Current Issue Highlights

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    The International Glossary on Infertility and Fertility Care, 2025†

    May 08, 2026: 41(6):892-909

    STUDY QUESTION

    What updates of the International Glossary on Infertility and Fertility Care are required, to reflect contemporary scientific knowledge, social needs, and inclusive definitions, while harmonizing international communication across clinical, research, policy, and public domains?

    SUMMARY ANSWER

    This 4th edition presents 348 consensus-based terms and definitions, including numerous revisions from the previous edition and 79 newly introduced definitions reflecting advances in reproductive science, technology, and evolving social contexts.

    WHAT IS KNOWN ALREADY

    Previous glossary editions (2006, 2009, 2017) established internationally recognized definitions related to clinical practice, research, and policy. The 2017 edition comprised 283 terms and, among many others, expanded the concept of infertility to include not only its recognition as a disease, but also as an impairment of function generating disability. The glossary has been extensively used worldwide and has contributed to international standardization of data collection, appropriate comparison of outcome measures, and provided a reference for all stakeholders including policy makers.

    STUDY DESIGN, SIZE, DURATION

    Under guidance of the organizing committee, 21 professionals from across the world, and representing expertise in different sub-specialties, formed five working groups: clinical definitions; outcome measures; embryology laboratory; clinical and laboratory andrology; and epidemiology, public health and gender related definitions. The definitions from the previous glossary were evaluated and new terms identified. All definitions were then reviewed by an international advisory panel of nine experts that evaluated the glossary from scientific, ethical, cultural, and policy perspectives.

    PARTICIPANTS/MATERIALS, SETTING, METHODS

    Between November 2024 and October 2025, periodical virtual meetings were held within and between working groups and the organizing committee. Following circulation of the first consensually agreed draft, a one-day in-person meeting with representatives of all working groups and members of the international advisory panel was held at ESHRE, June 2025. Most terms and definitions were discussed and agreed. In the absence of agreement, further discussions were held between the organizing committee, working group chairs and members of the advisory panel. It had been determined at the outset that final disagreement would be resolved via a two-third majority vote. All terms and definitions were, however, reached by consensus and adopted following a final round of review and approval by all authors.

    MAIN RESULTS AND THE ROLE OF CHANCE

    The glossary now includes 348 terms. Compared to the previous edition, 14 terms were deleted, numerous terms modified and 79 new terms were added. Modifications reflect current scientific knowledge, technological advancements, and inclusivity related to gender and family structures. Chance does not play a role, as all definitions are consensus-based.

    LIMITATIONS, REASONS FOR CAUTION

    Some terms may require future refinement as scientific knowledge evolves and societal contexts change. The glossary reflects consensus rather than empirical testing of all definitions.

    WIDER IMPLICATIONS OF THE FINDINGS

    This glossary provides a global reference for standardized terminology, supporting clinical care, research, international comparisons, policy making, patient communication, and reproductive health literacy.

    STUDY FUNDING/COMPETING INTEREST(S)

    Neither ICMART, responsible for conducting this project, nor any of the participants received specific financial support for their activities in this project. Ferring provided ICMART with a fixed amount to cover venue costs and a one-day hotel accommodation for participants attending the in-person meeting held prior to the ESHRE Congress in June 2025. Disclosures were provided by all authors, and none reported any conflict of interest related to this manuscript.

    TRIAL REGISTRATION NUMBER

    N/A.

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    The impact of endometrial preparation on pregnancy loss in vitrified-warmed euploid blastocyst transfer cycles: a randomized controlled trial

    May 04, 2026: 41(6):910-917

    STUDY QUESTION

    Does artificial cycle (AC) endometrial preparation result in increased pregnancy loss rates in patients undergoing vitrified-warmed euploid blastocyst transfer (frozen embryo transfer (FET))?

    SUMMARY ANSWER

    The randomized controlled trial (RCT) demonstrates that artificial endometrial preparation is associated with significantly higher early pregnancy loss (EPL) compared to natural cycles when transferring euploid embryos.

