top of page


A | B | C | D | E | F | G | H | I | L | M | N | O | P | R | S | T | U | V | W | Z


American Society for Reproductive Medicine (ASRM)

A large multidisciplinary patient and physician organization serving as a platform for new ideas, education and advocacy in fertility and reproductive medicine issues. ASRM is a leading advocate for patient care, research and education. Their affiliate organization, the Society for Assisted Reproductive Technology (SART), is composed of clinics and programs that provide ART.



A condition, due to anovulation, in which a woman doesn't have menstrual periods. This condition is often associated with PCOS or problems with the hypothalamus and/or pituitary gland. Amenorrhea also occurs when a woman enters menopause.



When an egg has an abnormal number of chromosomes it is considered aneuploid. In the book, we refer to this as a low quality egg. Eggs with aneuploidies are the most common cause of miscarriage, particularly in early pregnancy.


Anti-Mullerian hormone (AMH)

A hormone produced by granulosa cells from maturing follicles. The more eggs a woman has, the more granulosa cells she has and the higher her level of AMH. According to Dr. Westphal, “We like to use AMH as a marker of a woman’s overall egg count. If the AMH is above 1.0, we feel relatively reassured, and if it’s less than 1.0, that is more concerning but it depends on the age of the woman. Of course, this will also correlate with a woman’s age, so a woman in her early 30s with a low AMH less than 1.0 is very worrisome, whereas it can be expected for women in her early 40s to have a low AMH.”

Antral Follicle Count (AFC)

An antral follicle count is performed by a doctor during an ultrasound. After visualizing the ovaries, the doctor can count the “activated” follicles, and use that number to estimate your total ovarian reserve.



A condition in which a woman doesn't ovulate or ovulates rarely.


Artificial Insemination

The general name for the procedure in which sperm are inserted directly into a woman's cervix, or, more commonly into the uterus. Most insemination is done into the uterus, “intrauterine insemination or IUI”.



The removal of fluid and cells by suction through a needle. This technique applies to many procedures in reproductive medicine, including egg freezing. Also commonly referred to as ‘egg retrieval’ or ‘egg harvesting.’


Assisted Reproductive Technology (ART)

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), tubal embryo transfer, egg and embryo cryopreservation, 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 follicles grow, 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. 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.



A human embryo after five to seven days of life, typically containing about 100 to 200 cells. This is the stage at which most embryos are biopsied for chromosome testing, frozen and/or transferred back to the patient.


Blastocyst Stage

Most IVF laboratories can grow embryos to the “blastocyst stage,” when the embryo has about a hundred cells and is more developed. The earlier an embryo reaches the blastocyst stage (often on day five), the quicker it grows and the healthier it may be. Embryos that develop to the blastocyst stage are more likely to lead to a live birth than cleavage stage embryos (four to eight cell embryos on day two or three of embryo culture). Approximately 50% of fertilized eggs make it to blastocyst stage, but that percentage can vary greatly from patient to patient and from one IVF cycle to another IVF cycle in the same patient. However, since it is easier to select the best embryos at the blastocyst stage, the transfer of one good quality blastocyst can yield better IVF success rates than would be the case following the transfer of earlier stage embryos. Moreover, by transferring fewer blastocysts, the fertility clinic can substantially reduce the risk of twins or even higher order multiple pregnancies.



Canceled Cycle

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


Cervical Mucus

Mucus produced by the cervix that increases in quantity as ovulation approaches. Near ovulation, cervical mucus becomes much more watery (less viscous), which allows sperm to swim from the vagina, up into the uterus and into the fallopian tubes, where the sperm meets and inseminates an egg.



The lower section of the uterus which protrudes into the vagina and serves as a reservoir for sperm. Its anatomical functions include being a natural barrier to the inner uterus, and also keeping pregnancies from delivering prematurely.



DNA and histone proteins are packaged into structures called chromosomes. Chromosomes are a key part of the process that ensures DNA is accurately copied and distributed in the vast majority of cell divisions. Still, mistakes do occur on rare occasions.


