The International Glossary on Infertility and Fertility Care

The following glossary was developed in 2017 by a global panel of more than 100 multidisciplinary experts, professional organisations, and patient representatives to provide consensus agreement on 283 items and definitions. Published in Fertility and Sterility (FNS) and Human Reproduction (HR).

A printable version of the 2017 Glossary and more information on the methodology, and a list of previous compiled glossaries can be found here.




Early neonatal death/mortality

Death of a newborn within 7 days of birth.

Ectopic pregnancy

A pregnancy outside the uterine cavity, diagnosed by ultrasound, surgical visualization or histopathology.


Co-ordinated contractions of the genitourinary tract leading to the ejection of spermatozoa and seminal fluid.

Ejaculation retardata

A condition resulting in an inability to ejaculate during vaginal intercourse.

Ejaculatory duct

The canal that passes through the prostate just lateral to the verumontanum where the vas deferens and the duct from the seminal vesicle coalesce.

Elective embryo transfer

The transfer of one or more embryos, selected from a larger cohort of available embryos.

Elective single embryo transfer (eSET)

The transfer of one (a single) embryo selected from a larger cohort of available embryos.


The biological organism resulting from the development of the zygote, until eight completed weeks after fertilization, equivalent to 10 weeks of gestational age.

Embryo bank

Repository of cryopreserved embryos stored for future use.

Embryo donation (for reproduction)

An ART cycle, which consists of the transfer of an embryo to the uterus or Fallopian tube of a female recipient, resulting from gametes that did not originate from the female recipient or from her male partner, if present.

Embryo fragmentation

The process during which one or more blastomeres shed membrane vesicles containing cytoplasm and occasionally whole chromosomes or chromatin.

Embryo recipient cycle

An ART cycle in which a woman's uterus is prepared to receive one or more cleavage stage embryos/blastocysts, resulting from gametes that did not originate from her or from her male partner, if present.

Embryo transfer (ET)

Placement into the uterus of an embryo at any embryonic stage from day 1 to day 7 after IVF or ICSI. Embryos from day 1 to day three can also be transferred into the Fallopian tube.

Embryo transfer cycle

An ART cycle in which one or more fresh or frozen/thawed embryos at cleavage or blastocyst stage are transferred into the uterus or Fallopian tube.

Emission (semen)

Co-ordinated contractions of the vas deferentia, seminal vesicles, and ejaculatory ducts leading to deposition of semen into the urethral meatus prior to ejaculation.


A disease characterized by the presence of endometrium-like epithelium and stroma outside the endometrium and myometrium. Intrapelvic endometriosis can be located superficially on the peritoneum (peritoneal endometriosis), can extend 5 mm or more beneath the peritoneum (deep endometriosis) or can be present as an ovarian endometriotic cyst (endometrioma).


A convoluted, highly coiled duct that transports the spermatozoa from the testis via the efferent ducts to the vas deferens.

Erectile dysfunction

Inability to have and/or sustain an erection sufficient for intercourse.


The condition in which a cell has chromosomes in an exact multiple of the haploid number; in the human this multiple is normally two. Thus, a normal embryo that is euploid is also diploid.

Excessive ovarian response

An exaggerated response to ovarian stimulation characterized by the presence of more follicles than intended. Generally, more than 20 follicles >12 mm in size and/or more than 20 oocytes collected following ovarian stimulation are considered excessive, but these numbers are adaptable according to ethnic and other variables.

Expectant fertility management

Management of fertility problems including infertility without any specific active clinical or therapeutic interventions other than fertility information and advice, to improve natural fertility, based upon the probability of becoming pregnant.

Extremely low birth weight

Birth weight less than 1000 g.

Extremely preterm birth

A birth that takes place after 22 but before 28 completed weeks of gestational age.



The probability of a pregnancy, during a single menstrual cycle in a woman with adequate exposure to sperm and no contraception, culminating in a live birth. In population-based studies, fecundability is frequently measured as the monthly probability.


Clinically defined as the capacity to have a live birth.

Female infertility

Infertility caused primarily by female factors encompassing: ovulatory disturbances; diminished ovarian reserve; anatomical, endocrine, genetic, functional or immunological abnormalities of the reproductive system; chronic illness; and sexual conditions incompatible with coitus.


The capacity to establish a clinical pregnancy.

