The International Glossary on Infertility and Fertility Care, 2025†.

Terms and definitions used in infertility and fertility care continue to evolve alongside rapid scientific progress and societal change. Clear, scientifically accurate, and internationally agreed terminology and definitions matter for many reasons. They facilitate the collection and comparison of scientific data nationally, regionally, and internationally. They are central for the scientific communication related to procedures and their outcomes to patients, health care providers, policy makers, and the wider public. Furthermore, they carry weight in shaping societal acceptance. For example, how the international scientific community defines an embryo, informed by the science of developmental biology, or defines infertility, not only guides scientific discourse but also influences legislation, policy making, funding priorities, and the promotion and protection of reproductive health and rights, especially for women and men suffering from infertility ( Starrs et al ., 2018 ; Fauser et al ., 2024 ). Lastly, they help to counter the current epidemic of misinformation and disinformation which, though having many drivers, thrives in the presence of ambiguity. The first internationally standardized set of 53 definitions was published in 2006 by the International Committee for Monitoring Assisted Reproductive Technologies (ICMART) as The ICMART Glossary on ART Terminology ( Zegers-Hochschild et al ., 2006a , b ). In 2009, a revised edition including 87 definitions was published following an international consensus process led by ICMART in collaboration with the World Health Organization (WHO). This 2nd edition, now known as the WHO Glossary on Infertility , defined infertility for the first time as a disease of the reproductive system; a recognition and designation with wide-reaching social, legal, and financial implications ( Zegers-Hochschild et al ., 2009a , b ). The most recent edition, the International Glossary on Infertility and Fertility Care , 2017, comprising 283 definitions, was again published under the leadership of ICMART, in partnership with all major international organizations in the field ( Zegers-Hochschild et al ., 2017a , b ). In the 2017 edition, the definition of infertility was expanded in order to also recognize infertility as an impairment of function, thus widening the definition of infertility and bringing infertile persons and couples without a disease, as well as individuals and same sex couples under its umbrella. Many other terms were introduced for the first time, such as fertility awareness and fertility care, which are now used extensively in social science research. Today, major advances in science and technology have reshaped both clinical practice and research. The use of new terminology in areas such as preimplantation genetic testing, whole-genome sequencing, and innovative methods for gamete and embryo assessment, require standardized definitions allowing for a proper evaluation of such procedures as well as the possibility of conducting national and international comparisons. Similarly, from a social science perspective, increasing access to fertility treatments by gender-diverse individuals requires new definitions which need to be precise, inclusive, and culturally accepted. Definitions that once assumed a binary, heteronormative framework are no longer sufficient to guide practice or policy in an era where reproductive autonomy and equity are central to human health and rights ( World Health Organization, 2025 ). In this glossary on the science and biology of human reproduction, the terms female and male are used to refer to the biological sex, while recognizing that there is further biological diversity of sex. The words woman/women are used to refer to cisgender women (women born female and identifying as women) as well as gender-diverse persons with female reproductive organs, while equally recognizing all women in their biological and gender diversity. The words man/men are used to refer to cisgender men (men born male and identifying as men) as well as gender-diverse persons with male reproductive organs, while equally recognizing all men in their biological and gender diversity. We refer to a couple as two persons jointly intending to have a child, while acknowledging that some persons may be single parents and that some relationships may involve more than one partner. This new edition of the International Glossary on Infertility and Fertility Care aims to provide an authoritative, evidence-based, and inclusive set of terms and definitions, aligned with the science and social needs of contemporary fertility care, and to continue harmonizing communication across disciplines and geographical regions.

This fourth edition of the International Glossary on Infertility and Fertility Care contains 348 terms and their definitions which are listed in alphabetical order. Between the 3rd and the current edition, numerous terms were modified to reflect current knowledge and use of language; 14 terms were deleted and 79 new terms were incorporated. The International Glossary on Infertility and Fertility Care, 2025 The total number of deliveries with at least one live birth resulting from one initiated or aspirated ART cycle, including all cycles in which fresh and/or frozen embryos are transferred, including more than one delivery from one initiated or aspirated cycle if that occurs, until all embryos are used. Notes: The delivery of a singleton, twin, or other multiple pregnancy is MAR/ART registered as one delivery. In the absence of complete data, the total delivery rate is often estimated.

