Vanishing Twins Conceived Through Fresh In Vitro Fertilization: Obstetric Outcomes and Placental Pathology

Comparison of miscarriage rates in low prognosis patients according to the POSEIDON criteria

OBJECTIVE

The POSEIDON criteria stratified patients with poor ovarian response into four subgroups with exclusive characteristics and assisted reproductive technology success rates. However, limited studies focused on miscarriage in the POSEIDON population. This study aimed to explore whether the miscarriage rate different among low prognosis patients according to POSEIDON criteria.

MATERIALS AND METHODS

This is a retrospective observational study. All clinical pregnancies achieved after in vitro fertilization or intracytoplasmic sperm injection treatment between January 1998 and April 2021 were analyzed. The primary outcome was miscarriage, defined as the pregnancy loss before 20 weeks of gestation age. Miscarriage rate was estimated per clinical pregnancy and gestational sac.

RESULTS

A total of 1222 clinical pregnancies from 1088 POSEIDON patients met the inclusion criteria. The miscarriage rates per clinical pregnancy in each POSEIDON subgroup were as follows: Group 1: 11.7 %, Group 2: 26.5 %, Group 3: 20.9 %, and Group 4: 37.5 %. The miscarriage rate per gestational sac showed a similar trend as the clinical miscarriage rate. Multivariate regression analysis showed that advanced maternal age is an independent factor for miscarriage (Group 2 vs. 1: OR 2.476; Group 4 vs. 3: OR 2.252). Patients with diminished ovarian reserve (DOR) have higher miscarriage risks but without significance (Group 3 vs. 1: OR 1.322; Group 4 vs. 2: OR 1.202).

CONCLUSION

Miscarriage rates differed among low prognosis patients according to the POSEIDON criteria. Age remains a determined risk for miscarriage. DOR might be a potential factor for miscarriage, but it didn't account for a significant impact in POSEIDON patients.

Twin Gestation With Spontaneous Reduction To Singleton

Twin gestations are at increased risk of single intrauterine fetal death. A first-trimester loss is a common complication in twin gestations. The rate of co-twin morbidity and mortality is higher when a single demise occurs in the second and third trimesters. Monochorionicity strongly influences the prognosis for the surviving co-twin. Fetal ultrasound combined with MRI may be able to help predict neurological injury to the surviving co-twin. The rate of co-twin demise decreases with advancing gestation. After single intrauterine fetal demise, monochorionic gestations should be delivered by 34 weeks and dichorionic by 36 to 37 weeks gestation.

Clinical outcomes of vanishing twin syndrome and selective fetal reduction after double embryos transferred in IVF pregnancy: A propensity score matching study

OBJECTIVE

The purpose of this study was to analyze the influence of early vanishing twin syndrome (VTS) and selective fetal reduction (SEFR) on surviving singleton births in in-vitro fertilization (IVF) pregnancy.

METHODS

We collected patients who conceived through IVF and delivered singletons over the past six years. The VT group (n = 194) and SEFR group (n = 144) had underwent double embryos transferred (DET) and only one fetus was born, due to the subsequent one birth reduction. The SET group had one embryo transferred (SET) and gave birth to singleton. Using the propensity score matching (PSM) method to reduce confounding, the VT group and SEFR group were matched and compared with 570 and 576 singleton controls, respectively (SET-I/II group). Obstetric complications and neonatal outcomes were compared. In addition, quantity and quality of transferred embryos of VT (n = 194) and singleton groups (born with singleton after DET and matched with VT group by PSM, n = 554) were compared.

RESULTS

Compared with the SET-I group, VT group had increased incidence of severe obstetric complications, including severe preeclampsia (p = 0.031), oligohydramnios (p = 0.038) and polyhydramnios (p = 0.015). VT group was more likely to show more frequent small for gestational age (SGA) (p = 0.046) and very small for gestational age (VSGA) (p = 0.031). Newborns in the SEFR group had a significantly lower birth weight (p = 0.005) and were more likely to manifest as low birthweight (LBW) (p = 0.009) and very low birthweight (VLBW, birth weight < 1500 g) (p = 0.012), and the incidence of very large for gestational age (VLGA) was lower (p = 0.030), compared with the control group. There were more developmental abnormalities in newborns of VTS, for decreased incidence of SGA (OR 0.156, 95% CI 0.036-0.669), VSGA (OR 0.057, 95% CI 0.006-0.553) and VLGA (OR 0.415, 95% CI 0.212-0.815) in SEFR group. The good quality embryo rate was higher in VT group (72.7% vs. 63.3%, p = 0.001) compared with the singleton group.

