Glossary of Terms

American Society for Reproductive Medicine (ASRM). Professional society whose affiliate organization, the Society for Assisted Reproductive Technology (SART), is composed of clinics and programs that provide ART.

ART (assisted reproductive technology). All treatments or procedures that include the handling of human eggs or embryos to help a woman become pregnant. ART includes, but is not limited to, in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), zygote intrafallopian transfer (ZIFT), tubal embryo transfer, egg and embryo cryopreservation (freezing), egg and embryo donation, and gestational surrogacy.

ART cycle. An ART cycle starts when a woman begins taking fertility drugs or having her ovaries monitored for follicle production. If eggs are produced, the cycle progresses to egg retrieval. Retrieved eggs are combined with sperm to create embryos. If fertilization is successful, at least one embryo is selected for transfer. If implantation occurs, the cycle may progress to clinical pregnancy and possibly live-birth delivery. ART cycles include any process in which (1) an ART procedure is performed, (2) a woman has undergone ovarian stimulation or monitoring with the intent of having an ART procedure, or (3) frozen embryos have been thawed with the intent of transferring them to a woman.

Canceled cycle. An ART cycle in which ovarian stimulation was performed but the cycle was stopped before eggs were retrieved or before embryos were transferred. Cycles are canceled for many reasons. For example, eggs may not develop, the patient may become ill, or the patient may choose to stop treatment.

Cryopreservation. The practice of freezing eggs or embryos from a patient’s ART cycle for potential future use.

Diminished ovarian reserve. This diagnosis means that the ability of the ovary to produce eggs is reduced. Reasons include congenital, medical, or surgical causes.

Donor egg cycle. An ART cycle in which an embryo is formed from the egg of one woman (the donor) and then transferred to another woman (the recipient). Sperm from either the recipient’s partner or a donor may be used.

Donated embryo cycle. An ART cycle in which an embryo that is donated by a patient or couple who previously underwent ART treatment and had extra embryos available is transferred to another woman (the recipient).

Ectopic pregnancy. A pregnancy in which the fertilized egg implants in a location outside of the uterus—usually in the fallopian tube, the ovary, or the abdominal cavity. Ectopic pregnancy is a dangerous condition that must receive prompt medical treatment.

Egg. A female reproductive cell, also called an oocyte or ovum.

Egg or Embryo banking cycle. An ART cycle started with the intent of freezing (cryopreserving) all resulting eggs or embryos for potential future use.

Egg retrieval (also called oocyte retrieval). A procedure to collect the eggs contained in the ovarian follicles.

Egg transfer (also called oocyte transfer). The transfer of retrieved eggs into a woman’s fallopian tubes through laparoscopy. This procedure is used only in gamete intrafallopian transfer (GIFT).

Embryo. An egg that has been fertilized by a sperm and has then undergone one or more cell divisions.

Embryo transfer. Placement of embryos into a woman’s uterus through the cervix after IVF. In zygote intrafallopian transfer (ZIFT) or gamete intrafallopian transfer (GIFT), zygotes or gametes are placed in a woman’s fallopian tube.

Endometriosis. A medical condition that involves the presence of tissue similar to the uterine lining in locations outside the uterus, such as the ovaries, fallopian tubes, or abdominal cavity.

Fertility Clinic Success Rate and Certification Act of 1992. Law passed by the US Congress in 1992 requiring all clinics performing ART in the United States to annually report their success rate data to the Centers for Disease Control and Prevention (CDC).

Fertility preservation cycle. An ART cycle started with the intent of freezing and banking all eggs or embryos for at least 12 months for future use.

Fertilization. The penetration of the egg by the sperm and the resulting combining of genetic material that develops into an embryo.

Fetus. The unborn offspring from the eighth week after conception to the moment of birth.

Follicle. A structure in the ovaries that contains a developing egg.

Fresh eggs, sperm, or embryos. Eggs, sperm, or embryos that have not been frozen.

Fresh embryo cycle. An ART cycle in which fresh (never frozen) embryos are transferred to the woman. The fresh embryos are conceived with fresh or frozen eggs and fresh or frozen sperm.

Frozen egg cycle. An ART cycle in which frozen (cryopreserved) eggs are thawed and fertilized, and then the resulting fresh embryo is transferred to the woman. Frozen and thawed eggs may be fertilized with either fresh or frozen sperm.

Frozen embryo cycle. An ART cycle in which frozen (cryopreserved) embryos are thawed and transferred to the woman. Frozen embryos may have been conceived using fresh or frozen eggs and fresh or frozen sperm.

Gamete. A reproductive cell, either a sperm or an egg.

Gestational age. The deviation of time from estimated last menstrual period (LMP) to birth. LMP is estimated using the date of retrieval or transfer.

Gestational carrier (also called a gestational surrogate). A woman who gestates, or carries, an embryo that was formed from the egg of another woman with the expectation of returning the infant to its intended parents.

Gestational sac. A fluid-filled structure that develops within the uterus early in pregnancy. In a normal pregnancy, a gestational sac contains a developing fetus.

GIFT (gamete intrafallopian transfer). An ART procedure that involves removing eggs from the woman’s ovary and using a laparoscope to place the unfertilized eggs and sperm into the woman’s fallopian tube through small incisions in her abdomen.

