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Medical providers have an ethical duty to disclose clinically significant errors involving gametes and embryos. Although not mandatory, disclosure of errors causing no harm or near misses is recommended. In addition, clinics should have written policies in place for reducing and disclosing errors. [ABSTRACT FROM AUTHOR]

To study and compare the preimplantation genetic testing for monogenic disorders (PGT-M) results, and to evaluate the treatment cycle outcomes of embryos derived from a single pronucleus (1PN) vs. two pronuclei (2PN). A retrospective cohort study from January 2018 to December 2022 involving in vitro fertilization (IVF)-PGT-M treatment cycles. Single, academically affiliated fertility center. A total of 244 patients underwent 351 IVF-PGT-M treatment cycles. Embryo biopsy with molecular testing for a monogenic disorder. The molecular diagnosis results and clinical outcomes after the transfer of embryos derived from 1PN and 2PN in IVF-PGT-M treatment cycles. Embryos derived from 1PN have a significantly low developmental potential with a lower rate of embryos that underwent biopsy compared with 2PN-derived embryos; 1PN-derived embryos demonstrated a significantly lower number of blastocysts (24% vs. 37.9%) and top-quality blastocysts (22.3% vs. 48.1%) compared with 2PN-derived embryos. Lower successfully completed and unaffected PGT-M results were achieved in 1PN compared with 2PN-derived embryos (47.1% vs. 65.5% and 18.7% vs. 31.6%, respectively), with significantly higher abnormal molecular results (39.6% vs. 22.7%). The embryo transfer of 24 1PN-derived embryos with no affected genetic disorder resulted in 5 (20.8%) clinical pregnancies and 4 (16.7%) live births (LBs). Within the limits of fewer embryos derived from 1PN that yielded unaffected embryos suitable for transfer, the clinical pregnancy and LB rate of 1PN embryos undergoing PGT-M are reassuring. We, therefore, suggest applying PGT-M to embryos derived from 1PN embryos to improve the cumulative clinical pregnancy and LB rates. [ABSTRACT FROM AUTHOR]

To assess whether the change in embryo morphology from precryopreservation to postthaw is associated with the embryo transfer success rates in single euploid embryo transfer cycles. Retrospective cohort study. Academic affiliated fertility clinic. Patients who underwent a single euploid embryo transfer cycle from September 2016 to April 2022 were included. A decision support tool was used to assign each embryo a reproductive potential score on the basis of the day of biopsy, expansion, and grade of trophectoderm and inner cell mass at the time of cryopreservation and after thaw. Embryos were divided into 4 groups: group 1 included embryos with the same score after thaw (reference); group 2 included those with a higher score; group 3 included those with a lower score; and group 4 included those that did not re-expand after thaw. No interventions administered. The primary outcome was the live birth rates (LBRs) per embryo transfer. The secondary outcomes included the chemical pregnancy, clinical pregnancy, and clinical pregnancy loss rates. Comparative statistics and univariate analyses were performed using the Kruskal-Wallis and χ2tests. Multivariate logistic regression fitted with generalized estimating equation was performed to compare the odds of live birth between groups. A total of 7,750 embryo transfers performed for 4,613 patients met inclusion criteria: 5,331 in group 1; 486 in group 2; 1,726 in group 3; and 207 in group 4. In the univariate analysis, there was a statistically significant difference in the LBR between groups 1, 2, 3, and 4 (55.8% vs. 51.4%, 47.5%, and 26.6%). Logistic regression controlling for oocyte age, antimüllerian hormone, body mass index, endometrial thickness, year of embryo transfer, time from thaw to final grading, and embryo score before cryopreservation showed significantly lower odds of live birth when the embryo was downgraded (odds ratio [OR], 0.70; confidence interval [CI], 0.62–0.79) or did not re-expand (OR, 0.36; CI, 0.26–0.51) than those with no change in score. When controlling for all variables, there was a significant increase in the odds of live birth between embryos that had a higher score after thaw and those without a change (OR, 1.42; CI, 1.14–1.76). There was no significant difference in the clinical pregnancy loss rate among the 4 groups. The change in the quality of the embryo after thaw is an important factor in embryo transfer success. In an adjusted analysis, the chemical and clinical pregnancy rates and LBR per embryo transfer all significantly decrease in embryos that were downgraded or did not expand on the day of single euploid embryo transfer. Embryos that re-expand and have improved quality after thaw have the highest odds of live birth. [ABSTRACT FROM AUTHOR]

