International Committee for Monitoring Assisted Reproductive Technology (ICMART) and the World Health Organization (WHO) revised glossary of ART terminology, 2009
(Professor Nargund was a member of this committee in her capacity as President of ISMAAR)
Assisted reproductive technology (ART): all treatments or procedures that include the in vitro handling of both human oocytes and sperm or of embryos for the purpose of establishing a pregnancy. This includes, but is not limited to, in vitro fertilization and embryo transfer, gamete intrafallopian transfer, zygote intrafallopian transfer, tubal embryo transfer, gamete and embryo cryopreservation, oocyte and embryo donation, and gestational surrogacy. ART does not include assisted insemination (artificial insemination) using sperm from either a woman’s partner or a sperm donor.
Biochemical pregnancy (preclinical spontaneous abortion/miscarriage): a pregnancy diagnosed only by the detection of hCG in serum or urine and that does not develop into a clinical pregnancy.
Blastocyst: an embryo, 5 or 6 days after fertilization, with an inner cell mass, outer layer of trophectoderm, and a fluid-filled blastocele cavity.
Cancelled cycle: an ART cycle in which ovarian stimulation or monitoring has been carried out with the intention to treat, but which did not proceed to follicular aspiration or, in the case of a thawed embryo, to embryo transfer.
Clinical pregnancy: a pregnancy diagnosed by ultrasonographic visualization of one or more gestational sacs or definitive clinical signs of pregnancy. It includes ectopic pregnancy. Note: Multiple gestational sacs are counted as one clinical pregnancy.
Clinical pregnancy rate: the number of clinical pregnancies expressed per 100 initiated cycles, aspiration cycles, or embryo transfer cycles. Note: When clinical pregnancy rates are given, the denominator (initiated, aspirated, or embryo transfer cycles) must be specified.
Clinical pregnancy with fetal heart beat: pregnancy diagnosed by ultrasonographic or clinical documentation of at least one fetus with heart beat. It includes ectopic pregnancy.
Congenital anomalies: all structural, functional, and genetic anomalies diagnosed in aborted fetuses, at birth, or in the neonatal period.
Controlled ovarian stimulation (COS) for ART: pharmacologic treatment in which women are stimulated to induce the development of multiple ovarian follicles to obtain multiple oocytes at follicular aspiration.
Controlled ovarian stimulation (COS) for non-ART cycles: pharmacologic treatment for women in which the ovaries are stimulated to ovulate more than one oocyte.
Cryopreservation: the freezing or vitrification and storage of gametes, zygotes, embryos, or gonadal tissue
Cumulative delivery rate with at least one live born baby: the estimated number of deliveries with at least one live born baby resulting from one initiated or aspirated ART cycle including the cycle when fresh embryos are transferred and subsequent frozen/thawed ART cycles. This rate is used when less than the total number of embryos fresh and/or frozen/thawed have been used from one ART cycle. Note: The delivery of a singleton, twin, or other multiple pregnancy is registered as one delivery.
Delivery: the expulsion or extraction of one or more fetuses from the mother after 20 completed weeks of gestational age.
Delivery rate after ART treatment per patient: the number of deliveries with at least one live born baby per patient after a specified number of ART treatments.
Delivery rate: the number of deliveries expressed per 100 initiated cycles, aspiration cycles, or embryo transfer cycles. When delivery rates are given, the denominator (initiated, aspirated, or embryo transfer cycles) must be specified. It includes deliveries that resulted in the birth of one or more live babies and/or stillborn babies. Note: The delivery of a singleton, twin, or other multiple pregnancy is registered as one delivery.
Early neonatal death: death of a live born baby within 7 days of birth.
Ectopic pregnancy: a pregnancy in which implantation takes place outside the uterine cavity.
Elective embryo transfer: the transfer of one or more embryos, selected from a larger cohort of available embryos.
Embryo: the product of the division of the zygote to the end of the embryonic stage, 8 weeks after fertilization. (This definition does not include either parthenotes—generated through parthenogenesis—nor products of somatic cell nuclear transfer.)
Embryo donation: the transfer of an embryo resulting from gametes (spermatozoa and oocytes) that did not originate from the recipient and her partner.
Embryo recipient cycle: an ART cycle in which a woman receives zygote(s) or embryo(s) from donor(s).
Embryo/fetus reduction: a procedure to reduce the number of viable embryos or fetuses in a multiple pregnancy.