CONCLUSIONS

DET with subsequent VTS/SEFR carried a higher rate of adverse clinical outcomes, and the VTS group had worse perinatal outcome compared with SEFR. Therefore, we recommend SET in ART.

Fertility treatment increases the risk of preterm birth independent of multiple gestations

Objective

To investigate the complex interplay between fertility treatment, multiple gestations, and prematurity.

Design

Retrospective cohort study linking the national Center for Disease Control and Prevention infant birth and death data from 2014 to 2018.

Setting

National database from Center of Disease Control and Prevention.

Patients

In total, 19,454,155 live-born infants with gestational ages 22-44 weeks, 114,645 infants born using non IVF fertility treatment (NIFT), and 179,960 via assisted reproductive technology (ART).

Intervention

Noninvasive fertility treatment or ART vs. spontaneously conceived pregnancies.

Main Outcome Measures

The main outcome assessed was prematurity. Formal mediation analysis was conducted to calculate the percentage mediated by multiple gestations.

Results

Newborns born using NIFT or ART compared with those with no fertility treatment had a higher incidence of multiple gestation (no fertility treatment = 3.0%; NIFT = 24.7%; ART = 32.7%; P<.001) and prematurity (no fertility treatment = 11.2%; NIFT = 23.4%; ART = 28.4%; P<.001). Mediation analysis demonstrates that 76.8% (95% confidence interval [CI], 75.2%-78.1%) of the effect of NIFT on prematurity was mediated through multiple gestations. Similarly, 71.2% (95% CI, 70.8%-72.7%) of the effect of ART on prematurity is mediated through multiple gestation. However, the direct effect of NIFT on prematurity is 20.4% (95% CI, 19.0%-22.0%). The direct effect of ART was 24.7% (95% CI, 23.7%-25.6%).

Conclusion

A significant proportion of prematurity associated with fertility treatment is mediated by the treatment itself, independent of multiple gestations.

Risk of Hypertensive Disorders in Pregnancy After Fresh and Frozen Embryo Transfer in Assisted Reproduction: A Population-Based Cohort Study With Within-Sibship Analysis

BACKGROUND

Frozen embryo transfer (frozen-ET) is increasingly common because of improved cryopreservation methods and elective freezing of all embryos. Frozen-ET is associated with higher risk of hypertensive disorders in pregnancy than both natural conception and fresh embryo transfer (fresh-ET), but whether this is attributable to parental factors or treatment is unknown.

METHODS

Using the Medical Birth Registries of Denmark (1994-2014), Norway, and Sweden (1988-2015), linked to data from national quality registries and databases on assisted reproduction, we designed a population-based cohort study with within-sibship comparison. We included 4 426 691 naturally conceived, 78 300 fresh-ET, and 18 037 frozen-ET singleton pregnancies, of which 33 209 sibships were conceived using different conception methods. Adjusted odds ratios (aOR) of hypertensive disorders in pregnancy for fresh-ET and frozen-ET versus natural conception with 95% CI were estimated using multilevel logistic regression, where random effects provided conventional population-level estimates and fixed effects gave within-sibship estimates. Main models included adjustment for birth year, maternal age, parity, and country.

RESULTS

Risk of hypertensive disorders in pregnancy was higher after frozen-ET compared to natural conception, both at population-level (7.4% versus 4.3%, aOR, 1.74 [95% CI, 1.61-1.89]) and within sibships (aOR, 2.02 [95% CI, 1.72-2.39]). For fresh-ET, risk was similar to natural conception, both at population-level (aOR, 1.02 [95% CI, 0.98-1.07]) and within sibships (aOR, 0.99 [95% CI, 0.89-1.09]).

CONCLUSIONS

Frozen-ET was associated with substantially higher risk of hypertensive disorders in pregnancy, even after accounting for shared parental factors within sibships.