    WHAT IS KNOWN ALREADY

    The increased use of FET cycles has fueled discussion regarding the optimal endometrial preparation method. While earlier reviews found no significant differences in pregnancy outcomes between preparation strategies, recent studies suggest that artificial preparation may be associated with higher pregnancy loss rates and, more recently, with hypertensive disorders of pregnancy. However, these findings were not confirmed in a recent RCT using genetically untested embryos. Since up to 70% of EPLs are attributed to genetic anomalies in the embryo, analyzing FET of euploid embryos provides a more accurate evaluation of the impact of endometrial preparation on pregnancy loss.

    STUDY DESIGN, SIZE, DURATION

    An RCT was conducted in a university hospital (May 2019–May 2024) investigating the impact of endometrial preparation on pregnancy loss in FET. A power calculation based on internal data determined that 261 patients per arm were needed to detect an increase in pregnancy loss from 9.9% in tNC-FET to 18.4% in AC-FET (80% power, 5% significance). Due to safety concerns regarding hypertensive disorders following AC-FET, the trial was discontinued after enrolling 354 patients.

    PARTICIPANTS/MATERIALS, SETTING, METHODS

    Women aged 18–42 years undergoing FET after preimplantation genetic testing for aneuploidy (PGT-A) with or without testing for a monogenic disorder (PGT-M) or a structural chromosomal rearrangement (PGT-SR) were randomized (1:1) to either true NC-FET (spontaneous ovulation without luteal phase support (LPS)) or AC-FET (using estradiol and single-route LPS). Only the first FET per patient using a euploid blastocyst was included. The primary outcome was EPL (before 8 weeks of gestation). Secondary outcomes included clinical pregnancy rate (CPR), ongoing pregnancy, live birth rate (LBR), and obstetric outcomes.

    MAIN RESULTS AND THE ROLE OF CHANCE

    Between May 2019 and May 2024, 354 patients were randomized (NC-FET: 178, AC-FET: 176). In the intention-to-treat analysis, EPL per started FET cycle occurred in 6.7% of patients in the NC-FET group and 14.2% in the AC-FET group (P = 0.022). Additionally, EPL per positive hCG was 9.0% in the NC-FET group and 21.6% in the AC-FET group (P = 0.006). CPRs were significantly higher in the NC-FET group (72.5% versus 52.3%, P < 0.001), as were LBRs (67.4% versus 47.2%, P < 0.001). The study was prematurely terminated after obstetrical safety concerns of AC-FET emerged from other studies. While obstetric and neonatal outcomes did not differ significantly between groups in our study, the trial was not powered for these endpoints. Despite the premature halt, the observed difference in EPL was in line with the anticipated effect size.

    LIMITATIONS, REASONS FOR CAUTION

    Although this randomized study achieved the estimated difference in the primary outcome, the premature cessation necessitates cautious interpretation. Additionally, the absence of luteal phase progesterone measurements in both groups represents a limitation. Nevertheless, these findings offer valuable insights for counseling patients on the optimal FET preparation method.

    WIDER IMPLICATIONS OF THE FINDINGS

    The results of this RCT reinforce concerns regarding AC-FET cycles. In addition to previously reported higher obstetrical complications, an increased risk of pregnancy loss was associated with AC-FET cycles. This protocol should therefore preferentially be used in patients with (premature) ovarian insufficiency or those resistant to ovulation induction agents.

    STUDY FUNDING/COMPETING INTEREST(S)

    No external funding was received for this study. C.R. declares speaker’s fees from Organon, Ferring, Abbott, IBSA; travel support from Gedeon Richter, Ferring, Organon, Abbott, IBSA. S.S.-R. declares employment and stock ownership in IVIRMA Lisboa; grants/contracts (paid to institution) from Theramex, Organon, Gedeon-Richter, Roche Pharmaceuticals; consulting fees from Organon, IBSA, Besins; travel support (paid to institution) and speaker’s fees from Organon, Ferring, Theramex, IBSA, Gedeon-Richter, Abbott, and Besins; being a member of the Executive Committee, Past-Senior Deputy of Safety and Quality SIG for ESHRE. S.M. declares grants/contracts (to institution) from Merck, Gedeon Richter, Ferring; advisory board for Oxolife; speakers’ fees and travel support from Merck, Gedeon Richter, Ferring, and IBSA. W.V. declares research grants (to institution) from Merck B.V. and IBSA; consulting fees (to institution) from CooperSurgical and Cook Medical; advisory board (payment to institution) for Goodlife; speaker fees (to institution) from CooperSurgical, Merck B.V., Organon Pharma B.V., Ferring B.V., and Gedeon Richter. C.B. declares speaker’s fees from Abbott, Ferring Pharmaceuticals, IBSA, Organon, Gedeon Richter, and Merck. The other authors declare no conflict of interest related to this manuscript.