To study the development and clinical validation of the ART Pipetting Robot for the IVF Laboratory (APRIL), a liquid-handling robot customized for the precise preparation of microdroplet culture dishes in the field of in vitro fertilization (IVF). A prospective randomized study conducted at an academic IVF center comparing mouse and human embryo outcomes and quantitative measures of accuracy in embryo dishes prepared using APRIL compared with standard manual preparation. Academic IVF center. The study involved the assessment of the automated culture dish preparation system, APRIL, compared with manual preparation methods in the context of IVF treatment. ART Pipetting Robot for the IVF Laboratory is an enclosed liquid-handling robot equipped with custom three-dimensional–printed adapters and designed to dispense embryo culture media and mineral oil into microdroplet culture dishes. The study evaluated the precision and consistency of APRIL in culture dish preparation by looking at droplet mass, pH of prepared media droplets, and mouse and human embryo development rates. Clinical implementation was assessed by comparing embryo development and outcomes in dishes prepared by APRIL and human embryologists. Compared with embryo culture dishes prepared using standard manual procedures, embryo culture dishes prepared using APRIL demonstrated a greater than 10-fold improvement in consistency (coefficient of variation, 0.46% vs. 6%–7%), maintained optimal pH levels (pH range, 7.281–7.33 vs. 7.275–7.311), and had a greater mouse embryo blastocyst rate (100% vs. 90%–91%). Human embryos cultured in dishes prepared by APRIL had a higher rate of development on days 3 (92.4% vs. 82.6%) and 5 (19.75% vs. 15.57%), and a total number of usable embryos (50.3% vs. 46.1%) compared with manually prepared dishes, although the last two outcomes did not reach statistical significance. The results suggest that the use of an automated robotic system for preparation of embryo culture dishes may improve accuracy and outcome measures while reducing the need for trained laboratory personnel to prepare the dishes manually. [ABSTRACT FROM AUTHOR]

In this review, we take a fresh look at embryo assessment and selection methods from the perspective of diagnosis and prognosis. On the basis of a systematic search in the literature, we examined the evidence on the prognostic value of different embryo assessment methods, including morphological assessment, blastocyst culture, time-lapse imaging, artificial intelligence, and preimplantation genetic testing for aneuploidy. [ABSTRACT FROM AUTHOR]

To examine the relationship between the day of embryo cryopreservation and large for gestational age (LGA) infants in women undergoing frozen embryo transfers (FETs) after cryopreservation on days 2–7 after fertilization and to compare the risk of the day of embryo cryopreservation to other possible risk factors of LGA after FET cycles. Retrospective cohort study. Society of Assisted Reproduction Clinical Outcomes Reporting System. Women undergoing FET cycles. Day of cryopreservation. Singleton LGA infant. A total of 33,030 (18.2%) FET cycles in the study group (n = 181,592) resulted in LGA infants during the study period of 2014–2019. There was an increase in LGA risk when cryopreservation was performed from day 2 (13.7%) to days 3–7 (14.4%, 15.0%, 18.2%, 18.5%, and 18.9%). In the log-binomial model, the risk increased compared with days 2–3 combined when cryopreservation was performed on days 5–7 (adjusted relative risk [aRR] 1.32, 95% confidence interval [CI] 1.22–1.44 for day 5, aRR 1.34, 95% CI 1.23–1.46 for day 6, and aRR 1.42, 95% CI 1.25–1.61 for day 7). Other factors most associated with LGA risk in the log-binomial model were preterm parity of >3 compared with 0 (aRR 1.82, 95% CI 1.24–2.69) and body mass index (BMI) of >35 kg/m2 compared with normal weight (aRR 1.94, 95% CI 1.88–2.01). Increasing gravity, parity, BMI, number of oocytes, and embryo grade were also associated with LGA in this model. Asian, Black, Hispanic, and combined Hawaiian and Pacific Islander were protective factors in the model compared with White patients. Low BMI (<18.5 kg/m2) was also considered a protective factor in the model compared with normal BMI. Duration of embryo culture was associated with an increased risk of LGA in this study cohort when controlling for known confounders such as maternal BMI and parity. This study sheds new light on the possible link between FET and LGA infants. [ABSTRACT FROM AUTHOR]