Embryo transfer (ET): the procedure in which one or more embryos are placed in the uterus or fallopian tube.
Embryo transfer cycle: an ART cycle in which one or more embryos are transferred into the uterus or fallopian tube.
Extremely low birth weight: birth weight less than 1,000g.
Extremely preterm birth: a live birth or stillbirth that takes place after 20 but before 28 completed weeks of gestational age.
Fertilization: the penetration of the ovum by the spermatozoon and combination of their genetic material resulting in the formation of a zygote.
Fetal death (stillbirth): death before the complete expulsion or extraction from its mother of a product of fertilization, at or after 20 completed weeks of gestational age. The death is indicated by the fact that, after such separation, the fetus does not breathe or show any other evidence of life, such as heart beat, umbilical cord pulsation, or definite movement of voluntary muscles.
Fetus: the product of fertilization from completion of embryonic development, at 8 completed weeks after fertilization, until abortion or birth.
Frozen-thawed embryo transfer cycle (FET): an ART procedure in which cycle monitoring is carried out with the intention of transfering frozen-thawed embryo(s). Note: An FET cycle is initiated when specific medication is provided or cycle monitoring is started with the intention to treat.
Frozen-thawed oocyte cycle: an ART procedure in which cycle monitoring is carried out with the intention of fertilizing thawed oocytes and performing embryo transfer.
Full-term birth: a live birth or stillbirth 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 to the fallopian tube.
Gestational age: age of an embryo or fetus calculated by adding 2 weeks (14 days) to the number of completed weeks since fertilization. Note: For frozen-thawed embryo transfers, an estimated date of fertilization is computed by subtracting the embryo age at freezing from the transfer date of the FET cycle.
Gestational carrier (surrogate): 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).
Gestational sac: a fluid-filled structure associated with early pregnancy, which may be located inside or outside the uterus (in case of an ectopic pregnancy).
Hatching: the process by which an embryo at the blastocyst stage separates from the zona pellucida.
High-order multiple: a pregnancy or delivery with three or more fetuses or neonates.
Implantation: the attachment and subsequent penetration by the zona-free blastocyst (usually in the endometrium) that starts 5 to 7 days after fertilization.
Implantation rate: the number of gestational sacs observed divided by the number of embryos transferred.
In vitro fertilization (IVF): an ART procedure that involves extracorporeal fertilization.
Induced abortion: the termination of a clinical pregnancy by deliberate interference that takes place before 20 completed weeks of gestational age (18 weeks after fertilization) or, if gestational age is unknown, of an embryo/fetus of less than 400 g.
Infertility (clinical definition): a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse.
Initiated cycle: an ART cycle in which the woman receives specific medication for ovarian stimulation, or monitoring in the case of natural cycles, with the intention to treat, irrespective of whether or not follicular aspiration is attempted.
Intracytoplasmic sperm injection (ICSI): a procedure in which a single spermatozoon is injected into the oocyte cytoplasm.
Live birth: the complete expulsion or extraction from its mother of a product of fertilization, irrespective of the duration of the pregnancy, which, after such separation, breathes or shows any other evidence of life, such as heart beat, umbilical cord pulsation, or definite movement of voluntary muscles, irrespective of whether the umbilical cord has been cut or the placenta is attached.
Live birth delivery rate: the number of deliveries that resulted in at least one live born baby, expressed per 100 initiated cycles, aspiration cycles, or embryo transfer cycles. When delivery rates are given, the denominator (initiated, aspirated, or embryo transfer cycles) must be specified.
Low birth weight: Birth weight less than 2,500g.
Medically assisted reproduction (MAR): reproduction brought about through ovulation induction, controlled ovarian stimulation, ovulation triggering, ART procedures, and intrauterine, intracervical, and intravaginal insemination with semen of husband/partner or donor.
MESA: microsurgical epididymal sperm aspiration.
MESE: microsurgical epididymal sperm extraction.
Micromanipulation: a technology that allows micro-operative procedures to be performed on the spermatozoon, oocyte, zygote, or embryo.
MicroTESE: Microsurgical testicular sperm extraction.
Mild ovarian stimulation for IVF: a procedure in which the ovaries are stimulated with gonadotropins and/or other compounds, with the intent to limit the number of oocytes obtained for IVF to fewer than seven.
