Faculty Bibliography

OBJECTIVE:To determine the pregnancy outcome potential of mosaic embryos, detected by means of preimplantation genetic screening (PGS) with the use of next-generation sequencing (NGS). DESIGN:Retrospective study. SETTING:Genetics laboratories. PATIENT(S):PGS cycles during which either mosaic or euploid embryos were replaced. INTERVENTION(S):Blastocysts were biopsied and processed with the use of NGS, followed by frozen embryo transfer. Trophectoderm (TE) biopsies were classified as mosaic if they had 20%-80% abnormal cells. MAIN OUTCOME MEASURE(S):Implantation, miscarriage rates, and ongoing implantation rates (OIRs) were compared between euploid and types of mosaic blastocysts. RESULT(S):Complex mosaic embryos had a significantly lower OIR (10%) than aneuploidy mosaic (50%), double aneuploidy mosaic (45%), and segmental mosaic (41%). There was a tendency for mosaics with 40%-80% abnormal cells to have a lower OIR than those with <40% (22% vs. 56%). However, few embryos (n = 34) with a mosaic error in 40%-80% of the TE sample were replaced. There was no difference between monosomic and trisomic mosaics or between entire chromosome mosaicism or segmental mosaicism. Implantation rates were significantly higher (70% vs. 53%), miscarriage rates lower (10% vs. 25%), and OIRs higher (63% vs. 40%) after euploid embryo transfer than after mosaic embryo transfer. CONCLUSION(S):Forty-one percent of mosaic embryos produced an ongoing implantation. Complex mosaic blastocysts had a lower OIR than other mosaics. Mosaic monosomies performed as well as mosaic trisomies and mosaic segmental aneuploidies. The results suggest that embryos with >40% abnormal cells and those with multiple mosaic abnormalities (chaotic mosaics) are likely to have lower OIRs and should be given low transfer priority.

BACKGROUND: Transgender individuals, individuals whose gender identity does not align with their sex assigned at birth, undergoing gender-affirming hormonal or surgical therapies may experience loss of fertility. Assisted reproductive technologies have expanded family-building options for transgender men who were assigned female at birth. CASES: Three transgender men underwent oocyte cryopreservation before gender-affirming hormonal therapy. One patient underwent fertility preservation as an adolescent. Two adult patients had children using their cryopreserved oocytes, with the pregnancies carried by their sexually intimate partners. CONCLUSION: Transgender men with cryopreserved gametes can build families in a way that affirms their gender identity. Obstetrician-gynecologists should be familiar with the fertility needs of transgender patients so appropriate discussions and referrals can be made.

Embryonic mosaicism occurs when two or more cell populations with different genotypes are present within the same embryo. New diagnostic techniques for preimplantation genetic screening (PGS), such as next-generation sequencing, have led to increased reporting of mosaicism. The interpretation of mosaicism is complicated because the transfer of some mosaic embryos has resulted in live births. Mosaic embryos may represent a third category between normal (euploidy) and abnormal (aneuploidy). This category of mosaic embryos may be characterized by decreased implantation and pregnancy potential as well as increased risk of genetic abnormalities and adverse pregnancy outcomes. Euploid embryos should be preferentially transferred over mosaic embryos. Genetic counseling is necessary before the transfer of a mosaic embryo is considered. Certain types of mosaic embryos should be preferentially transferred over others. Transfer of embryos with mosaic trisomies 2, 7, 13, 14, 15, 16, 18, and 21 may pose the most risk of having a child affected with a trisomy syndrome; however, the transfer of embryos with mosaic monosomies or other mosaic trisomies are not devoid of risk. Patients must be counseled about the risk of undetected monosomies or trisomies within a biopsy specimen as well as the risk of intrauterine fetal demise or uniparental disomy with the transfer of mosaic embryos. Until more data are available, patients should be encouraged to undergo another cycle to obtain euploid embryos, when possible, rather than transferring a mosaic embryo.