The development of this glossary followed a similar methodology as previous editions ( Zegers-Hochschild et al ., 2009a , b , 2017a , b ). Briefly, a structured, consensus-driven process designed to ensure scientific accuracy, inclusivity, and cultural sensitivity was implemented by ICMART. This process commenced with the invitation and appointment of two chairs for each of five working groups. In conjunction with these ten chairs, other leading experts in their field were invited to join, resulting in 21 experts with a maximum of five professionals per working group ( Table 1 ). Some chairs and members had participated in the 2017 glossary edition, thus ensuring continuity, while others were new to this work. The working groups covered the following areas: (1) clinical definitions, (2) laboratory embryology, (3) clinical and laboratory andrology, (4) outcome measures and (5) epidemiology, public health, and gender-related terminology applicable to reproduction. Working group and International advisory panel members. ICMART, International Committee for Monitoring Assisted Reproductive Technologies. Led by the chairs, the working groups reviewed all definitions from the 2017 edition, deleting when relevant, recommending modifications where needed, and proposing new definitions in response to advances in science, clinical practice, and societal needs. Furthermore, special effort was made to ensure consistency with definitions already addressed by the World Health Organization (WHO) and included in the International Classification of Diseases (ICD-11). Between November 2024 and June 2025, periodical virtual meetings were held within each working group and between individual working groups and the organizing committee. Some of these virtual meetings included members from all working groups. All terms and definitions were then reviewed by an international advisory panel (IAP) comprising nine experts with global geographic distribution and representing most international and regional organizations responsible for infertility and fertility care ( Table 1 ). Their role was to evaluate each term not only from a scientific perspective but also to consider ethical, cultural, and policy implications. Subsequently, a one-day, in-person meeting was held at the 2025 ESHRE annual meeting with representatives of all working groups, the organizing committee, and members of the IAP. Each working group chair or representative presented their new terminologies as well as those which had been flagged for discussion by the advisory panel or the working group itself. In this manner, most of the meeting was utilized to discuss the more challenging terms and reach consensus. A few terms for which consensus could not be reached were flagged for further work and discussion together with addressing additional input from the advisory panel. Although it had been determined at the outset that any final disagreement would be resolved via a two-third majority vote, all definitions were ultimately reached by consensus. In September 2025, a pre-final document was distributed to all working group members and the advisory panel for acceptance or final comments. This feedback was incorporated upon which the final document for publication was generated and sent for review and endorsement by patient organizations. This entire process was coordinated and overseen by the ICMART organizing committee, which facilitated communication across the working groups, consolidated revisions, and ensured alignment with the glossary’s overarching aims.

This fourth edition of the International Glossary on Infertility and Fertility Care highlights and simultaneously addresses the continuing need for precise, inclusive, and globally agreed terminology in a rapidly evolving field. The definitions presented here were developed by consensus through multiple rounds of written feedback, virtual and in-person meetings, and open discussion, in a process that was designed to balance scientific rigour with inclusivity. In this way, the glossary reflects both the most current knowledge in reproductive science and the diversity of cultural and social contexts in which these terms will be applied. Advances in reproductive science and the continuous integration of new technologies into clinical practice require ongoing, systematic, and objective evaluation. This encompasses broader societal changes including the growing demands for family building among gender-diverse individuals. Collectively, such evaluation often depends on the analysis of large datasets, which only achieve their full value when built upon standardized definitions. This glossary addresses these developments by revising existing terms and introducing new ones with careful attention to global inclusivity and diversity. Furthermore, by harmonizing language across regions and disciplines, this glossary facilitates international data collection and interpretation, as well as scientific exchange. We anticipate that this revised glossary will continue to serve as a global reference, strengthen international dialogue, and contribute to infertility and its interventions being monitored and reported in a standardized way, practiced with scientific rigour, and provided with cultural sensitivity and respect for diversity. It is our hope that it will also inform policy making as well as reproductive health education and health literacy among the public and patients who need to make reproductive decisions.