Pregnancy outcome of confined placental mosaicism: meta-analysis of cohort studies

Chromosomal instability in human trophoblast stem cells and placentas

The human placenta, a unique tumor-like organ, is thought to exhibit rare aneuploidy associated with adverse pregnancy outcomes. Discrepancies in reported aneuploidy prevalence in placentas stem from limitations in modeling and detection methods. Here, we use isogenic trophoblast stem cells (TSCs) derived from both naïve and primed human pluripotent stem cells (hPSCs) to reveal the spontaneous occurrence of aneuploidy, suggesting chromosomal instability (CIN) as an inherent feature of the trophoblast lineage. We identify potential pathways contributing to the occurrence and tolerance of CIN, such as autophagy, which may support the survival of aneuploid cells. Despite extensive chromosomal abnormalities, TSCs maintain their proliferative and differentiation capacities. These findings are further validated in placentas, where we observe a high prevalence of heterogeneous aneuploidy across trophoblasts, particularly in invasive extravillous trophoblasts. Our study challenges the traditional view of aneuploidy in the placenta and provides insights into the implications of CIN in placental function.

Limitations of Semi-Automated Immunomagnetic Separation of HLA-G-Positive Trophoblasts from Papanicolaou Smears for Prenatal Genetic Diagnostics

Background: In prenatal genetic diagnostics, the detection of single-gene defects relies on chorionic villus sampling (CVS) and amniocentesis, which carry a miscarriage risk of 0.2-0.3%. To mitigate this risk, fetal trophoblasts have been isolated from a Papanicolaou smear using Trophoblast Retrieval and Isolation from the Cervix (TRIC). However, this method is labor-intensive and has been shown to be challenging to implement in clinical practice. Here, we describe our experiences in using semi-automated immunomagnetic cell sorting for isolating trophoblasts from clinically obtained Papanicolaou smears during ongoing pregnancies. Methods: Using HLA-G-positive Jeg-3 and HLA-G-negative HeLa cell lines in 10%, 1%, and 0.1% dilutions, we tested and optimized the isolation of HLA-G-positive cells using FACS and semi-automated immunomagnetic cell sorting. We used the latter technique for isolation of HLA-G-positive cells from Papanicolaou smears collected from 26 pregnant women, gestational age between 6 and 20 weeks, who underwent CVS. Results: In four independent dilution series, the mean percentages of Jeg-3 cells went from 7.1% to 53.5%, 0.9% to 32.6%, and 0.4% to 2.6% (7.5, 36, and 6.5-fold enrichment, respectively) using immunomagnetic cell sorting. After sorting of the Papanicolaou smears, HLA-G-positive cells were moderately increased in the positive (14.61 vs. 11.63%) and decreased in the negative fraction (7.87 vs. 11.63%) compared to baseline pre-sorting. However, we could not identify fetal cells using XY-chromosomal FISH in a male sample. Conclusions: Our study supports previous findings that careful sampling of fetal cells from Papanicolaou smears in a clinical context poses significant challenges to cell retrieval.

Trophectoderm Biopsy: Present State of the Art

Trophectoderm (TE) biopsy is at present the most widely used procedure for preimplantation genetic testing (PGT). At the blastocyst stage, more TE cells (five to seven) can be obtained for genetic analysis. While removing TE cells and not touching the inner cell mass (ICM), the procedure is less invasive. Due to a natural selection happening between day 3 and day 5, 6 or 7 of human embryo development, fewer embryos will have to be biopsied and tested. An additional benefit, especially in view of aneuploidy testing (PGT-A), is the lower level of mosaicism present at the blastocyst stage. The biopsy procedure involves two steps: laser-assisted zona pellucida (ZP) opening and the excision of five to eight TE cells from the blastocyst with or without additional laser energy. Different protocols have emerged over time with variations regarding the technique, the exact moment of ZP opening, and the method of cell removal. The 'pulling' method involves laser excision, whereas the 'flicking' method represents a mechanical approach with or without laser assistance. Embryo developmental speed reaching the full/expanded or hatching/hatched blastocyst stage dictates the timing of the procedure, mostly on day 5 post-insemination, and to a lesser extent on day 6 or even on day 7. The inclusion of lesser quality or delayed blastocysts may impact the quality of the TE sample as well as the clinical outcome. Intracytoplasmic sperm injection (ICSI) is still the preferred method of fertilization for PGT-M (monogenic disorders) and PGT-SR (structural rearrangements). However, conventional in vitro fertilization (IVF) seems feasible for PGT-A (aneuploidy testing). In the absence of a (conclusive) genetic result, the re-biopsy of cryopreserved blastocysts is possible, however, with reduced clinical outcomes. So far, neonatal outcome post-TE biopsy has so far been reassuringly documented.

