Terminology for In Vitro Fertilization (IVF)

The below is a new terminology for In Vitro Fertilization (IVF) as proposed by the International Society for Mild Approaches in Assisted Reproduction (ISMAAR) consensus group. Published in the journal of Human Reproduction, 2007.

Natural cycle IVF
The term Natural cycle IVF should be used when IVF is carried out with oocytes collected from a woman’s ovary or ovaries in a spontaneous menstrual cycle without administration of any medication at any time during the cycle.

Modified natural cycle IVF
When exogenous hormones or any drugs are used when IVF is being performed during a spontaneous cycle with the aim of collecting a naturally selected single oocyte but with a reduction in chance of cycle cancellation. This could include:
 (i) The use of human chorionic gonadotrophin (hCG)
(ii) The administration of gonadotrophin-releasing hormone (GnRH) antagonist

Mild IVF
When FSH or HMG is administered at lower doses, and/or for a shorter duration in a GnRH antagonist co-treated cycle, or when oral compounds (anti-estrogens, or aromatase inhibitors) are used  either alone or in combination with gonadotrophins. HCG injection and luteal support are also administered.

Conventional IVF
The following protocols can be considered:
(i) GnRH agonist is used for pituitary down-regulation followed by conventional doses of stimulation with FSH or hMG.
(ii) GnRH agonist is administered in a flare protocol with conventional doses of FSH or hMG.
(iii) GnRH antagonist is used with conventional doses and early start of FSH or hMG.

All of the above methods include the administration of hCG and luteal support.


The International Committee for Monitoring Assisted Reproduction Technology (ICMART) glossary on ART terminology

Fernando Zegers-Hochschild, K.-G. Nygren, G. David Adamson, Jacques de Mouzon, Paul Lancaster, Ragaa Mansour and Elizabeth Sullivan

on behalf of The International Committee Monitoring Assisted Reproductive Technologies


Aspiration cycle: Initiated ART cycle in which one or more follicles are punctured and aspirated irrespective of whether or not oocytes are retrieved.

Assisted hatching: An in vitro procedure in which the zona pellucida of an embryo (usually at eight-cell stage or a blastocyst) is perforated by chemical, mechanical or laser-assisted methods to assist separation of the blastocyst from the zona pellucida.

Assisted Reproductive Technology (ART): All treatments or procedures that include the in vitro handling of human oocytes and sperm or embryos for the purpose of establishing a pregnancy. This includes, but is not limited to, IVF and transcervical embryo transfer, gamete intra-Fallopian transfer, zygote intra-Fallopian 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 sperm donor.

Birth defect: Structural, functional or developmental abnormalities present at birth or later in life, due to genetic or non-genetic factors acting before birth.

Blastocyst: An embryo with a fluid-filled blastocele cavity (usually developing by 5 or 6 days after fertilization).

Cancelled cycle: An ART cycle in which ovarian stimulation or monitoring has been carried out with the intent of undergoing ART but which did not proceed to follicular aspiration or, in the case of a thawed embryo, to transfer.

Clinical abortion: An abortion of a clinical pregnancy which takes place between the diagnosis of pregnancy and 20 completed weeks’ gestational age.

Clinical pregnancy: Evidence of pregnancy by clinical or ultrasound parameters (ultrasound visualization of a gestational sac). It includes ectopic pregnancy. Multiple gestational sacs in one patient are counted as one clinical pregnancy.

Clinical pregnancy rate: number of clinical pregnancies expressed per 100 initiated cycles, aspiration cycles or embryo transfer cycles. When clinical pregnancy rates are given, the denominator (initiated, aspirated or embryo transfer cycles) must be specified.

Controlled ovarian hyperstimulation (COH): Medical treatment to induce the development of multiple ovarian follicles in order to obtain multiple oocytes at follicular aspiration.

Cryopreservation: Freezing and storage of gametes, zygotes or embryos.

Delivery rate: 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 a live birth and/or stillbirth. Note: The delivery of a singleton, twin or other multiple pregnancy is registered as one delivery.

Early neonatal death: Death occurring within the first 7 days after delivery.

Ectopic pregnancy: A pregnancy in which implantation takes place outside the uterine cavity.

Embryo: Product of conception from the time of fertilization to the end of the embryonic stage 8 weeks after fertilization (the term ‘pre-embryo’ or dividing conceptus has been replaced by embryo).

Embryo donation: The transfer of an embryo resulting from gametes that did not originate from the recipient or her partner.

Embryo transfer (ET): Procedure in which embryo(s) are placed in the uterus or Fallopian tube.