    TRIAL REGISTRATION NUMBER

    Clinicaltrials.gov: NCT03976544

    TRIAL REGISTRATION DATE

    6 April 2019

    DATE OF FIRST PATIENT’S ENROLMENT

    25 May 2019

Latest Articles

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    The International Glossary on Infertility and Fertility Care, 2025

    Human Reproduction. May 08, 2026: 41(6):892-909

    STUDY QUESTION

    What updates of the International Glossary on Infertility and Fertility Care are required, to reflect contemporary scientific knowledge, social needs, and inclusive definitions, while harmonizing international communication across clinical, research, policy, and public domains?

    SUMMARY ANSWER

    This 4th edition presents 348 consensus-based terms and definitions, including numerous revisions from the previous edition and 79 newly introduced definitions reflecting advances in reproductive science, technology, and evolving social contexts.

    WHAT IS KNOWN ALREADY

    Previous glossary editions (2006, 2009, 2017) established internationally recognized definitions related to clinical practice, research, and policy. The 2017 edition comprised 283 terms and, among many others, expanded the concept of infertility to include not only its recognition as a disease, but also as an impairment of function generating disability. The glossary has been extensively used worldwide and has contributed to international standardization of data collection, appropriate comparison of outcome measures, and provided a reference for all stakeholders including policy makers.

    STUDY DESIGN, SIZE, DURATION

    Under guidance of the organizing committee, 21 professionals from across the world, and representing expertise in different sub-specialties, formed five working groups: clinical definitions; outcome measures; embryology laboratory; clinical and laboratory andrology; and epidemiology, public health and gender related definitions. The definitions from the previous glossary were evaluated and new terms identified. All definitions were then reviewed by an international advisory panel of nine experts that evaluated the glossary from scientific, ethical, cultural, and policy perspectives.

    PARTICIPANTS/MATERIALS, SETTING, METHODS

    Between November 2024 and October 2025, periodical virtual meetings were held within and between working groups and the organizing committee. Following circulation of the first consensually agreed draft, a one-day in-person meeting with representatives of all working groups and members of the international advisory panel was held at ESHRE, June 2025. Most terms and definitions were discussed and agreed. In the absence of agreement, further discussions were held between the organizing committee, working group chairs and members of the advisory panel. It had been determined at the outset that final disagreement would be resolved via a two-third majority vote. All terms and definitions were, however, reached by consensus and adopted following a final round of review and approval by all authors.

    MAIN RESULTS AND THE ROLE OF CHANCE

    The glossary now includes 348 terms. Compared to the previous edition, 14 terms were deleted, numerous terms modified and 79 new terms were added. Modifications reflect current scientific knowledge, technological advancements, and inclusivity related to gender and family structures. Chance does not play a role, as all definitions are consensus-based.

    LIMITATIONS, REASONS FOR CAUTION

    Some terms may require future refinement as scientific knowledge evolves and societal contexts change. The glossary reflects consensus rather than empirical testing of all definitions.

    WIDER IMPLICATIONS OF THE FINDINGS

    This glossary provides a global reference for standardized terminology, supporting clinical care, research, international comparisons, policy making, patient communication, and reproductive health literacy.

    STUDY FUNDING/COMPETING INTEREST(S)

    Neither ICMART, responsible for conducting this project, nor any of the participants received specific financial support for their activities in this project. Ferring provided ICMART with a fixed amount to cover venue costs and a one-day hotel accommodation for participants attending the in-person meeting held prior to the ESHRE Congress in June 2025. Disclosures were provided by all authors, and none reported any conflict of interest related to this manuscript.