Prenatal Ultrasound Findings and Chromosomal Outcomes of Pregnancies with Mosaic Embryo Transfer

BACKGROUND

To investigate prenatal ultrasound findings and the chromosomal outcomes of mosaic embryo transfer.

METHODS

This retrospective study was conducted on pregnant women who underwent mosaic embryo transfer following blastocyst-stage preimplantation genetic testing for aneuploidy (PGT-A) at CHA Gangnam Medical Center from January 2021 to July 2024. Trophectoderm biopsy specimens were collected using standard protocols, and next-generation sequencing profiles were defined as mosaics when displaying copy number counts in the 20-80% range. The results of the PGT-A, the amniocentesis results, the findings of prenatal ultrasounds, and the pregnancy outcomes were analyzed.

RESULTS

A total of 88 mosaic embryos were transferred, of which 77 embryos were successfully implanted. Sixty-seven embryo-maintained pregnancies went beyond 11 weeks (87.0%), all among 58 patients with singleton pregnancies. The chaotic subtype showed the lowest ongoing pregnancy rate, and high-level mosaicism was less frequent in the ongoing group, compared to the total study group and the successful implantation group. Amniocentesis was performed on 33 mothers (56.9%), revealing two cases with abnormal findings that did not correlate with the PGT-A results. Two cases showed abnormalities in the second trimester detailed ultrasound, and both subsequently demonstrated normal findings in the third trimester and after birth. The average gestational age at birth was 38.4 weeks, and the average birth weight was 3313 g. No congenital anomalies were detected in 16 postnatal cases.

CONCLUSIONS

Our study indicated that mosaic embryos can develop into euploid healthy infants with various levels or types of mosaicism, although the postnatal follow-up data are limited. This study is invaluable for counseling clinical results after mosaic embryo transfer, reassuring that, if patients do not have euploid embryos available, mosaic embryos can also be a viable option for transfer.

Revisiting Utility of Fetal Autopsy in Genomic Era

Background: Autopsy has been a gold standard in cases of antenatal detected anomalies or fetal demise. This helped clinicians in getting insights into the future management. In current times, ultrasound and genomic testing has become extremely powerful in further refining the etiological basis; however, fetal autopsy still has its role even now. Material and Methods: We have discussed the utility of fetal autopsy in current times by diving the cases in seven groups. Results: Case based discussions to discuss the utility of fetal autopsy. Conclusions: We suggest that fetal autopsy should be the standard of care in case of any abnormal fetal outcomes alongwith fetal genomic testing. Fetal autopsy is complementary to the ultrasound assessment and genomic investigations in reaching the final diagnosis and provides invaluable information regarding recurrence risk which may not be available when couple plans next pregnancy.

Placental mosaicism for autosomal trisomies: comprehensive follow-up of 528 Danish cases (1983-2021)

BACKGROUND

Mosaicism, characterized by the presence of two or more chromosomally distinct cell lines, is detected in 2% to 4% of chorionic villus samples (CVSs). In these cases, the aberration may be confined to the placenta or additionally present in the fetus. Fetal involvement may manifest as fetal malformations, while confined placental mosaicism (CPM) poses risks such as preterm birth and low birth weight. Differentiating between true fetal mosaicism and CPM at the time of the chorionic villus sampling is challenging and requires follow-up by an amniocentesis and ultrasonography.

OBJECTIVE

To estimate the risk of fetal involvement or adverse pregnancy outcomes for specific chromosomes after detecting mosaicism for an autosomal trisomy in a CVS and identify high (red), intermediate (yellow), and low (green) risk chromosomes. Further, to explore possible associations with level of mosaicism and screening parameters.