The oocyte, a long-lived, postmitotic cell, is the locus of reproductive aging in women. Female germ cells replicate only during fetal life and age throughout reproductive life. Mechanisms of oocyte aging include the accumulation of oxidative damage, mitochondrial dysfunction, and disruption of proteins, including cohesion. Nobel Laureate Bob Edwards also discovered a "production line" during oogonial replication in the mouse, wherein the last oocytes to ovulate in the adult-derived from the last oogonia to exit mitotic replication in the fetus. On the basis of this, we proposed a two-hit "telomere theory of reproductive aging" to integrate the myriad features of oocyte aging. The first hit was that oocytes remaining in older women traversed more cell cycles during fetal oogenesis. The second hit was that oocytes accumulated more environmental and endogenous oxidative damage throughout the life of the woman. Telomeres (Ts) could mediate both of these aspects of oocyte aging. Telomeres provide a "mitotic clock," with T attrition an inevitable consequence of cell division because of the end replication problem. Telomere's guanine-rich sequence renders them especially sensitive to oxidative damage, even in postmitotic cells. Telomerase, the reverse transcriptase that restores Ts, is better at maintaining than elongating T. Moreover, telomerase remains inactive during much of oogenesis and early development. Oocytes are left with short Ts, on the brink of viability. In support of this theory, mice with induced T attrition and women with naturally occurring telomeropathy suffer diminished ovarian reserve, abnormal embryo development, and infertility. In contrast, sperm are produced throughout the life of the male by a telomerase-active progenitor, spermatogonia, resulting in the longest Ts in the body. In mice, cleavage-stage embryos elongate Ts via "alternative lengthening of telomeres," a recombination-based mechanism rarely encountered outside of telomerase-deficient cancers. Many questions about Ts and reproduction are raised by these findings: does the "normal" T attrition observed in human oocytes contribute to their extraordinarily high rate of meiotic nondisjunction? Does recombination-based T elongation render embryos susceptible to mitotic nondisjunction (and mosaicism)? Can some features of Ts serve as markers of oocyte quality? [ABSTRACT FROM AUTHOR]

To determine how often a noneuploid result from a single trophectoderm (TE) biopsy tested with the next-generation sequencing (NGS)–based preimplantation genetic testing for aneuploidy (PGT-A) is concordant with rebiopsies tested with a single-nucleotide polymorphism (SNP) array-based PGT-A platform. Blinded prospective cohort study. University-affiliated fertility center. One hundred blastocysts were chosen from donated samples; on TE biopsy with NGS-based PGT-A, 40 had at least one whole chromosome full copy number aneuploidy alone, 20 had a single whole chromosome intermediate copy number ("whole chromosome mosaic"), 20 had a single full segmental aneuploidy (segA), and 20 had a single segmental intermediate copy number ("segmental mosaic"). Four rebiopsies were collected from each embryo: 3 TE biopsies and the remaining embryo. Each rebiopsy was randomized, blinded, and assessed with an SNP array-based PGT-A platform that combines copy number and allele ratio analyses, without mosaicism reporting. Concordance between the NGS result and rebiopsy results and within each embryo's blinded rebiopsy results. Next-generation sequencing–diagnosed whole chromosome aneuploidy (WCA) was reconfirmed in 95% (95% confidence interval [CI], 83%–99%) of embryos; 2 embryos with NGS-diagnosed WCA were called euploid on all conclusive rebiopsies. Among embryos with NGS-diagnosed whole chromosome mosaicism, 35% (95% CI, 15%–59%) were called euploid and 15% (95% CI, 3%–38%) were called whole chromosome aneuploid on all conclusive rebiopsies. A total of 30% (95% CI, 12%–54%) of embryos with NGS-diagnosed segA and 65% (95% CI, 41%–85%) of embryos with NGS-diagnosed segmental mosaicism were called euploid on all conclusive rebiopsies. In total, 13% (95% CI, 6%–25%) of embryos with NGS-diagnosed full copy number aneuploidy and 50% (95% CI, 34%–66%) of embryos with NGS-diagnosed mosaicism had uniformly euploid SNP results. Conversely, all embryos with at least one noneuploid SNP result (n = 72) either had SNP-diagnosed aneuploidy on another rebiopsy from the same embryo or NGS-diagnosed aneuploidy/mosaicism involving the same chromosome. Next-generation sequencing–diagnosed WCA is highly concordant with rebiopsies tested with an SNP array-based PGT-A; however, whole chromosome mosaicism, segA, and segmental mosaicism are less concordant, reinforcing that embryos with these results may have reproductive potential and be suitable for transfer. [ABSTRACT FROM AUTHOR]