Missed abortion: a clinical abortion where the embryo(s) or fetus(es) is/are nonviable and is/are not expelled spontaneously from the uterus.
Modified natural cycle: an IVF procedure in which one or more oocytes are collected from the ovaries during a spontaneous menstrual cycle. Drugs are administered with the sole purpose of blocking the spontaneous LH surge and/or inducing final oocyte maturation.
Multiple gestation/birth: a pregnancy/delivery with more than one fetus/neonate.
Natural cycle IVF: an IVF procedure in which one or more oocytes are collected from the ovaries during a spontaneous menstrual cycle without any drug use.
Neonatal death: death of a live born baby within 28 days of birth.
Neonatal period: the time interval that commences at birth and ends 28 completed days after birth.
Oocyte donation cycle: a cycle in which oocytes are collected from a donor for clinical application or research.
Oocyte recipient cycle: an ART cycle in which a woman receives oocytes from a donor.
Ovarian hyperstimulation syndrome (OHSS): an exaggerated systemic response to ovarian stimulation characterized by a wide spectrum of clinical and laboratory manifestations. It is classified as mild, moderate, or severe according to the degree of abdominal distention, ovarian enlargement, and respiratory, hemodynamic, and metabolic complications.
Ovarian torsion: partial or complete rotation of the ovarian vascular pedicle that causes obstruction to ovarian blood flow, potentially leading to necrosis of ovarian tissue.
Ovulation induction (OI): pharmacologic treatment of women with anovulation or oligo-ovulation with the intention of inducing normal ovulatory cycles.
Perinatal mortality: fetal or neonatal death occurring during late pregnancy (at 20 completed weeks of gestational age and later), during childbirth, or up to 7 completed days after birth.
PESA: percutaneous epididymal sperm aspiration.
Post-term birth: a live birth or stillbirth that takes place after 42 completed weeks of gestational age.
Preimplantation genetic diagnosis (PGD): analysis of polar bodies, blastomeres, or trophectoderm from oocytes, zygotes, or embryos for the detection of specific genetic, structural, and/or chromosomal alterations.
Preimplantation genetic screening (PGS): analysis of polar bodies, blastomeres, or trophectoderm from oocytes, zygotes, or embryos for the detection of aneuploidy, mutation, and/or DNA rearrangement.
Preterm birth: a live birth or stillbirth that takes place after at least 20 but before 37 completed weeks of gestational age.
Recurrent spontaneous abortion/miscarriage: the spontaneous loss of two or more clinical pregnancies.
Reproductive surgery: surgical procedures performed to diagnose, conserve, correct, and/or improve reproductive function.
Severe ovarian hyperstimulation syndrome: severe OHSS is defined to occur when hospitalization is indicated. (See definition of ‘‘ovarian hyperstimulation syndrome.’’)
Small for gestational age: birth weight less than 2 standard deviations below the mean or less than the 10th percentile according to local intrauterine growth charts.
Sperm recipient cycle: an ART cycle in which a woman receives spermatozoa from a donor who is not her partner.
Spontaneous abortion/miscarriage: the spontaneous loss of a clinical pregnancy before 20 completed weeks of gestational age (18 weeks after fertilization) or, if gestational age is unknown, the loss of an embryo/fetus of less than 400g.
TESA: testicular sperm aspiration.
TESE: testicular sperm extraction.
Total delivery rate with at least one live birth: the estimated total number of deliveries with at least one live born baby resulting from one initiated or aspirated ART cycle including all fresh cycles and all frozen-thawed ART cycles. This rate is used when all of the embryos—fresh and/or frozen-thawed—have been used from one ART cycle. Note: The delivery of a singleton, twin, or other multiple pregnancy is registered as one delivery.
Vanishing sac(s) or embryo(s): spontaneous disappearance of one or more gestational sacs or embryos in an ongoing pregnancy, documented by ultrasound.
Very low birth weight: Birth weight less than 1,500g.
Very preterm birth: a live birth or stillbirth that takes place after 20 but before 32 completed weeks of gestational age.
Vitrification: an ultra-rapid cryopreservation method that prevents ice formation within the suspension which is converted to a glass-like solid.
Zygote: a diploid cell resulting from the fertilization of an oocyte by a spermatozoon, which subsequently divides to form an embryo.
Zygote intrafallopian transfer (ZIFT): a procedure in which zygote(s) is/are transferred into the fallopian tube.