Inner cell mass incarceration in 8-shaped blastocysts does not increase monozygotic twinning in preimplantation genetic diagnosis and screening patients

Monochorionic-triamniotic triplet pregnancy following artificial reproductive technology: Report of a rare case in Taiwan

OBJECTIVE

Monochorionic-triamniotic (MCTA) triplet pregnancies following artificial reproductive technologies are uncommon. We report a case in which one of two transferred embryos differentiated into an MCTA triplet. This study aimed to investigate the potential factors contributing to MCTA triplet pregnancy.

CASE REPORT

A 39-year-old woman underwent her second frozen embryo transfer with hatching blastocysts, which resulted in the detection of an MCTA triplet on ultrasonography. She delivered by cesarean section at 32 weeks of gestation, resulting in the birth of three live male infants. Her medical history and in vitro fertilization treatment were reviewed to identify potential causes.

CONCLUSION

The etiology of MCTA triplet pregnancy remains multifactorial. In the presented case, prolonged in vitro culture to the blastocyst stage and inner cell mass splitting were potential contributing factors. Further research is needed to fully understand the complexity of MCTA triplet pregnancy.

Maternal and perinatal risks for monozygotic twins conceived following frozen-thawed embryo transfer: a retrospective cohort study

BACKGROUND

The present study aimed to explore the maternal and perinatal risks in cases of monozygotic twins (MZT) following frozen-thawed embryo transfer (FET).

METHODS

All twin births that were conceived following FET from 2007 to 2021 at Shanghai Ninth People's Hospital in Shanghai, China were retrospectively reviewed. The exposure variable was twin type (monozygotic and dizygotic). The primary outcome was the incidence of neonatal death while secondary outcomes included hypertensive disorders of pregnancy, gestational diabetes, intrahepatic cholestasis of pregnancy, placenta previa, placental abruption, preterm premature rupture of the membranes, Cesarean delivery, gestational age, birth weight, weight discordance, stillbirth, birth defects, pneumonia, respiratory distress syndrome, necrotizing enterocolitis, and neonatal jaundice. Analysis of the outcomes was performed using logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). The causal mediation analysis was conducted. A doubly robust estimation model was used to validate the results. Kaplan-Meier method was used to calculate survival probability. The sensitivity analysis was performed with a propensity score-based patient-matching model.

RESULTS

Of 6101 dizygotic twin (DZT) and 164 MZT births conceived by FET, MZT showed an increased risk of neonatal death based on the multivariate logistic regression models (partially adjusted OR: 4.19; 95% CI, 1.23-10.8; fully adjusted OR: 4.95; 95% CI, 1.41-13.2). Similar results were obtained with the doubly robust estimation. Comparing MZT with DZT, the neonatal survival probability was lower for MZT (P < 0.05). The results were robust in the sensitivity analysis. Females with MZT pregnancies exhibited an elevated risk of preterm premature rupture of the membranes (adjusted OR: 2.42; 95% CI, 1.54-3.70). MZT were also associated with higher odds of preterm birth (prior to 37 weeks) (adjusted OR: 2.31; 95% CI, 1.48-3.67), low birth weight (adjusted OR: 1.92; 95% CI, 1.27-2.93), and small for gestational age (adjusted OR: 2.18; 95% CI, 1.21-3.69) in the fully adjusted analyses. The effect of MZT on neonatal death was partially mediated by preterm birth and low birth weight (P < 0.05).

CONCLUSIONS

This study indicates that MZT conceived by FET are related to an increased risk of neonatal death, emphasizing a potential need for comprehensive antenatal surveillance in these at-risk pregnancies.

Lab partners: oocytes, embryos and company. A personal view on aspects of oocyte maturation and the development of monozygotic twins

The present review addresses the oocyte and the preimplantation embryo, and is intended to highlight the underlying principle of the "nature versus/and nurture" question. Given the diversity in mammalian oocyte maturation, this review will not be comprehensive but instead will focus on the porcine oocyte. Historically, oogenesis was seen as the development of a passive cell nursed and determined by its somatic compartment. Currently, the advanced analysis of the cross-talk between the maternal environment and the oocyte shows a more balanced relationship: Granulosa cells nurse the oocyte, whereas the latter secretes diffusible factors that regulate proliferation and differentiation of the granulosa cells. Signal molecules of the granulosa cells either prevent the precocious initiation of meiotic maturation or enable oocyte maturation following hormonal stimulation. A similar question emerges in research on monozygotic twins or multiples: In Greek and medieval times, twins were not seen as the result of the common course of nature but were classified as faults. This seems still valid today for the rare and until now mainly unknown genesis of facultative monozygotic twins in mammals. Monozygotic twins are unique subjects for studies of the conceptus-maternal dialogue, the intra-pair similarity and dissimilarity, and the elucidation of the interplay between nature and nurture. In the course of in vivo collections of preimplantation sheep embryos and experiments on embryo splitting and other microsurgical interventions we recorded observations on double blastocysts within a single zona pellucida, double inner cell masses in zona-enclosed blastocysts and double germinal discs in elongating embryos. On the basis of these observations we add some pieces to the puzzle of the post-zygotic genesis of monozygotic twins and on maternal influences on the developing conceptus.