To understand the clinical risks associated with the transfer of embryos classified as a mosaic using preimplantation genetic testing for aneuploidy. Analysis of data collected between 2017 and 2023. Multicenter. Patients of infertility treatment. Comparison of pregnancies resulting from embryos classified as euploid or mosaic using the 20%–80% interval in chromosomal intermediate copy numbers to define a mosaic result. Rates of spontaneous abortion, birth weight, length of gestation, incidence of birth defects, and chromosomal status during gestation. Implanted euploid embryos had a significantly lower risk of spontaneous abortion compared with mosaic embryos (8.9% [n = 8,672; 95% confidence interval {CI95} 8.3, 9.5] vs. 22.2% [n = 914; CI95 19.6, 25.0]). Embryos with mosaicism affecting whole chromosomes (not segmental) had the highest risk of spontaneous abortion (27.6% [n = 395; CI95 23.2, 32.3]). Infants born from euploid, mosaic, and whole chromosome mosaic embryos had average birth weights and lengths of gestation that were not statistically different (3,118 g and 267 days [n = 488; CI95 3,067, 3,169, and 266, 268], 3052 g and 265 days [n = 488; CI95 2,993, 3,112, and 264,267], 3,159 g and 268 days [n = 194; CI95 3,070, 3,249, and 266,270], respectively). Out of 488 infants from mosaic embryo transfers (ETs), one had overt gross abnormalities as defined by the Centers for Disease Control and Prevention. Most prenatal tests performed on pregnancies from mosaic ETs had normal results, and only three pregnancies produced prenatal test results reflecting the mosaicism detected at the embryonic stage (3 out of 250, 1.2%; CI95 0.25, 3.5). Although embryos classified as mosaic experience higher rates of miscarriage than euploid embryos (with a particularly high frequency shortly after implantation), infants born of mosaic ETs are similar to infants of euploid ETs. Prenatal testing indicates that mosaicism resolves during most pregnancies, although this process is not perfectly efficient. In a small percentage of cases, the mosaicism persists through gestation. These findings can serve as risk-benefit considerations for mosaic ETs in the fertility clinic. [ABSTRACT FROM AUTHOR]

To study the likelihood of obtaining at least 1 euploid embryo for transfer in poor ovarian response (POR) diagnosed per Bologna and Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number (POSEIDON) criteria, and compare it between groups and with patients without POR. Retrospective cohort study. Women undergoing an ovarian stimulation cycle with intention to pursue preimplantation genetic testing for aneuploidy. Bologna criteria and the POSEIDON classification system were applied to characterize each stimulation cycle as POR or not. Cycles identified as POR by POSEIDON were subdivided into groups I, II, III, and IV as defined by this classification system. The proportion of cycles resulting in at least 1 euploid blastocyst. Other outcome measures included cycle yields (metaphase II oocytes, fertilized oocytes, blastocysts, and euploid blastocysts), and euploidy rate per embryo cohort. A total of 6,889 cycles were included, of which 3,653 (53.0%) were classified as POR per POSEIDON criteria: 1.5% (100/6,889) in group I, 3.2% (222/6,889) in II, 11.9% (817/6,889) in III, and 36.5% (2,514/6,889) in IV. Per Bologna criteria, 23.4% (1,612/6,889) of cycles were classified as POR. Group I had similar likelihood of obtaining at least 1 euploid embryo (97.0%; 95% confidence interval, 91.5%–99.2%) as cycles not deemed POR (91.9%; 95% confidence interval, 90.9%–2.8%), whereas this decreased significantly with each subsequent POSEIDON group (II: 77.9%, 72.0%–82.9%; III: 70.5%, 67.3%–73.5%; IV: 44.8%, 42.9%–46.7%) and those meeting Bologna criteria had the lowest rates (31.9%, 29.7%–34.3%). Cycle yields correlated with ovarian reserve testing results, whereas euploidy rates were associated with age. Although younger POSEIDON groups (I and III) have higher euploidy rates than older groups (II and IV), each incremental POSEIDON group poses a higher risk of having no euploid blastocysts; with POSEIDON I being no different from non-POSEIDON, and Bologna having the worst prognosis. Although ovarian reserve appears to have little impact on euploidy rates, it remains a key prognostic factor for having at least 1 euploid embryo available for transfer through its impact on oocyte yield. To our knowledge, this is the first study to provide the odds ratio of this outcome depending on the degree of POR. [ABSTRACT FROM AUTHOR]