STUDY DESIGN

A retrospective descriptive study of all singleton pregnancies with mosaicism detected in CVSs from 1983 to 2021 identified in the Danish Cytogenetic Central Registry and the Danish Fetal Medicine Database.

RESULTS

Of 90,973 CVSs, 528 cases had mosaicism involving an autosomal trisomy and where genetic follow-up had been performed. The overall risk of fetal involvement was 13% (69/528) with extensive variations depending on which chromosome was involved (eg, trisomy 7: 0% [0/55] or trisomy 21: 46% [19/41]). Higher levels of mosaicism in the CVS suggested fetal involvement as mean mosaic level was 55% in true fetal mosaics vs 28% in cases confined to the placenta (P=.0002). In cases with CPM (459/528), the risk of delivering small-for-gestational-age neonates was 14% (48/341). The risk of preterm birth (before 37 weeks) was 15% (51/343). The collective risk of adverse outcome was 22% (76/343) in pregnancies that continued and where information on birth weight and gestational age at birth was available. Adverse outcomes varied substantially between chromosomes. Also, multiple-of-the-median (MoM) values of pregnancy-associated plasma protein A was predictive of these issues as it was significantly lower in cases with adverse outcome compared to cases with a normal outcome (small for gestational age: 0.23 MoM vs 0.47 MoM, P<.0001) or preterm birth: 0.25 MoM vs 0.47 MoM, P<.0001). After the introduction of combined first-trimester screening (cFTS) in 2004, the detection of cases with fetal involvement seemed to increase as the risk before 2004 was 9% (16/174) compared to 15% (53/354) after 2004 (risk ratio: 1.7 [95% CI: 1.0; 2.8]). The risk of adverse outcome in CPM pregnancies increased from 16% (22/139) before 2004 to 27% (55/204) after 2004 (risk ratio 1.7 [95% CI: 1.1; 2.7]).

CONCLUSION

Introducing cFTS increased the detection of placental mosaicism with fetal involvement and CPM with adverse outcome. In cases of mosaicism in CVSs, the risk of fetal involvement and adverse outcomes varied considerably between chromosomes. Importantly, adverse outcomes were seen in CPM for many trisomies besides trisomy 16.

Confined Placental Mosaicism Detected With Non-Invasive Prenatal Testing: Is There an Association Between Mosaic Ratio and Pregnancy Outcome?

OBJECTIVE

Confined placental mosaicism (CPM) is associated with an increased risk for pregnancy complications, such as fetal growth restriction (FGR), preterm birth and hypertensive disorders. Pregnancies with possible CPM can be identified with non-invasive prenatal testing (NIPT). We performed a retrospective cohort study to investigate whether the mosaic ratio, as calculated with the Veriseq v2 used for NIPT, can predict adverse pregnancy outcomes in cases of CPM.

METHOD

A mosaic ratio for trisomies detected by NIPT and obstetric data such as fetal growth, structural fetal anomalies and birthweight were retrospectively studied in a cohort of patients with CPM diagnosed between February 2021 and October 2023. Structural and sex chromosomal aberrations were not included in this study.

RESULTS

Of 122 CPM cases, 52 cases (42.6%) showed adverse perinatal outcomes, including FGR, low birthweight, hypertensive disorders, or preterm birth. A significantly higher mosaic ratio was found in the adverse outcome group compared to those with normal outcome, but a clear-cut threshold could not be set, except potentially for trisomy 16.

CONCLUSION

There is an association between the mosaic ratio and adverse pregnancy outcomes in cases of CPM. However, without a clear-cut threshold, it cannot be used for the individual patient for differentiation between CPM with and without clinical consequences.