Chromosomal Abnormalities

Chromosomal abnormalities can occur as an accident when the egg or the sperm is initially formed or during the early developmental stages of the fetus. The age of the mother and/or certain other environmental factors may play a role in the occurrence of genetic errors. Chromosomal anomalies in eggs most commonly occur as an egg is getting ready to be ovulated, when it needs to expel exactly half of its 23 pairs of chromosomes, so sperm can bring in its 23 half sets to create a new unique human. As we get older, this process, especially in eggs and much less so in sperm, becomes much more faulty and this is the major mechanism for declining fertility with female age.



Division of one cell into 2, 2 into 4, 4 into 8, etc. This is measured in the embryology laboratory during IVF cycles.


Cleavage Stage

Once an egg has been fertilized, it will start to divide. After 2-3 days, the embryo will usually be 2-8 cells.  If it successfully passes through this stage, it moves to the morula and then the blastocyst stage.


Clinical Pregnancy

A pregnancy in which the beating fetal heart has been identified by ultrasound.


Congenital Anomaly

A non-hereditary characteristic, or defect, developed before birth. These can include very minor irregularities, such as curvature of the second toe so it overlaps the third toe, or can be a more major anomaly such as a heart defect.



The practice of freezing eggs, sperm or embryos from a patient’s ART cycle for potential future use. When biological material is frozen at a low enough temperature, all activity stops, including the activity leading to cell death or DNA degradation, and therefore the material is preserved. Vitrification is the cryopreservation method now used to freeze eggs and embryos.



In the world of reproductive medicine, “cycle” refers to one round of treatment. For example, an egg freezing cycle is a 2-3 week time period over which ovarian stimulation medication is taken and the doctor monitors progress. The cycle is completed once the eggs are retrieved. Cycle also refers to a woman’s menstrual cycle, the 24-35 days from the start of one menstrual bleed to the onset of the next menstrual bleed.



A fluid-filled structure. Cysts may be found anywhere in the body, but in reproductive medicine we primarily refer to them in the ovaries. Ovarian cysts may be normal or abnormal depending on the circumstances. Often they are just follicles that have not been fully reabsorbed from previous menstrual or treatment cycles. They are very common in both natural and stimulated cycles.


Diminished Ovarian Reserve (DOR)

This diagnosis means that the ability of the ovary to produce eggs is reduced. Reasons include congenital, medical or surgical causes or advanced age. Diminished ovarian reserve is not synonymous with whole body aging – it doesn’t mean that the woman herself is somehow aging prematurely, it just means her egg count overall is lower than it should be given her age. 


Donor Eggs

Eggs that are taken from one woman, fertilized and transferred into another woman. Usually egg donors must be between the ages of 18 and 35 years old. Occasionally, clinics might allow women older than that to donate to a family member.


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.


Donor 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).


Donor Insemination

The introduction of sperm from an anonymous or, less commonly, a known donor into the vagina, cervix, or uterine cavity in order to achieve a pregnancy.


Ectopic Pregnancy

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



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


Egg/Embryo Banking Cycle

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


Egg Donation

Egg donation involving the use of eggs donated by another woman who is typically in her 20s or early 30s. In an egg donation cycle, the woman receiving the donated eggs is referred to as the “recipient.” The egg donor receives fertility medications to stimulate the production of multiple eggs in her ovaries. The eggs are usually frozen, rather than transferred fresh. The egg recipient may get the eggs via a frozen donor egg bank. She is given hormone therapy to prepare her uterus to receive the fertilized eggs (embryos). After the eggs are obtained from the donor, they are fertilized in the laboratory with sperm from the recipient’s partner. Several days after fertilization, the embryos are transferred to the recipient’s uterus. Any embryos that are not transferred may be frozen (cryopreserved) for a future cycle. The high success rate with egg donation confirms that egg quality associated with age is the primary barrier to pregnancy in older women. If you are over 40, your chance of successful pregnancy is much higher in IVF cycles using donor eggs, but many couples or single women in their early 40s will choose to accept the lower chance of become pregnant and use their own eggs. By age 43, the chance of becoming pregnant through IVF is less than 5%, and by age 45, use of donor eggs is the only reasonable alternative.