Pathology of the Placenta in Singletons after Assisted Reproductive Technology Compared to Singletons after Spontaneous Conception: A Systematic Review

Background: We reviewed the literature comparing the pathological characteristics of singleton births conceived after assisted reproductive technology (ART) with those after spontaneous conception. Methods: We reviewed PubMed, EMBASE, Ovid MEDLINE, Google Scopus, Scholar, Cochrane Central Register of Controlled Trials and the Web of Science for the previous 10 years, up to November 2022. Results: Four eligible studies included 3445 placentas, 806 after ART (IVF/ICSI). Placentas after ART differed in frequency of retroplacental and marginal hematomas (p = 0.04), increased thickness (p = 0.02), higher overall occurrences of vascular and anatomical pathology (p < 0.001) and more frequent marginal (p = 0.001) and membranous (p = 0.02) umbilical cord insertion than placentas from non-ART pregnancies. Conclusion: Further research is needed to determine the extent to which these placental changes in ART pregnancies alter its function and pregnancy outcome.

Factors associated with large-for-gestational-age infants born after frozen embryo transfer cycles

Objective

To examine trends of frozen embryo transfer (FET) proportions and large-for-gestational-age (LGA) incidence and determine risk factors for LGA infants after FET.

Design

Retrospective cohort study.

Setting

Not applicable.

Patients

Frozen embryo transfer cycles.

Interventions

None.

Main Outcome Measures

Singleton LGA infant.

Results

The percentage of FETs increased from 20%-74% of transfers, whereas the rate of LGA among FET singleton births decreased from 18%-12% during 2004-2018. In a subanalysis of 127,525 FET-associated singleton live births during 2016-2018, patient factors associated with LGA were higher-than-normal maternal body mass index (body mass index [BMI], 25.0-29.9 kg/m²; adjusted relative risk [aRR], 1.31; 95% confidence interval [CI], 1.26-1.36; BMI, 30.0-34.9 kg/m²; aRR, 1.48; 95% CI, 1.41-1.55; and BMI, >35 Kg/m²; aRR, 1.68; 95% CI, 1.59-1.77) and ≥1 prior birth vs. none. Low maternal BMI (<18.5 vs. 18.5-24.9 kg/m²) and cycles involving patients who were non-Hispanic (NH) Asian/Native Hawaiian/Pacific Islander, NH Black, or Hispanic (compared with NH White) were at lower risk of LGA infants. Cycle factors associated with LGA included gestational carrier use (aRR, 1.25; 95% CI, 1.16-1.34) and donor sperm (aRR, 1.17; 95% CI, 1.10-1.25).

Conclusions

Although the number and proportion of FET cycles increased from 2004-2018, the rate of LGA after FET decreased. Maternal BMI, parity, and race/ethnicity were the strongest risk factors for LGA infants after FET.

Guideline No. 428: Management of Dichorionic Twin Pregnancies

OBJECTIVE

To review evidence-based recommendations for the management of dichorionic twin pregnancies.

TARGET POPULATION

Pregnant women with a dichorionic twin pregnancy.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline may improve the management of twin pregnancies and reduce neonatal and maternal morbidity and mortality.

EVIDENCE

Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary (e.g., twin, preterm birth). Results were restricted to systematic reviews, randomized controlled trials, controlled clinical trials, and observational studies. There were no date limits, but results were limited to English- or French-language materials.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and weak recommendations).

INTENDED AUDIENCE

Obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, radiologists, and other health care providers who care for women with twin pregnancies.

SUMMARY STATEMENTS

RECOMMENDATIONS.

The vanishing twin: Diagnosis and implications

Vanishing twin syndrome (VTS), defined by first-trimester spontaneous loss of a twin, is a common phenomenon with a reported prevalence of 15-35% of twin pregnancies. The etiology of VTS is obscure. Still, several risk factors have been identified, including an increased number of embryos transferred in pregnancies conceived by in vitro fertilization, an initial increased number of gestational sacs and advanced maternal age. The effect of VTS on obstetric and perinatal outcomes is controversial. Several studies have reported that pregnancies with VTS were associated with increased risk for preterm birth and small for gestational age neonates compared to singleton pregnancies, while others showed no difference in perinatal outcomes. The prevalence of placental vascular and anatomic abnormalities such as small placentas was higher in VTS. These findings lay an essential foundation for understanding how this phenomenon affects obstetric and perinatal outcomes of the surviving pregnancy.