Non-Invasive Prenatal Screening from a Genetic Counseling Prospective: Pre and Post-Genetic Counseling Regarding Rare Chromosomal Abnormalities and Incidental Finding

BACKGROUND

Arising in the late 1990s, when a promising role in prenatal diagnostics was first delineated for circulating fetal DNA, non-invasive prenatal tests (NIPTs) have been increasingly used with more frequency and popularity. These exams have been used as a prenatal screening tests for genetic diseases. Initially, they were developed for the investigation of the main fetal chromosomal aneuploidies, but lately they have also been used to rule out genomic microrearrangements and monogenic conditions. However, along with great opportunities and potential, the tests can show inconclusive or unexpected results. Several studies have shown that the current pre-test counseling is often insufficient, and more oriented at providing pieces of information about the identifiable diseases rather than providing extensive information on all possible scenarios which may affect both the fetus and the pregnant mother, especially in the case of an invasive test for the pregnant mother.

METHODS AND RESULTS

We have gathered from the literature on NIPT the main pitfalls, imperfections, and particular cases associated with this innovative diagnostic procedure.

CONCLUSIONS

In view of further improvements in the methods that can limit the inconclusive or unexpected results, this paper aims to reinforce the importance of more accurate pre-test counseling with comprehensive information about the above-mentioned questions, as well as ultrasound use and also the creation of an international consensus statement concerning these topics.

Hypertensive Disorders of Pregnancy: Diagnosis, Management and Timing of Birth

Hypertensive disorders of pregnancy are significant contributors to maternal and perinatal morbidity and mortality. The definition, classification, and management of these disorders have evolved over time. Notably, the disease classification enables caretakers to manage the disease as well as safeguard maternal and fetal health. The approach and management for pregnancies with gestational and chronic hypertension or pre-eclampsia with or without severe features should be adequately elucidated to mitigate adverse perinatal outcomes. This review aimed to present the most recent definition and classification of hypertensive disorders of pregnancy to address their management, determine the optimal timing of birth, and establish short- and long-term follow-up protocols following parturition.

The genetics and clinical outcomes in 151 cases of fetal growth restriction: A Chinese single-center study

OBJECTIVE

To determine the detection rate of chromosomal abnormalities and pregnancy outcomes in fetuses with intrauterine growth restriction. Study design A total of 151 fetal samples with intrauterine growth restriction were divided into the isolated fetal growth restriction (FGR) group, FGR group with structural malformation, and FGR group with non-structural malformation, according to ultrasound abnormalities. The enrolled patients were divided into an early onset FGR group (<32 weeks) and a late-onset FGR group (≥32 weeks). Chromosomal karyotype and microarray analyses were performed and pregnancy outcomes were monitored. Results The karyotypes of 122 patients were analyzed. Four patients exhibited abnormal chromosome numbers or structures. Variations in copy number were detected in 151 cases; 19 cases were found to have chromosomal abnormalities, with a positivity rate of 12.6 %. There was one trisomy in 18 cases, one trisomy in 21 cases, eight pathogenic copy number variations (CNVs), and nine CNVs of unknown clinical significance. The detection rate of FGR combined with structural malformation was significantly higher than that of isolated FGR group. The detection rate of FGR with structural malformations was significantly higher than that with non-structural malformations. The positive detection rate in the FGR group was similar to that in the FGR group with non-structural malformations, with no statistical significance. Chromosomal abnormalities were detected in 17 patients with early onset FGR, with a positivity rate of 13.8 %. Two cases of chromosomal abnormalities were detected in the late-onset FGR group, with a positive rate of 7.1 %, with no statistical significance. A total of 151 fetuses with FGR were followed up for pregnancy outcomes, resulting in 36 cases of pregnancy termination and 13 cases of loss to follow-up. Among the 102 delivered fetuses, six exhibited delayed growth and development, one presented with hypospadias, and another failed the hearing screening. The remaining 94 fetuses demonstrated normal growth and development. Conclusions This study confirms the value of CNV detection in fetuses and dynamic ultrasound monitoring for fetuses with intrauterine growth restriction.

The impact of confined placental mosaicism on prenatal cell-free DNA screening: Insights from a monocentric study of 99 cases

INTRODUCTION

Confined placental mosaicism (CPM) is thought to be one of the main sources of false-positive prenatal cell-free DNA (cfDNA) screening results, but extensive and systematic studies to prove this statement are limited. We evaluate the contribution of CPM to false-positive prenatal cfDNA screening results in the largest cohort published to date.