Does Post-Warming Extended Culture Duration Affect the Clinical and Obstetric Outcomes of Patients of Advanced Maternal Age? A Single-Center Study

BACKGROUND

The single vitrified-warmed blastocyst transfer (SVBT) cycle has been increasingly utilized for assisted reproductive technology. Women of advanced maternal age (AMA) comprise a significant portion of patients who have undergone 'freeze-all' cycles. This study investigated the association between the post-warming extended culture duration and pregnancy outcomes in patients of AMA.

METHODS

This retrospective cohort study analyzed the outcomes of 697 SVBT cycles between January 2016 and December 2017. The cycles were divided into 3 groups based on the age of the female partners: group I: < 35 years (n = 407), group II: 35-37 years (n = 176); and group III, 38-40 years (n = 114). Data are shown as the mean ± standard error of the mean. Data were analyzed using one-way ANOVA followed by Duncan's multiple range test. Statistical significance was set at P < 0.001.

RESULTS

The blastocyst rate, clinical pregnancy rate, and live birth rate (LBR) was significantly lower in the AMA groups. However, there were no significant differences in LBR in the transfer between the AMA and younger groups according to blastocyst morphology and post-warming extended culture duration.

CONCLUSION

Post-warming extended culture of blastocysts is not harmful to patients of AMA. It could be a useful parameter in clinical counseling and decision making for fertility treatments.

Trophectoderm Biopsy Differentially Influences the Level of Serum β-Human Chorionic Gonadotropin With Different Embryonic Trophectoderm Scores in Early Pregnancy From 7847 Single-Blastocyst Transfer Cycles

OBJECTIVE

To evaluate whether trophectoderm (TE) biopsy differentially influence the level of serum β-human chorionic gonadotropin (β-hCG) with different TE-scored blastocysts transferred in early pregnancy.

METHODS

This retrospective cohort study contained 7847 single-blastocyst transfer cycles executed between January 2019 and June 2020, including 2657 preimplantation genetic testing (PGT) cycles and 5190 in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles. All cycles were classified into biopsy and control groups, and further stratified based on the TE morphological scores into three subgroups: grades A, B, and C for TE scores, respectively. Intra-group and inter-group analyses were performed on serum β-hCG levels on the 12th day after blastocyst transfer (HCG₁₂), and obstetric and neonatal outcomes.

RESULTS

For cycles with a live birth, in grade A TE score subgroups, the HCG₁₂ level did not exhibit statistical significance between the control and biopsy groups after adjustment (769 mIU/mL vs. 753 mIU/mL, P=0.631). In contrast, in grade B and C TE score subgroups, the control group showed a significantly higher level of HCG₁₂ relative to the biopsy group (690 mIU/mL vs. 649 mIU/mL, P=0.001; 586 mIU/mL vs. 509 mIU/mL, P<0.001, respectively). We observed no statistically significant differences in obvious adverse obstetric and neonatal outcomes between the same TE-score subgroups of the biopsy group and control group.

CONCLUSIONS

While blastocysts with higher TE grades produced higher serum β-hCG levels in early pregnancy, TE biopsy might exert a negative impact on serum β-hCG levels by blastocysts with a grade-B TE score and below. TE biopsy did not increase the risk for adverse obstetric and neonatal outcomes.

An investigation of the effects of laser-assisted zona pellucida drilling on the preimplantation mouse embryo and the competency of embryo implantation

OBJECTIVE

To investigate the impact of laser-assisted zona pellucida (ZP) drilling on the mouse embryo, with particular emphasis on molecular mechanisms, and the efficiency of embryo attachment capability using an in vitro model of implantation.

DESIGN

Experimental study.

SETTING

Academic research laboratory.

ANIMAL(S)

C57BL/6JOlaHsd mouse embryos and B6C3F1 × B6D2F1 mouse embryos.

INTERVENTION(S)

Eight-cell stage mouse embryos were randomly assigned to a laser-assisted ZP drilling group (n = 343), ZP partial drilling group (n = 312), ZP quarter thinning group (n = 289), and control group (n = 353). Embryos were cultured in vitro from E2.5 to E4.5 for 48 hours. To investigate the capacity to implant, E4.5 embryos (laser-assisted drilling group [n = 46], ZP partial drilling group [n = 28], ZP quarter thinning group [n = 26], and control group [n = 36]) were then transferred onto an attachment model on the basis of Ishikawa cells and cultured for another 72 hours.