Fertility awareness

The understanding of reproduction, fecundity, fecundability, and related individual risk factors (e.g. advanced age, sexual health factors such as sexually transmitted infections, and life style factors such as smoking, obesity) and non-individual risk factors (e.g. environmental and work place factors); including the awareness of societal and cultural factors affecting options to meet reproductive family planning, as well as family building needs.

Fertility care

Interventions that include fertility awareness, support and fertility management with an intention to assist individuals and couples to realize their desires associated with reproduction and/or to build a family.

Fertility preservation

Various interventions, procedures and technologies, including cryopreservation of gametes, embryos or ovarian and testicular tissue to preserve reproductive capacity.


A sequence of biological processes initiated by entry of a spermatozoon into a mature oocyte followed by formation of the pronuclei.

Fetal loss

Death of a fetus. It is referred to as early fetal loss when death takes place between 10 and 22 weeks of gestational age; late fetal loss, when death takes place between 22 and 28 weeks of gestational age; and stillbirth when death takes place after 28 weeks gestational age.


The stages of development of an organism from eight completed weeks of fertilization (equivalent to 10 weeks of gestational age) until the end of pregnancy.

Freeze-all cycle

An ART cycle in which, after oocyte aspiration, all oocytes and/or embryos are cryopreserved and no oocytes and/or embryos are transferred to a woman in that cycle.

Frozen-thawed embryo transfer (FET) cycle

An ART procedure in which cycle monitoring is carried out with the intention of transferring to a woman, frozen/thawed or vitrified/warmed embryo(s)/blastocyst(s). Note: A FET cycle is initiated when specific medication is provided or cycle monitoring is started in the female recipient with the intention to transfer an embryo.

Frozen-thawed oocyte cycle

An ART procedure in which cycle monitoring is carried out with the intention of fertilizing thawed/warmed oocytes and performing an embryo transfer.

Full-term birth

A birth that takes place between 37 and 42 completed weeks of gestational age.


Gamete intrafallopian transfer (GIFT)

An ART procedure in which both gametes (oocytes and spermatozoa) are transferred into a Fallopian tube(s).

Germinal vesicle (GV)

The nucleus in an oocyte at prophase I.

Gestational age

The age of an embryo or fetus calculated by the best obstetric estimate determined by assessments which may include early ultrasound and the date of the last menstrual period and/or perinatal details. In the case of ART, it is calculated by adding two weeks (14 days) to the number of completed weeks since fertilization. Note: For frozen-thawed embryo transfer (FET) cycles, an estimated date of fertilization is computed by subtracting the combined number of days an embryo was in culture pre-cryopreservation and post-thaw/-warm, from the transfer date of the FET cycle.

Gestational carrier

A woman who carries a pregnancy with an agreement that she will give the offspring to the intended parent(s). Gametes can originate from the intended parent(s) and/or a third party (or parties). This replaces the term ‘surrogate.’

Gestational sac

A fluid-filled structure associated with early pregnancy, which may be located inside or, in the case of an ectopic pregnancy, outside the uterus.


Describes spermatozoa with a reduced or absent acrosome.



The condition in which a cell has one set of each of the 23 single chromosomes. Mature human gametes are haploid, each having 23 single chromosomes.


The process by which an embryo at the blastocyst stage extrudes out of, and ultimately separates from, the zona pellucida.

Heterotopic pregnancy

Concurrent pregnancy involving at least one embryo implanted in the uterine cavity and at least one implanted outside of the uterine cavity.

High-order multiple births

The complete expulsion or extraction from their mother of three or more fetuses, after 22 completed weeks of gestational age, irrespective of whether they are live births or stillbirths.

High-order multiple gestation

A pregnancy with three or more embryos or fetuses.


A distally occluded, dilated, fluid-filled Fallopian tube.

Hypergonadotropic hypogonadism

Gonadal failure associated with reduced gametogenesis, reduced gonadal steroid production and elevated gonadotropin production.


High volume of ejaculate above the upper reference limit. When reporting results, the reference criteria should be specified.

Hypogonadotropic hypogonadism

Gonadal failure associated with reduced gametogenesis and reduced gonadal steroid production due to reduced gonadotropin production or action.


Histopathologic description of reduced production of spermatozoa in the testes.


Low volume of ejaculate below the lower reference limit. When reporting results, the reference criteria should be specified.