METHOD

We systematically offered postnatal analysis on placenta and umbilical cord to women who had a negative amniocentesis following a positive prenatal cfDNA screening result. A standardized protocol was used in which (when available) biopsies were taken at five locations in the placenta and umbilical cord.

RESULTS

We analyzed a series of 99 placentas. CPM could be confirmed in 32.3 % of cases (32/99). CPM was detected across all subtypes of chromosomal aberrations (common and rare autosomal trisomies, sex chromosome abnormalities, copy number variations and autosomal monosomies). A lower detection rate was present in umbilical cord biopsies in comparison with placental biopsies. When comparing different sections of the placenta, no clear difference could be observed with regard to the probability of CPM being present nor to the grade of mosaicism.

DISCUSSION

We confirm an important role for CPM in explaining false-positive prenatal cfDNA screening results. Placental regional differences are common. Given its limited clinical relevance, we do however not advocate placental studies in a diagnostic setting.

Etiologically Based Functional Taxonomy of the Preterm Birth Syndrome

Preterm birth (PTB) is a complex syndrome traditionally defined by a single parameter, namely, gestational age at birth (ie, ˂37 weeks). This approach has limitations for clinical usefulness and may explain the lack of progress in identifying cause-specific effective interventions. The authors offer a framework for a functional taxonomy of PTB based on (1) conceptual principles established a priori; (2) known etiologic factors; (3) specific, prospectively identified obstetric and neonatal clinical phenotypes; and (4) postnatal follow-up of growth and development up to 2 years of age. This taxonomy includes maternal, placental, and fetal conditions routinely recorded in data collection systems.

Placental, maternal, fetal, and technical origins of false-positive cell-free DNA screening results

The introduction of noninvasive prenatal testing has resulted in substantial reductions to previously accepted false-positive rates of prenatal screening. Despite this, the possibility of false-positive results remains a challenging consideration in clinical practice, particularly considering the increasing uptake of genome-wide noninvasive prenatal testing, and the subsequent increased proportion of high-risk results attributable to various biological events besides fetal aneuploidy. Confined placental mosaicism, whereby chromosome anomalies exclusively affect the placenta, is perhaps the most widely accepted cause of false-positive noninvasive prenatal testing. There remains, however, a substantial degree of ambiguity in the literature pertaining to the clinical ramifications of confined placental mosaicism and its potential association with placental insufficiency, and consequentially adverse pregnancy outcomes including fetal growth restriction. Other causes of false-positive noninvasive prenatal testing include vanishing twin syndrome, in which the cell-free DNA from a demised aneuploidy-affected twin triggers a high-risk result, technical failures, and maternal origins of abnormal cell-free DNA such as uterine fibroids or unrecognized mosaicisms. Most concerningly, maternal malignancies are also a documented cause of false-positive screening results. In this review, we compile what is currently known about the various causes of false-positive noninvasive prenatal testing.

The role of confined placental mosaicism in fetal growth restriction: A retrospective cohort study

OBJECTIVE

To evaluate which cytogenetic characteristics of confined placental mosaicism (CPM) detected in the first trimester chorionic villi and/or placentas in terms of chromosome aberration, cell lineage involved and trisomy origin will lead to fetal growth restriction and low birthweight.

METHODS

Cohort study using routinely collected perinatal data and cytogenetic data of non-invasive prenatal testing, the first trimester chorionic villi sampling and postnatal placentas.

RESULTS

215 CPM cases were found. Fetal growth restriction (FGR) and low birthweight below the 10th percentile (BW < p10) were seen in 34.0% and 23.1%, respectively. Excluding cases of trisomy 16, 29.1% showed FGR and 17.9% had a BW < p10. The highest rate of FGR and BW < p10 was found in CPM type 3, but differences with type 1 and 2 were not significant. FGR and BW < p10 were significantly more often observed in cases with meiotic trisomies.

CONCLUSION

There is an association between CPM and FGR and BW < p10. This association is not restricted to trisomy 16, neither to CPM type 3, nor to CPM involving a meiotic trisomy. Pregnancies with all CPM types and origins should be considered to be at increased risk of FGR and low BW < p10. A close prenatal fetal monitoring is indicated in all cases of CPM.

Fetal mosaicism, should conventional karyotype always be performed?