Cryopreservation has revolutionized the treatment of infertility and fertility preservation. This review summarizes the milestones that paved the way to the current routinary clinical implementation of this game-changing practice in assisted reproductive technology. Still, evidence to support "the best practice" in cryopreservation is controversial and several protocol adaptations exist that were described and compared here, such as cumulus-intact vs. cumulus-free oocyte cryopreservation, artificial collapse, assisted hatching, closed vs. open carriers, and others. A last matter of concern is whether cryostorage duration may impact oocyte/embryo competence, but the current body of evidence in this regard is reassuring. From social and clinical perspectives, oocyte and embryo cryopreservation has evolved from an afterthought when assisted reproduction was intended for immediate pregnancy with supernumerary embryos of secondary interest to its current purpose, which primarily is to preserve fertility long-term and more comprehensively allow for family planning. However, the initial consenting process, which still is geared to short-term fertility care, may no longer be relevant when the individuals that initially preserved the tissues have completed their reproductive journey. A more encompassing counseling model is required to address changing patient values over time. [ABSTRACT FROM AUTHOR]

Preimplantation development is the only stage of human development that can be studied outside the body in real time, as human embryos can be produced by in vitro fertilization and cultured in the laboratory as self-contained structures until the blastocyst stage. Here, we focus some of the key cellular and morphogenetic processes by which the 1-cell embryo is transformed gradually into a blastocyst ready for implantation. Although most of our knowledge about the dynamic series of events patterning preimplantation human development derives from work in mouse embryos, we discuss key differences that could exist with humans. Furthermore, we highlight how new approaches may enable to reveal many of the unknown processes driving human preimplantation development, particularly using noninvasive imaging and genetic technologies. [ABSTRACT FROM AUTHOR]

Over the past 4 decades our ability to maintain a viable human embryo in vitro has improved dramatically, leading to higher implantation rates. This has led to a notable shift to single blastocyst transfer and the ensuing elimination of high order multiple gestations. Future improvements to embryo culture systems will not only come from new improved innovative media formulations (such as the inclusion of antioxidants), but plausibly by moving away from static culture to more dynamic perfusion-based systems now made a reality owing to the breakthroughs in three-dimensional printing technology and micro fabrication. Such an approach has already made it feasible to create high resolution devices for intracytoplasmic sperm injection, culture, and cryopreservation, paving the way not only for improvements in outcomes but also automation of assisted reproductive technology. Although improvements in culture systems can lead to further increases in pregnancy outcomes, the ability to quantitate biomarkers of embryo health and viability will reduce time to pregnancy and decrease pregnancy loss. Currently artificial intelligence is being used to assess embryo development through image analysis, but we predict its power will be realized through the creation of selection algorithms based on the integration of information related to metabolic functions, cell-free DNA, and morphokinetics, thereby using vast amounts of different data types obtained for each embryo to predict outcomes. All of this will not only make assisted reproductive technology more effective, but it will also make it more cost effective, thereby increasing patient access to infertility treatment worldwide. [ABSTRACT FROM AUTHOR]

This review discusses the use of artificial intelligence (AI) algorithms in noninvasive prediction of embryo ploidy status for preimplantation genetic testing in in vitro fertilization procedures. The current gold standard, preimplantation genetic testing for aneuploidy, has limitations, such as an invasive biopsy, financial burden, delays in results reporting, and difficulty in results reporting, Noninvasive ploidy screening methods, including blastocoel fluid sampling, spent media testing, and AI algorithms using embryonic images and clinical parameters, are explored. Various AI models have been developed using different machine learning algorithms, such as random forest classifier and logistic regression, have shown variable performance in predicting euploidy. Static embryo imaging combined with AI algorithms have demonstrated good accuracy in ploidy prediction, with models such as Embryo Ranking Intelligent Classification Algorithm and STORK-A outperforming human grading. Time-lapse embryo imaging analyzed by AI algorithms has also shown promise in predicting ploidy status; however, the inclusion of clinical parameters is crucial to improving the predictive value of these models. Mosaicism, an important aspect of embryo classification, is often overlooked in AI algorithms and should be considered in future studies. The integration of AI algorithms into microscopy equipment and Embryoscope platforms will facilitate noninvasive genetic testing. Further development of algorithms that optimize clinical considerations and incorporate minimal-necessary covariates will also enhance the predictive value of AI in embryo selection. Artificial intelligence-based ploidy prediction has the potential to improve pregnancy rates and reduce costs in in vitro fertilization cycles. [ABSTRACT FROM AUTHOR]