OBJECTIVE: To determine whether undetected aneuploidy contributes to pregnancy loss after transfer of euploid embryos that have undergone array comparative genomic hybridization (aCGH). DESIGN: Case-control study. SETTING: University-based fertility center. PATIENT(S): Cases included 38 patients who underwent frozen euploid ET as determined by aCGH, resulting in miscarriage. Controls included 38 patients who underwent frozen euploid ET as determined by aCGH, resulting in a live birth. INTERVENTION(S): Next-generation sequencing (NGS) protocols were internally validated. Saved amplified DNA samples from the blastocyst trophectoderm biopsies previously diagnosed as euploid by aCGH were reanalyzed using NGS. Cytogenetic reports of the products of conception for 20 of the pregnancies resulting in miscarriage were available for comparison. MAIN OUTCOME MEASURE(S): The incidence of aneuploidy and mosaicism using NGS within embryos resulting in miscarriage and live birth. RESULT(S): Of euploid embryos analyzed by aCGH resulting in miscarriage, 31.6% were mosaic and 5.2% were polyploid by NGS. The rate of chromosomal abnormalities was significantly higher in embryos resulting in miscarriage (36.8%) than in those resulting in live births (15.8%). The rate of mosaicism was twice as high among embryos resulting in miscarriage than those resulting in live birth, but this was not statistically significant. Next-generation sequencing detected more cases of mosaicism than cytogenetic analysis of products of conception. CONCLUSION(S): Undetected aneuploidy may increase the risk of first trimester pregnancy loss. Next-generation sequencing may detect mosaicism and triploidy more frequently than aCGH, which could help to identify embryos at high risk of miscarriage. Mosaic embryos, however, should not be discarded as some can result in live births.

OBJECTIVE: To assess if SART donor oocyte pregnancy rates are consistent with high percentage of aneuploidy and mosaicism in donor oocyte cycles using Preimplantation Genetic Screening (PGS) with Next Generation Sequencing (NGS). DESIGN: Retrospective study and mathematical analysis. MATERIALS AND METHODS: All trophectoderm biopsy specimens from donor oocyte cycles received by a genetics laboratory were queried for NGS results. The rate of euploidy, aneuploidy, and mosaicism was calculated. A separate analysis was done to find the ongoing pregnancy rate (OPR) from patients' first donor single thawed euploid embryo transfers (STEET) from NGS at a single university fertility center from 2/2015 to 3/2016. Lastly, the 2014 SART National Summary data on non-tested donor embryo transfers and their live birth rates was used to calculate the expected live births from untested donor embryo transfers based on euploidy and mosaicism rates from NGS donor data, applying the the OPR from donor STEET data. The calculated expected live birth rate was then compared to the actual live birth rate of untested donor embryo transfer cycles. RESULTS: 268 donor cycles from 38 IVF centers showed a euploid rate of 48.7%+/-23.8, aneuploid rate of 22.9%+/-20.4 and mosaic rate of 28.4%+/- 21.9 (Table 1). Thirty two patients were included in the donor NGS STEET cycle analysis. The average age at transfer was 42.7 +/-3.9 years with an average donor age of 26.5 +/-2.9 years, for an OPR of 62.2% (n=20/32). The 2014 SART National Summary shows 6070 non-PGS donor egg transfers, averaging 1.7 embryos per transfer, for an estimate of 10319 embryos transferred in total. The reported live birth rate of 53.3% (36.9% singletons, 16.2% twins and 0.2% triplets) gives a cumulative 4242 babies delivered (41.1% per embryo). When the euploid rate of 48.7% is applied, 5025 embryos transferred are estimated to have been euploid. The 62.2% OPR of donor STEETs applied to this gives an expected 3126 singleton deliveries (95% CI 2927-3246). The mosaic rate of 28.4% plus data showing an overall approximate 20%1,2 OPR of mosaic embryos adds 586 (95% CI 421- 524) singleton births. The total expected babies born is 3712 (95% CI 3505-3877) with a live birth rate of 35.9%(95% CI 34.0-37.6) from donor egg transfers. CONCLUSIONS: High rates of aneuploidy and mosaicism in donor oocyte cycles are consistent with the pregnancy rates of untested donor embryo transfers. The use of PGS with NGS can prevent transfer of aneuploid embryos in donor cycles