Egg Retrieval (also called ‘Oocyte Retrieval’)

A procedure to collect the eggs contained in the ovarian follicles. Also see ‘Aspiration.’


Egg Quality

When an egg is considered genetically “normal” (euploid) vs. being abnormal (aneuploid).  Egg quality is difficult to determine but the best predictor is age.  As women age and the eggs inside their bodies are inevitably exposed to damaging influences, a higher and higher percentage of their eggs become abnormal. A high percentage of abnormal eggs can lead to infertility, miscarriage or genetic disorders such as Down syndrome. At this point in time, this testing can only be done on embryos, not eggs.


Egg Quantity

Egg quantity refers to the number of follicles, or potential eggs, in a woman’s ovaries. Though born with one to two million egg follicles, a woman loses upwards of 1,000 eggs per month until menopause, with the rate of loss increasing after 35. Low egg quantity can lead to infertility. Egg quantity for the purposes of setting expectations for egg freezing or IVF cycles with one’s own eggs is assessed with AMH blood test and AFC scan.



You may have noticed that neither of the editors are named ELANZA. So where does the name come from? The word ELANZA is a combination of two words. To do something with “élan” is to do it with purpose, grace and confidence – an approach that is reinforced throughout this book. The letters ZA create an acronym for the country of South Africa where Brittany and Catherine first became friends.



An embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell. The zygote possesses half the DNA from each of its two parents. The zygote will begin to divide by mitosis to produce a multicellular organism, which becomes an embryo. In human pregnancy, a developing fetus is considered an embryo until the ninth week, fertilization age, or eleventh week gestational age. After this time the embryo is referred to as a fetus.



A laboratory scientist with a specific focus on ART treatments. These individuals are responsible for eggs from the time of retrieval to the time when the embryo is implanted into the woman’s uterus. The embryologist is responsible for: maintaining the lab environment for the duration of the embryo's stay in the lab, ensuring that the lab environment mimics that of a woman’s uterus, inseminating the eggs to create embryos, freezing sperm, eggs and embryos, grading and observing the embryos, and performing laser biopsies on certain embryos to screen for genetic diseases.



The study of hormones and their function, the organs that produce them and how they are produced. Specialists in infertility are called Reproductive Endocrinologists.


Endometrial Biopsy

The extraction of a small piece of tissue from the endometrium (lining of the uterus) for pathologic examination. This is sometimes done when there have been repeated failures of normal embryos to implant.


Endometrial Cavity

The space inside the uterus that is created by the inner lining of the uterus that responds to female hormones during the menstrual and treatment cycles. This lining, when properly prepared, forms the area of attachment and implantation of the embryo. The uterus is commonly referred to as the womb.



A medical condition that involves the presence of tissue similar to the uterine lining in abnormal locations, usually in the pelvis, on the surface or inside the ovaries, and in the lining of the pelvis called the peritoneum. Endometriosis is strongly associated with infertility and many women who have it also have pelvic pain. IVF is often considered the best infertility treatment for endometriosis.



The tissue lining the inside of the uterus.



The principal hormone produced by the growing ovarian follicle. Its level is frequently measured via blood test to gauge the strength and development of your follicles during treatment cycles. Estradiol causes the endometrium to proliferate, preparing the uterus for implantation of an embryo.



The presence of the proper of chromosomes in an organism. Euploid eggs are genetically normal. See also ‘Egg Quality.’


European Society of Human Reproduction and Embryology (ESHRE)

A respected European-based society dedicated to promoting interest in, and understanding of, reproductive biology and medicine. ESHRE’s activities include teaching, training and professional accreditations, as well as developing and maintaining data registries. It also facilitates and disseminates research in human reproduction and embryology to the general public, scientists, clinicians and patient associations. ESHRE collaborates with politicians and policy makers throughout Europe.