Time-lapse imaging (TLI) allows continuous monitoring of embryo development without disturbing culture conditions by removing embryos from the incubator. The study of embryo kinetics using TLI has given rise to some new markers for embryo selection that are able to document and evaluate embryo morphology and the timing of developmental events through continuous live image tracking. Time-lapse imaging has emerged as a powerful tool for creating predictive models of in vitro fertilization outcomes. Fourty-seven articles were included in the present review to investigate the current situation of TLI in in vitro fertilization laboratories. Morphokinetics of the embryo during its in vitro development have been described using parameters indicative of the different events capable of predicting the ability to reach blastocyst stage, implantation and pregnancy rates, live birth outcome, and embryo ploidy. [ABSTRACT FROM AUTHOR]

Noninvasive and minimally invasive preimplantation genetic testing for aneuploidy (PGT-A) is a tool that may one day become the gold standard for embryonic chromosomal screening. Investigations on this topic have ranged from studying the culture media of embryos to the fluid inside the blastocoel, all in an attempt to find a reliable source of DNA without the need to biopsy the embryo. There is great interest across the board, both from those for and against biopsy, in a reliable test process that would give the patient and provider the same information possible from a biopsy without the risk. We aim to explore the current available research to better understand the utility and accuracy of PGT-A with these new sampling techniques. General concordance rates in comparison with biopsy-based PGT-A are promising, but it is clear that additional research and understanding are needed before adopting noninvasive and minimally invasive PGT-A as a widely used tool with strong clinical utility. [ABSTRACT FROM AUTHOR]

: To investigate the impact of recryopreservation on embryo viability and the outcomes of in vitro fertilization (IVF) by comparison with single cryopreservation. There is a lack of consensus and reliable evidence regarding the impact of recryopreservation techniques on human embryos, particularly with respect to embryo viability and IVF outcomes. Systematic review and meta-analysis. Not applicable. Various databases such as PubMed, Embase, Cochrane Library, and Scopus were searched until October 10, 2022. All comparative studies comparing embryonic and IVF outcomes between repeated and single cryopreservation of embryos were included. The random-effect and fixed-effect meta-analysis models were used to pool the odds ratio (OR) and corresponding 95% confidence intervals (CIs). A subgroup analysis was performed based on different methods of cryopreservation and different times of embryo cryopreservation or transfer. Outcomes referring to embryo surviva l, IVF outcomes (including clinical pregnancy rate, embryo implantation rate, miscarriage rate, and live birth rate), and neonatal outcomes (including low birth weight rate and preterm birth rate) were evaluated. Fourteen studies were eligible for the present meta-analysis, involving 4,525 embryo transfer cycles in total (3,270 cycles with single cryopreservation [control group] and 1,255 with recryopreservation [experimental group]). Decreased embryo survival (OR, 0.51; 95% CI, 0.27–0.96) and clinical pregnancy rates (OR, 0.47; 95% CI, 0.23–0.96) were found in embryos that were recryopreserved by slow freezing. The live birth rate of revitrified embryos was also notably affected (OR, 0.60; 95% CI, 0.38–0.94). Overall, recryopreservation resulted in a decreased live birth rate (OR, 0.67; 95% CI, 0.50–0.90) and an increased miscarriage rate (OR, 1.52; 95% CI, 1.16–1.98) compared with single cryopreservation. No significant difference was found in neonatal outcomes. When embryos were cryopreserved and transferred at the blastocyst stage, both the embryo implantation rate (OR, 0.59; 95% CI, 0.39–0.89) and live birth rate (OR, 0.60; 95% CI, 0.37–0.96) were significantly different between the 2 groups. The present meta-analysis suggested that recryopreservation, compared with single cryopreservation, can lead to impaired embryo viability and a lower rate of IVF success, with no affected neonatal outcomes. Clinicians and embryologists should retain a cautious attitude toward recryopreservation strategies. CRD42022359456 [ABSTRACT FROM AUTHOR]

Building families through the adoption of children has been supported by human society throughout history. The ethical appropriateness of patients donating embryos to other patients for family building, or for research, is well established and is affirmed by this Committee. The use of the term "adoption" for embryos is inaccurate and should be avoided. This document replaces the ASRM Ethics Committee statement by the same name, last published in 2016. [ABSTRACT FROM AUTHOR]