Embryo transfer cycle: ART cycle in which one or more embryos are transferred into the uterus or Fallopian tube.

Fertilization: The penetration of the ovum by the spermatozoon and fusion of genetic materials resulting in the development of a zygote.

Fetus: The product of conception starting from completion of embryonic development (at 8 completed weeks after fertilization) until birth or abortion.

Full-term birth: A birth that takes place at 37 or more completed weeks of gestational age. This includes both live births and stillbirths.

Gamete intra-Fallopian transfer (GIFT): ART procedure in which both gametes (oocytes and sperm) are transferred to the Fallopian tubes.

Gestational age: Age of an embryo or fetus calculated by adding 14 days (2 weeks) to the number of completed weeks since fertilization.

Gestational carrier: A woman in whom a pregnancy resulted from fertilization with third party sperm and oocytes. She carries the pregnancy with the intention or agreement that the offspring will be parented by one or both of the persons that produced the gametes.

Gestational sac: A fluid-filled structure containing an embryo that develops early in pregnancy usually within the uterus.

Hatching: Is the process that precedes implantation by which an embryo at the blastocyst stage separates from the zona pellucida.

Host uterus: See gestational carrier.

Implantation: The attachment and subsequent penetration by the zona-free blastocyst (usually in the endometrium) which starts 5-to-7 days following fertilization.

Infertility: Failure to conceive after at least 1 year of unprotected coitus.

Initiated cycles: ART treatment cycles in which the woman receives ovarian stimulation, or monitoring in the case of spontaneous cycles, irrespective of whether or not follicular aspiration was attempted.

Intracytoplasmic sperm injection (ICSI): IVF procedure in which a single spermatozoon is injected through the zona pellucida into the oocyte.

IVF: An ART procedure, which involves extracorporeal fertilization.

Live birth: A birth in which a fetus is delivered with signs of life after complete expulsion or extraction from its mother, beyond 20 completed weeks of gestational age. (Live births are counted as birth events, e.g. a twin or triplet live birth is counted as one birth event).

Live birth delivery rate: Number of live birth 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 at least one live birth. Note: The delivery of a singleton, twin or other multiple birth is registered as one delivery.

Malformation rate: Includes all structural, functional, genetic and chromosomal abnormalities identified in aborted tissue or diagnosed before or subsequent to birth.

Medically assisted conception: Conception brought about by non-coital conjunction of the gametes. Includes ART procedures and intrauterine, intracervical and intravaginal insemination with semen of husband/partner or donor.

Micromanipulation (also referred to as Assisted Fertilization): The use of special micromanipulative technology that allows operative procedures to be performed on the oocyte, sperm or embryo.

Microsurgical epididymal sperm aspiration (MESA): Procedure in which spermatozoa are obtained from the epididymis, by either aspiration or surgical excision.

Missed abortion: A clinical abortion where the products of conception are not expelled spontaneously from the uterus.

Neonatal death: Death within 28 days of birth.

New borns or infants born: The number of live births plus stillbirths.

Oocyte donation: An ART procedure performed with third-party oocytes.

Preclinical abortion: An abortion that takes place before clinical or ultrasound evidence of pregnancy.

Preclinical pregnancy (biochemical pregnancy): Evidence of conception based only on biochemical data in serum or urine before ultrasound evidence of a gestational sac.

Preimplantation genetic diagnosis (PGD): Screening of cells from preimplantation embryos for the detection of genetic and/or chromosomal disorders before embryo transfer.

Preterm birth: A birth which takes place after at least 20, but less than 37, completed weeks of gestation. This includes both live births and stillbirths. Births are counted as birth events (e.g. a twin or triplet live birth is counted as one birth event).

Recipient: In an ART cycle refers to the woman who receives an oocyte or an embryo from another woman.

Spontaneous abortion: Spontaneous loss of a clinical pregnancy before 20 completed weeks of gestation or, if gestational age is unknown, a weight of 500 g or less.

Stillbirth: A birth in which the fetus does not exhibit any signs of life when completely removed or expelled from the birth canal at or above 20 completed weeks of gestation. Stillbirths are counted as birth events (e.g. a twin or triplet stillbirth is counted as one birth event.

Surrogate mother: See gestational carrier.

Testicular sperm aspiration (TESA): Procedure in which spermatozoa are obtained directly from the testicle, by either aspiration or surgical excision of testicular tissue.

Zygote intra-Fallopian transfer (ZIFT): Procedure in which the zygote, in its pronuclear stage of development, is transferred into the Fallopian tube.

Zygote: Is the diploid cell resulting from the fertilization of an oocyte by a spermatozoon, which subsequently develops into an embryo.


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