Placental pathology of term singleton live births conceived with fresh embryo transfer compared with those conceived without assisted reproductive technology

OBJECTIVE

To compare placental pathology from term singleton live births conceived with fresh embryo transfer vs. those conceived without assisted reproductive technology (ART).

DESIGN

Retrospective cohort study.

SETTING

Academic fertility center.

PATIENT(S)

Women with a term singleton live birth who conceived after fresh autologous in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles (ART group) and those who conceived without ART.

INTERVENTION(S)

An experienced placental pathologist categorized placental pathology as anatomic, inflammatory, or vascular. Patient characteristics were compared by chi-squared tests, Student's t-test, or nonparametric tests. Multivariate logistic regression models were used to compare placental pathology between pregnancies conceived with and without ART.

MAIN OUTCOME MEASURE(S)

Incidence of anatomic, inflammatory, and vascular placental pathology.

RESULT(S)

There was a higher incidence of placental pathology in the ART group (n = 511) than in the non-ART group (n = 121), specifically anatomic (adjusted odds ratio [aOR] 2.50, 95% confidence interval [CI] 1.42-4.40) and vascular (aOR 2.00, 95% CI 1.13-3.53) pathology. These findings were driven primarily by the significantly higher odds of anatomic (aOR 2.97, 95% CI 1.55-5.66) and vascular (aOR 1.98, 95% CI 1.04-3.75) pathology observed in ICSI pregnancies. Single blastocyst transfers remained associated with increased anatomic pathology (ART: aOR 4.89, 95% CI 2.28-10.49; ICSI: aOR 3.38, 95% CI 1.49-7.71).

CONCLUSION(S)

Fresh embryo transfer is associated with increased anatomic and vascular placental pathology in term singleton live births compared with conception without ART. This finding should be investigated prospectively in a larger cohort of patients.

The Influence of the Vanishing Twin on the Perinatal Outcome of Surviving Singleton in IVF Pregnancy

OBJECTIVE

The purpose of this study was to clarify the influence of the vanishing twin (VT) on the perinatal outcomes in the surviving singleton and further identify the susceptible window.

STUDY DESIGN

Retrospective cohort study.

METHODS

A total of 636 survivors of a vanished co-twin and 11,148 singleton controls were enrolled. The exposed group was further divided into early VT (EVT, VT ≤13 weeks, N = 593) and late VT subgroups (LVT, VT >13 weeks, N = 43) according to the gestational age of the twin vanishing. All participants were conceived through in vitro fertilization (IVF). Perinatal outcomes including gestational age, birthweight, and the incidence of preterm birth (PTB), low birthweight (LBW), small for gestational age (SGA), neonatal intensive care unit (NICU) admission, umbilical cord abnormality, jaundice of the newborn, and oligohydramnios were compared among the groups.

RESULTS

In our birth cohort, about 5.4% of all singleton deliveries originated from vanishing twin pregnancies. Compared with the singletons, both early and late VT pregnancy had a significantly lower birth weight (3337.57±532.24 g and 2916.05±526.07 g vs. 3446.15±526.07 g; p < 0.001 and p < 0.001), more frequent neonatal jaundice (47.0% and 60.5% vs. 40.6%; p = 0.002 and p = 0.008), and decreased incidence of umbilical cord abnormality (15.5% and 7.0% vs. 19.9%; p = 0.009 and p = 0.034). Newborns in the early VT group were more likely to manifest as SGA (5.4% vs. 3.6%, p = 0.002) and suffered oligohydramnios (5.4% vs. 3.4%; p = 0.008) than the primary singletons. In addition, the gestational age of late VT survivors was shorter than that of the controls (37.25 ± 3.25 vs. 39.04 ± 1.63, p = 0.001) and had a significantly higher risk of PTB (30.2% vs. 6.6%; p < 0.001) and NICU admission (27.9% vs. 9.4%, p < 0.001). All differences except for SGA maintain significance after adjusting for maternal age, BMI, and parity.