Fallopian Tubes

The anatomic and physiologic connection between the uterus and the ovary which serves to transport the oocyte (egg) and sperm. It is also the site of fertilization and supports and transports the conceptus in route to the uterus.


Female Factor Infertility

Infertility due to ovulatory disturbances, diminished ovarian reserve, pelvic abnormalities affecting the reproductive tract such as endometriosis, or other abnormalities of the reproductive system.


Fertility Preservation

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



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



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



Overgrowth of the muscular tissue of the uterus. Fibroids are typically masses of benign muscle tissue that can distort the shape and function of the uterus. They are typically classified into three categories: submucosal, intramural and serosal. Submucosal fibroids are found in the uterine cavity and impair implantation. They need to be removed in order to conceive. Intramural fibroids are problematic when they become severely enlarged or impinge on the uterine cavity. Subserosal fibroids generally are left alone during fertility treatments unless they are very large. It is estimated that 70% of reproductive-age women have fibroids, most have no symptoms and don’t even know they have them unless they have a reason to have an ultrasound of the uterus.



A fluid-filled pocket in the ovary that houses the microscopic egg. Each ovary has many follicles within it. Follicles start out extremely small and then grow larger under the influence of hormones. Follicles are lined with granulosa cells that produce estrogen and nourish the oocyte (egg). Each follicle contains a single oocyte.


Follicular Phase

The menstrual cycle is divided up into two main parts- the follicular phase and the luteal phase. The follicular phase refers to the first half of the cycle, from the onset of menses to ovulation, and lasts approximately 14 days in a 28 days cycle. It is associated with developing follicles that produce estradiol. It is this phase that coincides with the injection phase of an egg freezing cycle.


Follicle Stimulation Hormone (FSH)

A hormone produced by the pituitary, an organ in the brain that encourages follicles and eggs to grow and mature each month. A recombinant form of it is also used in many ART procedures. Almost all manufactured forms of FSH are derived from human sources (e.g. the urine of post-menopausal women) and virtually identical to the FSH made by our pituitary gland.



folliculogenesis is the maturation of the ovarian follicle, a densely packed shell of somatic (non-gamete) cells that contains an immature oocyte, the gamete.


“Fresh” Eggs or Embryos

Eggs or embryos that have not been previously frozen.

Frozen Egg Cycle

An ART cycle in which frozen (cryopreserved) eggs are thawed, 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. Many times, frozen-thawed eggs are fertilized, cultured and then re-frozen as embryos for a subsequent frozen embryo transfer, especially in cases where patients wish to have their embryos tested for chromosome normality.


Frozen Embryo Cycle

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



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. Most gestational carriers carry pregnancies for women that don’t naturally or surgically have a womb, for women that have medical conditions that would put them at-risk for complications in pregnancy, and for homosexual male couples. Elective gestational surrogacy (because a woman just doesn’t want to be pregnant) would go against ASRM guidelines and is not done in most clinics.


Gonadotropin Releasing Hormone Agonist (GnRHa)

A hormone produced in the hypothalamus of the brain that is involved in triggering ovulation and when given daily, suppresses premature ovulation.


Gonadotropin Releasing Hormone Antagonists (GnRH Antagonist)

In egg retrieval cycles, these are commonly used to prevent premature ovulation.  A GnRH agonist can also be used as the final “trigger shot” before the egg retrieval. e.g. Cetrotide or Ganirelix. Protocols with GnRH antagonists are effective in preventing a premature rise of LH and induce a shorter and more cost-effective ovarian stimulation compared to the long agonist protocol.

Gonadotropin Releasing Hormone Agonists (GnRH Agonist)

e.g. Leuprolide. The combination of exogenous Gonadotropin plus a Gonadotropin Releasing Hormone (GnRH) agonist, is associated with increased pregnancy rate as compared with the use of gonadotropins without a GnRH agonist. A different synchronization of follicular recruitment and growth occurs with GnRH agonists than with GnRH antagonists.