BACKGROUND AND PURPOSE

The application of classical cytogenetic and DNA-based molecular techniques to detect cell lineages of mosaicism derived from cultured or noncultured fetal cells may result in discordant results. This retrospective study aimed to assess the inconsistent diagnostic outcomes, technical availability, and limitations of chromosomal microarray analysis (CMA) and karyotyping for mosaicism.

METHODOLOGY

A total of 75 fetuses diagnosed with mosaicism by karyotype analysis or CMA were selected, and the results from both the methods were compared and further analyzed.

RESULTS

A total of 42 (56%, 42/75) CMA results were consistent with karyotypes, consisting of 22 cases of mosaic sex chromosomal abnormalities, 8 routine autosomal aneuploidy cases, 8 other autosome aneuploidy cases, 3 large cryptic genomic rearrangements, and 1 small supernumerary marker chromosome. Discrepancy between karyotype analysis and CMA was observed in 33 (44%, 33/75) mosaicisms involving 15 sex chromosomal abnormalities, 1 routine autosomal aneuploidies, 5 other autosome aneuploidy cases, 8 large cryptic genomic rearrangements, and 4 small supernumerary marker chromosomes.

CONCLUSION

Considering the disparities between methods as well as the cell populations analyzed, both CMA and karyotype analysis have their own advantages and disadvantages. Therefore, CMA should ideally be used in combination with karyotyping to detect more cases of mosaicism than using either test alone.

Chromosome analysis of foetal tissue from 1903 spontaneous abortion patients in 5 regions of China: a retrospective multicentre study

BACKGROUND

Abnormal foetal tissue chromosome karyotypes are one of the important pathogenic factors for spontaneous abortion (SA). To investigate the age and abnormal foetal karyotypes of 1903 couples who experienced SA.

METHODS

A retrospective multicentre study collected age and foetal tissue karyotypes CNV-seq data of 1903 SA couples from 6 hospitals in 5 regions from January 2017 to March 2022. The distribution and correlation of abnormal foetal tissue karyotypes were evaluated by using regions and age.

RESULTS

In our study, 1140 couples (60.5% of the total) had abnormal foetal tissue chromosome karyotypes in all regions. We found that there were differences in the number of abnormal foetal tissue chromosome karyotypes, of which the incidence of trisomy was higher. At the same time, the populations situated in the eastern region had a more triploid (15.5%) distribution, trisomy (58.1%) in the southern region, mosaicism (14.8%) and microduplication (31.7%) in the southwestern region, microdeletion (16.7%) in the northern region. There are variances across areas, and it is more common in the north. The incidence risk of prenatal chromosomal abnormalities varied according to age group.

CONCLUSION

The findings of this study suggest that the karyotypes of patients with abnormal foetal tissue chromosome abortion in different regions were different. Meanwhile, patients ≥ 35 years old had a higher risk of abnormal foetal tissue chromosome abortion.

Chorionic Villous Testing Versus Amniocentesis After Abnormal Noninvasive Prenatal Testing

In the setting of a normal first-trimester ultrasound, an amniocentesis may be a better option than chorionic villous sampling for invasive diagnostic testing after a cell-free DNA high risk for trisomy 13, given the high rates of confined placental mosaicism. In unaffected fetuses, other evaluations should be considered depending on the cell-free DNA results, including maternal karyotyping for monosomy X, uniparental disomy testing for chromosomes with imprinted genes, serial growth scans for trisomy 16, and a workup for maternal malignancy for multiple aneuploidies or autosomal monosomy.

A Novel Paradigm for Non-Invasive Prenatal Genetic Screening: Trophoblast Retrieval and Isolation from the Cervix (TRIC)

As the prevalence of pregnancies with advanced maternal age increases, the risk of fetal chromosomal abnormalities is on the rise. Therefore, prenatal genetic screening and diagnosis have become essential elements in contemporary obstetrical care. Trophoblast retrieval and isolation from the cervix (TRIC) is a non-invasive procedure that can be utilized for prenatal genetic diagnosis. The method involves the isolation of fetal cells (extravillous trophoblasts) by transcervical sampling; along with its non-invasiveness, TRIC exhibits many other advantages such as its usefulness in early pregnancy at 5 weeks of gestation, and no interference by various fetal and maternal factors. Moreover, the trophoblast yields from TRIC can provide valuable information about obstetrical complications related to abnormal placentation even before clinical symptoms arise. The standardization of this clinical tool is still under investigation, and the upcoming advancements in TRIC are expected to meet the increasing need for a safe and accurate option for prenatal diagnosis.