CONCLUSIONS

Singletons with a vanished co-twin had worse perinatal outcomes compared with the original singletons, with LVT burden even much on the survival one. Therefore, close monitoring during the perinatal period was suggested in this type of neonates. Moreover, elective single embryo transfer should also be fully considered which could tackle the problem at its root.

Non-invasive prenatal testing in the management of twin pregnancies

Twin pregnancies are common and associated with pregnancy complications and adverse outcomes. Prenatal clinical management is intensive and has been hampered by inferior screening and less acceptable invasive testing. For aneuploidy screening, meta‐analyses show that non‐invasive prenatal testing (NIPT) through analysis of cell‐free DNA (cf‐DNA) is superior to serum and ultrasound‐based tests. The positive predictive value for NIPT is driven strongly by the discriminatory power of the assay and only secondarily by the prior risk. Uncertainties in a priori risks for aneuploidies in twin pregnancies are therefore of lesser importance with NIPT. Additional information on zygosity can be obtained using NIPT. Establishing zygosity can be helpful when chorionicity was not reliably established early in pregnancy or where the there is a concern for one versus two affected fetuses. In dizygotic twin pregnancies, individual fetal fractions can be measured to ensure that both values are satisfactory. Vanishing twins can be identified by NIPT. Although clinical utility of routinely detecting vanishing twins has not yet been demonstrated, there are individual cases where cf‐DNA analysis could be helpful in explaining unusual clinical or laboratory observations. We conclude that cf‐DNA analysis and ultrasound have synergistic roles in the management of multiple gestational pregnancies.

What's already known about this topic?

In singleton pregnancies, non‐invasive prenatal testing (NIPT) for fetal aneuploidy is more effective than conventional serum and ultrasound‐based screening tests.

NIPT is more complex in dizygotic twin pregnancies due to the presence of two fetal genotypes.

Overall fetal fraction is higher in twin pregnancies but the individual contribution for each fetus is lower.

What does this study add?

A review of cell‐free DNA testing in twin pregnancies.

Individual fetal fractions in dizygotic twin pregnancies can be measured.

Zygosity can be established using NIPT and this can be particularly useful when there are concerns about chorionicity or determining whether one versus two fetuses are affected.

Vanishing twins can be detected through NIPT and this testing could be considered for some apparently singleton pregnancies with complications.

Risks of nonchromosomal birth defects, small-for-gestational age birthweight, and prematurity with in vitro fertilization: effect of number of embryos transferred and plurality at conception versus at birth

PURPOSE

Excess embryos transferred (ET) (> plurality at birth) and fetal heartbeats (FHB) at 6 weeks' gestation are associated with reductions in birthweight and gestation, but prior studies have been limited by small sample sizes and limited IVF data. This analysis evaluated associations between excess ET, excess FHB, and adverse perinatal outcomes, including the risk of nonchromosomal birth defects.

METHODS

Live births conceived via IVF from Massachusetts, New York, North Carolina, and Texas included 138,435 children born 2004-2013 (Texas), 2004-2016 (Massachusetts and North Carolina), and 2004-2017 (New York) were classified by ET and FHB. Major birth defects were reported by statewide registries within the first year of life. Logistic regression was used to estimate adjusted odds ratios (AORs) and 95% CIs of the risks of a major nonchromosomal birth defect, small-for-gestational age birthweight (SGA), low birthweight (LBW), and preterm birth (≤36 weeks), by excess ET, and excess ET + excess FHB, by plurality at birth (singletons and twins).

RESULTS

In singletons with [2 ET, FHB =1] and [≥3 ET, FHB=1], risks [AOR (95% CI)] were increased, respectively, for major nonchromosomal birth defects [1.13 (1.00-1.27) and 1.18 (1.00-1.38)], SGA [1.10 (1.03-1.17) and 1.15 (1.05-1.26)], LBW [1.09 (1.02-1.13) and 1.17 (1.07-1.27)], and preterm birth [1.06 (1.00-1.12) and 1.14 (1.06-1.23)]. With excess ET + excess FHB, risks of all adverse outcomes except major nonchromosomal birth defects increased further for both singletons and twins.

CONCLUSION

Excess embryos transferred are associated with increased risks for nonchromosomal birth defects, reduced birthweight, and prematurity in IVF-conceived births.