    TRIAL REGISTRATION NUMBER

    N/A.

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Most Popular Articles

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    Double trisomy in spontaneous miscarriages: cytogenetic and molecular approach

    Human Reproduction. April 2006: 21(4):958-966

    BACKGROUND

    Although single trisomy is the most common chromosomal abnormality observed within first trimester spontaneous abortions (SA) (>50%), double trisomy (DT) ranges from 0.21 to 2.8% in the literature. Since little is known about mechanisms underlying DT, we report the results of our experience with 517 SA, establishing parental origin and cell stage of non-disjunction when possible in DT cases, and making a revision of those previously reported.

    METHODS

    Cytogenetic analysis was performed in all aborted specimens. Quantitative fluorescent PCR (QF-PCR) and multiplex ligation-dependent probe amplification (MLPA) were performed in DT cases in order to assess parental origin and stage of error of aneuploidy in addition to its reliability in detecting aneuploidies.

    RESULTS

    Karyotyping was successful in 321 miscarriages; the rate of DT was 2.18%. Among the seven DT cases reported, three new combinations were found. Maternal origin was established for all DT SA analysed. Meiotic stage of error was presumed meiosis I (MI) for 48,XX+15+22 and 48,XX+8+21, meiosis II (MII) for 48,XXX+18, and MII and MI respectively for 48,XY+18+22. Molecular results agreed with cytogenetic results.

    CONCLUSIONS

    Similar maternal age-related mechanisms could be implicated in both single and double trisomy. Molecular techniques could be useful in diagnosing not only single but multiple aneuploidy and determining its origin. This will improve our knowledge about mechanisms underlying human aneuploidy, and enable appropiate genetic counselling.

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    Neonatal outcome in a Danish national cohort of 3438 IVF/ICSI and 10 362 non-IVF/ICSI twins born between 1995 and 2000

    Human Reproduction. February 2004: 19(2):435-441

    BACKGROUND

    In Denmark, one-third of twin pregnancies are the result of IVF/ICSI treatment. Limited data on neonatal outcome in IVF/ICSI twins are available in the literature.

    METHODS

    A register study was conducted on neonatal morbidity and mortality in a complete national twin cohort including all 3438 (3393 live-born) IVF/ICSI and 10 362 (10 239 live-born) non-IVF/ICSI twins born between 1995 and 2000. Twins were identified in the National Medical Birth Registry and dichotomized into IVF/ICSI and non-IVF/ICSI by cross-reference with the Danish IVF Registry. Data on neonatal morbidity and mortality were retrieved from the Danish Patient Registry and the Danish Registry of Causes of Deaths. In order to exclude monozygotic twins, sub-analyses on unlike-sex twins were conducted.

    RESULTS

    A birth weight discordance of >20% was observed in 20.6% of IVF/ICSI versus 15.7% of control twin pairs (P < 0.001). The risk of discordant birth weight >20% was OR 1.29 (95% CI 1.04–1.58) in unlike-sex IVF/ICSI twins versus control twins. The risk of delivery at <37 completed weeks and birth weight <2500 g was similar in the two cohorts; however, in unlike-sex IVF/ICSI versus control twins the risk of delivery at <37 weeks and birth weight <2500 g was OR 1.22 (95% CI 1.09–1.38) and OR 1.25 (1.11–1.40) respectively. After stratification for maternal age and parity, these risks disappeared. IVF/ICSI twins carried a higher risk of admittance to a neonatal intensive care unit (NICU) than control twins (OR 1.18, 95% CI 1.09–1.27), and this was even more pronounced in unlike-sex twins [OR 1.34 (95% CI 1.19–1.51)]. No differences were observed in malformation or mortality rates between the two cohorts.

    CONCLUSIONS

    Despite higher birth weight discordance and more NICU admissions among IVF/ICSI twins, neonatal outcome in IVF/ICSI twins seems to be comparable with that of non-IVF/ICSI twins, when only dizygotic twins were considered in the comparisons.

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