Confined placental mosaicism: placental size and function evaluated on magnetic resonance imaging

OBJECTIVES

Evidence regarding placental function in pregnancies complicated by confined placental mosaicism (CPM) is conflicting. We aimed to compare placental function between CPM and non-CPM pregnancies prenatally and at birth. A secondary objective was to evaluate the relationship between placental function and chromosomal subtype of CPM.

METHODS

This was a retrospective study of pregnancies with CPM and control pregnancies delivered at a tertiary hospital in Denmark between 2014 and 2017. Placental volume and placental transverse relaxation time (T2*) were estimated on magnetic resonance imaging (MRI), fetal weight and uterine artery pulsatility index (UtA-PI) were estimated on ultrasound and fetoplacental ratio was assessed on MRI and at birth. These estimates of placental function were adjusted for gestational age and compared between groups using the Wilcoxon rank-sum test. Within the group of CPM pregnancies, measures of placental function were compared between those at high risk (chromosome numbers 2, 3, 7, 13 and 16) and those at low risk (chromosome numbers 5, 18 and 45X).

RESULTS

A total of 90 pregnancies were included, of which 12 had CPM and 78 were controls. MRI and ultrasound examinations were performed at a median gestational age of 32.6 weeks (interquartile range, 24.7-35.3 weeks). On MRI assessment, CPM placentae were characterized by a lower placental T2* Z-score (P = 0.004), a lower fetoplacental ratio (P = 0.03) and a higher UtA-PI Z-score (P = 0.03), compared with non-CPM placentae. At birth, the fetoplacental ratio was significantly lower (P = 0.02) and placental weight Z-score was higher (P = 0.01) in CPM pregnancies compared with non-CPM pregnancies. High-risk CPM pregnancies showed a reduced placental T2* Z-score (P = 0.003), lower birth-weight Z-score (P = 0.041), earlier gestational age at delivery (P = 0.019) and higher UtA-PI Z-score (P = 0.028) compared with low-risk CPM pregnancies. Low-risk CPM pregnancies did not differ in any of these parameters from non-CPM pregnancies.

CONCLUSIONS

CPM pregnancies are characterized by an enlarged and dysfunctional placenta. Placental function was highly related to the chromosomal type of CPM; placental dysfunction was seen predominantly in high-risk CPM pregnancies in which chromosomes 2, 3, 7, 13 or 16 were involved. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Mitochondrial DNA quantification correlates with the developmental potential of human euploid blastocysts but not with that of mosaic blastocysts

PURPOSE

We aimed to study the association between adjusted mtDNA levels in human trophectoderm biopsy samples and the developmental potential of euploid and mosaic blastocysts.

METHODS

We analyzed relative mtDNA levels in 2,814 blastocysts obtained from 576 couples undergoing preimplantation genetic testing for aneuploidy from June 2018 to June 2021. All patients underwent in vitro fertilization in a single clinic; the study was blinded-mtDNA content was unknown at the time of single embryo transfer. The fate of the euploid or mosaic embryos transferred was compared with mtDNA levels.

RESULTS

Euploid embryos had lower mtDNA than aneuploid and mosaic embryos. Embryos biopsied on Day 5 had higher mtDNA than those biopsied on Day 6. No difference was detected in mtDNA scores between embryos derived from oocytes of different maternal ages. Linear mixed model suggested that blastulation rate was associated with mtDNA score. Moreover, the specific next-generation sequencing platform used have a significant effect on the observed mtDNA content. Euploid embryos with higher mtDNA content presented significantly higher miscarriage rates and lower live birth rates, while no significant difference was observed in the mosaic cohort.

CONCLUSION

Our results will aid in improving methods for analyzing the association between mtDNA level and blastocyst viability.