MAIN OUTCOME MEASURE(S)

Blastocyst formation, hatching status, and hatching morphology at E4.5. Blastocyst cell components, the extent of apoptosis in embryonic cells (DNA fragmentation, caspase-3 activation, and expression of apoptosis-related genes), the expression of heat shock protein 70, and differentially expressed genes (DEGs) generated by RNA sequencing. Fully hatched embryo rate and stable attachment rate in the in vitro attachment model.

RESULT(S)

There were no significant differences between the laser-assisted ZP manipulation groups and control group with respect to the formation of blastocysts, cell number, embryonic cell apoptosis, and cellular stress. All 3 of the laser-assisted ZP manipulations significantly increased the hatching rate at E4.5 compared with the control group, especially the ZP drilling group. However, only the ZP drilling group was associated with a significantly higher proportion of "8"-shaped hatching blastocysts. Furthermore, RNA sequencing identified 48 DEGs between blastocysts from the laser-assisted drilling group and control group; the metabolic pathways were significantly enriched in these DEGs. In addition, there were no significant differences between the laser-assisted ZP manipulation groups and control group with respect to the rate of stable attachment at E7.5, although a significantly higher entrapment rate was observed in the ZP drilling group.

CONCLUSION(S)

Laser-assisted ZP manipulations did not induce cellular apoptosis or stress in mouse blastocysts. Nevertheless, for the first time, we found that laser-assisted ZP drilling could alter the embryonic transcriptome and may affect metabolic activity. Furthermore, although laser-assisted ZP manipulations can enhance the initiation of hatching, it is evident that ZP drilling comes with a potential risk of embryo entrapment.

On the origin of zygosity and chorionicity in twinning: evidence from human in vitro fertilization

Assisted reproduction is presumed to increase monozygotic twin rates, with the possible contribution of laboratory and medical interventions. Monozygotic dichorionic gestations are supposed to originate from the splitting of an embryo during the first four days of development, before blastocyst formation. Single embryo transfers could result in dichorionic pregnancies, currently explained by embryo splitting as described in the worldwide used medical textbooks, or concomitant conception. However, such splitting has never been observed in human in vitro fertilization, and downregulated frozen cycles could also produce multiple gestations. Several models of the possible origins of dichorionicity have been suggested. However, some possible underlying mechanisms observed from assisted reproduction seem to have been overlooked. In this review, we aimed to document the current knowledge, criticize the accepted dogma, and propose new insights into the origin of zygosity and chorionicity.

The mystery of monozygotic twinning II: What can monozygotic twinning tell us about Amyoplasia from a review of the various mechanisms and types of monozygotic twinning?

Monozygotic (MZ) twins ("identical twins") are essentially unique to human beings. Why and how they arise is not known. This article reviews the possible different types of MZ twinning recognized in the previous article on twins and arthrogryposis. There appear to be at least three subgroups of MZ twinning: spontaneous, familial, and those related to artificial reproductive technologies. Each is likely to have different etiologies and different secondary findings. Spontaneous MZ twinning may relate to "overripe ova." Amyoplasia, a specific nongenetic form of arthrogryposis, appears to occur in spontaneous MZ twinning and may be related to twin-twin transfusion.

Monozygotic twinning following embryo biopsy at the blastocyst stage

Objective:

Monozygotic twinning incidence following preimplantation genetic testing in embryos at cleavage-stage does not appear to increase; however, data regarding the possible impact of the blastocyst-stage preimplantation genetic testing is lacking. We compared the incidence of monozygotic twinning in preimplantation genetic testing cycles performed at the blastocyst-stage, versus cycles without PGT, following single embryo transfer.

Methods:

In this retrospective cohort study, we analyzed the incidence of twin pregnancies in patients undergoing intracytoplasmic sperm injection and blastocyst-preimplantation genetic testing (253 cycles), versus a period-matched control population of patients undergoing intracytoplasmic sperm injection and single embryo transfer without preimplantation genetic testing (606 cycles).

Results:

The overall monozygotic twinning rate was 14/859 (1.6%) per clinical pregnancy. The incidence of zygotic splitting following intracytoplasmic sperm injection and preimplantation genetic testing was 3.5% (95% Confidence interval 1.8%-6.6%) versus 0.8% (95% Confidence interval 0.3%-1.9%) following intracytoplasmic sperm injection without preimplantation sperm injection. After adjusting for potential confounders, preimplantation genetic testing cycles were associated with an increase in the incidence of monozygotic twinning when compared to cycles without embryo biopsy (Odd ratio 3.44, 95% Confidence interval 1.05-11.27, p=0.041).

