thousand patients who underwent MPR were identified. Data were collected from a computerized database. Comparisons were made between the first 1000 patients (group 1) and the second 1000 patients (group 2). In addition, changing trends within group 2 were also analyzed. Differences in proportions were evaluated by chi-square test and Fisher's exact test, as appropriate.

RESULTS

There was a significant difference in the starting and finishing number of fetuses and a significant increase in the use of chorionic villus sampling before MPR in group 2 vs group 1 (43.7% vs 1.5%; P < .0001). The incidence of monochorionicity was significantly higher in group 2 (5.7%), compared with group 1 (2.1%; P < .001).

CONCLUSION

Recent trends in MPR demonstrates significant increases in overall reductions to a singleton fetus, the use of chorionic villus sampling, and the presence of monochorionicity.

ART: iatrogenic multiple pregnancy?

Assisted reproductive technologies (ART) are now widely accepted as effective treatment for most causes of infertility. With improving success rates, attention has turned to the problem of multiple pregnancies, which are associated with a poor perinatal outcome, maternal complications and significant financial consequences. The challenge is to reduce multigestational pregnancies while maintaining good treatment outcomes. Methods to prevent multiple pregnancy include restrictive use of ART in couples with a good chance of spontaneous pregnancy, cautious use of gonadotrophins, and increased use of natural-cycle intra-uterine insemination and elective single embryo transfer in in-vitro fertilization and intracytoplasmic sperm injection. The aim of this article is to review the contribution of fertility treatment to multiple pregnancies and strategies for reducing multiples in ART.

Update on selective reduction

Over the past 25 years fetal reduction has been utilized to reduce the risks of higher-order multiple pregnancies that have resulted from overly successful infertility therapies. The demographics of multiple pregnancy patients have evolved over the past decade, with increasing proportions coming from IVF as opposed to ovulation induction, being older and a higher proportion with donor eggs. Genetic diagnosis prior to reduction is becoming more common and is very safe in experienced hands. For all starting numbers, including twins, reduction to a lower number of fetuses reduces fetal losses, prematurity, and infant mortality and morbidity.