OBJECTIVE: Single thawed euploid embryo transfer (STEET) decreases the risk of maternal and neonatal morbidity associated with multiple gestation. [1] If transfer of a euploid embryo fails to progress to a clinical pregnancy, we sought to determine if there are identifiable risk factors for a failed second STEET. DESIGN: Retrospective case-control. MATERIALS AND METHODS: All single thawed transfers of embryos designated as euploid by Next Generation Sequencing (NGS) were identified between April 2015 and February 2016 (n=263 transfers, 232 patients). Only patients with a first failed STEET and a subsequent second attempt at elective STEET were included (n=25 patients). Cycle characteristics were compared between those with and without a successful second transfer. Analyses were performed using t-tests and chi square analyses. RESULTS: Clinical pregnancy (fetal heart rate) after NGS diagnosis with STEET is 62.3% in our patient population. After one failed STEET, clinical pregnancy occurred in 56% of patients in the second STEET cycle (p=0.54). Endometrial thickness was significantly increased in patients that achieved clinical pregnancy on the second transfer as compared to those that did not (p=0.01). A lower average age at transfer and higher number of euploid blastocysts remaining was seen in the group achieving pregnancy, but statistical significance was not reached (Table 1). (Table presented) CONCLUSIONS: Lower pregnancy rates might be expected after an initial failed transfer cycle, as the number of good quality blastocysts available is reduced. However, clinical pregnancy rate with a second STEET following an initial failed cycle was similar to the pregnancy rate seen for all first transfers in our population, providing hope for couples. A thicker endometrial echo and younger maternal age at transfer were associated with increased ability to achieve clinical pregnancy in a second STEET after previous failure, indicating a possible underlying uterine or embryologic factor. Further research is needed to identify other potential contributions to pregnancy failure with STEET in order to increase utilization of single embryo transfer

Study question: Does undetected aneuploidy or mosaicism contribute to pregnancy loss after transfer of euploid embryos by array comparative genomic hybridization (aCGH)? Summary answer: NGS detects more cases of mosaicism and triploidy than aCGH, and mosaicism rates are significantly higher among pregnancies resulting in miscarriage than live birth. What is known already: Array CGH is widely used for pre-implantation genetic screening (PGS). NGS is capable of detecting more cases of mosaicism and triploidy (69XXY), which may assist in reducing the incidence of spontaneous abortion and increase ongoing pregnancy rates. Study design, size, duration: Retrospective study of 183 patients undergoing PGS by aCGH between 8/2012 and 5/2015 at New York University Fertility Center and Oregon Reproductive Medicine. Participants/materials, setting, methods: Saved amplified DNA samples from the 183 blastocyst trophectoderm (TE) biopsies previously diagnosed as euploid by aCGH were re-analyzed using the miSeq NGS platform (Illumina, USA) and VeriSeq NGS technology (Illumina, USA). 44 embryos resulting in a biochemical pregnancy, 62 resulting in miscarriage, and 77 resulting in live birth were available for re-analysis. Main results and the role of chance: 25% (11/44) of embryos resulting in biochemical pregnancies were mosaic, and one embryo was found to be triploid (69, XXY) by NGS. 33.9% (21/62) and 3.2% (2/62) of embryos resulting in miscarriage were mosaic and triploid by NGS, respectively. In contrast, the mosaicism rate among embryos resulting in live birth was only 13% (10/77), which was significantly lower than the rate of mosaicism among miscarriages (p = 0.0062, RR 1.78 with 95% CI 1.23-2.5). Limitations, reasons for caution: This study was limited by its retrospective design. Up to 10% of DNA samples that were undergoing re-analysis were excluded due to degraded DNA, although the frequency was similar in all three groups. Wider implications of the findings: Undetected mosaicism may increase the risk of first trimester pregnancy loss. NGS is more sensitive at picking up mosaicism and triploidy than aCGH. Mosaic embryos can be considered for transfer after genetic counseling and informed consent, but they have a higher miscarriage rate as well as unknown post-natal genetic effects

PURPOSE: To determine if day of embryo transfer (ET) affects gestational age (GA) and/or birth weight (BW) at a single university fertility center that primarily performs day 5/6 ET. METHODS: Retrospective cohort study of 2392 singleton live births resulting from IVF/ICSI at a single large university fertility center from 2003 to 2012. Patients were stratified by day 3 or day 5/6 ET. Outcome variables included patient age, gravidity, prior miscarriages, prior assisted reproduction technology cycles, number of embryos transferred, number of single ET, infertility diagnosis, neonatal sex, GA at birth, and BW. Subanalyses were performed on subgroups of preterm infants. A comparison was made between the study data and the Society of Assisted Reproductive Technologies (SART) published data. RESULTS: There was no difference in GA at birth (39 +/- 2.1 weeks for day 3 ET, 39 +/- 1.9 weeks for day 5/6 ET) or BW between ET groups (3308 +/- 568 g for day 3 ET, 3268 +/- 543 g for day 5/6 ET). There was also no difference in the number of preterm deliveries (8.5 % for day 3 ET vs. 10.8 % for day 5/6 ET). The day 5/6 ET study data had significantly fewer pre-term deliveries than the SART day 5/6 ET data. CONCLUSION: In contrast to published SART data, GA and BW were not influenced by day of ET. Data may be more uniform at a single institution. Day 5/6 ET continues to offer improved pregnancy rates without compromising birth outcomes.