Conclusions:

Our findings indicate that embryo biopsy for preimplantation genetic testing performed at the blastocyst stage is associated to an increase in the incidence of monozygotic twinning. Further validation in larger sample size studies is warranted. Patients undergoing preimplantation genetic testing must receive proper counselling about the potential risks of the technique.

Trophectoderm biopsy for preimplantation genetic test and technical tips: A review

BACKGROUND

Recently, the Japan Society of Obstetrics and Gynecology initiated a clinical study of preimplantation genetic test for aneuploidy. There will be a great need for a standardized embryo biopsy technique in Japan. However, the gold standard trophectoderm (TE) biopsy procedure has not been established, and this review outlines the clinical use of TE biopsy.

METHODS

Based on literature, the method and associated techniques for TE biopsy, a dissection method of TE cells from blastocysts, were investigated.

MAIN FINDINGS

Two TE biopsy methods are used, namely assisted hatching (herniating) and non-assisted hatching (direct suction); however, it is not clear which of these methods is superior. It is critical to understand whether the flicking or pulling method is beneficial.

CONCLUSION

Non-assisted hatching biopsy method may cause blastocyst collapse with a higher probability, and it may extend the biopsy time. The biopsy procedure should be performed within 3 minutes, and thus direct TE suction may have greater disadvantages. It is a fact that pulling method of TE dissection with laser pulse is simple; however, excess laser shots may induce a higher frequency of mosaicism. It is important to understand that each technique of TE biopsy has benefits and disadvantages.

Preimplantation Genetic Testing for Breast Cancer

Breast cancer (BC), a malignant tumor characterized mainly by a lump in the breast and a change in breast shape, has plagued many women of childbearing age in Nigeria today. This has thus propelled many to find both prophylactic and curative agents to combat BC in affected persons. This article extensively reviews a method of preventing BC in the offspring of affected parents, known as preimplantation genetic testing (PGT) – an assisted reproductive technique that selects genetically unaffected embryo(s) to be transferred to the uterus of a mother upon in vitro fertilization and standard genetic analysis. The present study also seeks to present the techniques involved in PGT that have been reported to prevent the inheritance of BC, its benefits and risks, related case studies in Africa and other continents, and ethical issues surrounding the application of assisted reproduction for BC testing. To achieve these, a thorough search was conducted in reputable scientific journals of reproduction and cancer, and expert knowledge was consulted with regard to these aspects of health and reproduction. Upon reviewing this very important subject, it was confirmed that the beneficial role of assisted reproduction in the field of science and the homes of many cannot be overestimated. This review of the role of PGT in BC prevention will enlighten the understanding of many – creating awareness that with PGT, BC-affected women can have not only children, but also healthy and genetically unaffected children.

Evaluation of preimplantation genetic testing based on next-generation sequencing for balanced reciprocal translocation carriers

RESEARCH QUESTION

Can next-generation sequencing (NGS) based on copy number variation sequencing (CNV-Seq) identify normal/balanced embryos in balanced reciprocal translocation carriers and what are their reproductive outcomes?

DESIGN

One hundred couples with balanced reciprocal translocation who underwent a total of 134 preimplantation genetic testing (PGT) cycles between January 2015 and October 2017 were evaluated. Trophectoderm cells of blastocysts were biopsied for CNV-Seq-based NGS. All the balanced/normal blastocysts were vitrified and cryopreserved. Single balanced/normal blastocysts were warmed and transferred in the subsequent frozen embryo transfer (FET) cycle.

RESULTS

During the study period, 400 blastocysts were analysed by NGS-PGT, of which 109 (27.25%) were balanced and euploid. A total of 52 blastocysts were transferred in the FET cycle. Clinical pregnancy was confirmed in 34 women (65.38%), with a miscarriage rate of 2.94%; 26 healthy term babies were born, including 24 singletons and one set of twins, while eight couples had ongoing pregnancies. Amniocentesis revealed a fetal chromosome status that was consistent with the NGS-PGT results. Female carriers had a significantly higher blastocyst rate than did the male carriers (37.01% versus 31.27%, P = 0.04). The transferable blastocyst rate was higher in couples treated with gonadotrophin-releasing hormone (GnRH) antagonist than in those treated with GnRH agonist (38.20% versus 24.37%, P = 0.01). However, neither carrier sex nor ovarian stimulation protocol influenced the clinical pregnancy rate.

CONCLUSIONS

CNV-Seq-based NGS is an efficient and reliable PGT method for balanced reciprocal translocation.