ICSI (intracytoplasmic sperm injection). A procedure in which a single sperm is injected directly into an egg; this procedure is commonly used to overcome male infertility problems.

Implantation rate. A measurement of ART success when the ART cycle results in an intrauterine clinical pregnancy, defined as the larger of either the maximum number of fetal hearts detected by ultrasound or the  maximum number of infants born, including live-birth deliveries and stillbirths, out of the total number of embryos transferred.

Infertility. In general, infertility refers to the inability to conceive after 12 months of unprotected intercourse. Women aged 35 or older who are unable to conceive after 6 months of unprotected intercourse generally are considered infertile for the purpose of initiating medical treatment.

IUI (intrauterine insemination). A medical procedure that involves placing sperm into a woman’s uterus to facilitate fertilization. IUI is not considered an ART procedure because it does not involve the manipulation of eggs.

IVF (in vitro fertilization). An ART procedure that involves removing eggs from a woman’s ovaries and fertilizing them outside her body. The resulting embryos are then transferred into a woman’s uterus through the cervix.

Live-birth delivery. The delivery of one or more infants with at least one born alive.

Male factor infertility. Any cause of infertility due to low sperm count or problems with sperm function that makes it difficult for a sperm to fertilize an egg under normal conditions.

Miscarriage (also called spontaneous abortion). A pregnancy ending in the spontaneous loss of the embryo or fetus before 20 weeks of gestation.

Multiple-fetus pregnancy. A pregnancy with two or more fetuses, determined by the number of fetal hearts observed on an ultrasound.

Multiple live-birth delivery. The delivery of more than one infant with at least one born alive.

National ART Surveillance System (NASS). Web-based data collection system used by all ART clinics to report data for each ART procedure to CDC.

Oocyte. The female reproductive cell, also called an egg.

Other reason, infertility. Reason for using ART that includes immunological problems, chromosomal abnormalities, cancer chemotherapy, and serious illnesses.

Other reason, non-infertility. Reason for using ART not related to infertility and not unexplained
or unknown.

Ovarian hyperstimulation syndrome. A possible complication of ovarian stimulation or ovulation induction that can cause enlarged ovaries, a distended abdomen, nausea, vomiting or diarrhea, fluid in the abdominal cavity or chest, breathing difficulties, changes in blood volume or viscosity, and diminished kidney perfusion and function.

Ovarian monitoring. The use of ultrasound or blood or urine tests to monitor follicle development and hormone production.

Ovarian stimulation. The use of drugs (oral or injected) to stimulate the ovaries to develop follicles
and eggs.

Ovulatory dysfunction. A diagnostic category used when a woman’s ovaries are not producing eggs normally. It is usually characterized by irregular menstrual cycles reflective of ovaries that are not producing one mature egg each month. It includes polycystic ovary syndrome and multiple ovarian cysts.

Patient (nondonor) cycle. An ART cycle in which an embryo is formed from the egg of the patient and either partner or donor sperm and then transferred back to the patient.

PGT (preimplantation genetic testing). Diagnostic or screening techniques performed on embryos before transfer to (1) detect specific genetic conditions to reduce the risk of passing inherited diseases to children or (2) screen for an abnormal number of chromosomes, which is of special value for patients with advanced age, recurrent miscarriages, or prior failed IVF.

Pregnancy (clinical). A pregnancy documented by ultrasound that shows a gestational sac in the uterus. For ART data-reporting purposes, pregnancy is defined as a clinical pregnancy rather than a chemical pregnancy (positive pregnancy test).

SET (single embryo transfer). Procedure in which one embryo, regardless of how many embryos are available, is placed in the uterus or fallopian tube. The embryo selected for SET might be a frozen (cryopreserved) embryo from a previous IVF cycle or a fresh embryo from the current fresh IVF cycle.

Singleton live-birth delivery. The delivery of a single infant born alive. Singleton live-birth delivery does not include the delivery of more than one infant with only one born alive.

Society for Assisted Reproductive Technology (SART). An affiliate of American Society for Reproductive Medicine (ASRM) composed of clinics and programs that provide ART.

Sperm. The male reproductive cell.

Spontaneous abortion. See Miscarriage.

Stillbirth. The birth of an infant that shows no sign of life after 20 or more weeks of gestation.

Stimulated cycle. An ART cycle in which a woman receives oral or injected fertility drugs to stimulate her ovaries to develop follicles that contain mature eggs.

Thawed embryo cycle. See frozen embryo cycle.

Tubal factor infertility. A diagnostic category used when the woman’s fallopian tubes are blocked or damaged, making it difficult for the egg to be fertilized or for an embryo to travel to the uterus.

Ultrasound. A technique used in ART for visualizing the follicles in the ovaries, the gestational sac, or the fetus.

Unexplained infertility. A diagnostic category used when no cause of infertility is found in either the woman or the man.

Unstimulated cycle. An ART cycle in which the woman does not receive drugs to stimulate her ovaries to produce more follicles and eggs. Instead, follicles and eggs develop naturally.

Uterine factor infertility. A structural or functional disorder of the uterus that results in reduced fertility.

ZIFT (zygote intrafallopian transfer). An ART procedure in which eggs are collected from a woman’s ovary and fertilized outside her body. A laparoscope is then used to place the resulting zygotes into the woman’s fallopian tube through a small incision in her abdomen.

Zygote. A fertilized egg before it begins to divide.