Human Fertilisation and Embryology Authority (HFEA)

An executive non-departmental public body of the Department of Health and Social Care in the United Kingdom. HFEA regulates almost all aspects of ART in the UK.


Human Chorionic Gonadotropin (hCG)

A hormone of early pregnancy that is monitored to determine the viability of the gestation. This hormone is also introduced via injection to induce ovulation and maturation of the oocyte (egg) in ovarian stimulation protocols.


Human Menopausal Gonadotropin (hMG)

A purified extract of LH and FSH, the hormones secreted by the pituitary gland to stimulate the ovary. It is a commercial preparation used via injection to facilitate the development of multiple follicles in treatment cycles.



A portion of the brain that stimulates the pituitary gland to secrete LH and FSH in order to stimulate ovarian follicle development. The hypothalamus acts as the “pacemaker” for many important hormone-driven processes, controlling the production and periodic release of hormones from the pituitary gland.



Immature Oocyte

An oocyte that has not completed meiosis (an oocyte at the germinal vesicle (GV)-stage or metaphase 1 (M1) phase).


Impaired Fecundity

Difficulty getting pregnant or carrying a pregnancy to a live birth. This is generally considered the time prior to ‘infertility.’



The attachment and embedding of the embryo into the lining of the uterus.


Implantation Rate

The implantation rate is the number of fetal heartbeats seen on ultrasound divided by the number of embryos transferred. For example, if a patient has two embryos transferred and has one live embryo, the implantation rate is 50%.



In general, infertility refers to the inability to conceive after 12 months of unprotected intercourse, and in women aged 35 and older, the inability to conceive after six months of unprotected intercourse. Within the ART context, this is often used to describe couples that cannot get pregnant even with the help of fertility treatment, such as patients with tubal obstruction or male partners with zero sperm.


Intracytoplasmic Sperm Injection (ICSI)

A procedure in which a single sperm is injected directly into an egg; this procedure is commonly used to overcome male infertility problems and is the method used to fertilize thawed eggs.


Intrauterine Insemination (IUI) or Artificial Insemination (AI)

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.


In-Vitro Fertilization (IVF)

A procedure to help patients conceive pregnancies. IVF entails stimulating your ovaries to develop multiple follicles. This is achieved with injectable medications. The goal of IVF is to produce an increased number of growing follicles, then harvest the eggs inside the follicles through a short surgical procedure. The eggs are then inseminated with sperm in the laboratory, sometimes using ICSI, in order to create embryos that can then be transferred back to the endometrial cavity (the womb) of the patient. The name in vitro fertilization refers to the fact that the oocyte is fertilized by the sperm in the laboratory, rather than inside the female reproductive tract.


Live Birth

The delivery of one or more infants with any signs of life.


Low Birth Weight

Birth weight less than 2g.


Luteinizing Hormone

The hormone that triggers ovulation and is important in egg growth. In the male, it stimulates testosterone production and is important in the production of sperm cells.



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.


Mature Oocyte

An oocyte (egg) at metaphase of meiosis II, exhibiting the first polar body and with the ability to become fertilized. In an egg freezing cycle, only eggs considered mature will be kept and frozen. Because there is no test for egg quality, embryologists use this measure to determine which eggs are the most viable. 


Mild Ovarian Stimulation

A protocol in which the ovaries are stimulated with low doses of gonadotropins and/or other pharmacological compounds, with the intention of limiting the number of oocytes following stimulation for IVF or egg freezing. This approach is most commonly used in young patients and high responders, or in the really low responding patients that are not going to make that many eggs no matter the dose.


Miscarriage (also called ‘spontaneous abortion’)

A pregnancy ending in the spontaneous loss of the embryo or fetus before 20 weeks of gestation.



The condition in a cell resulting from the loss of a single chromosome yielding a single copy of that particular chromosome rather than the normal two. Also see “chromosomal abnormalities.”



The size and shape of sperm. Also used in the grading of embryos.



Sperm that are moving, “alive.”


Multiple-Infant Birth

A pregnancy that results in the birth of more than one infant. This is far less common now that more and more clinics are practicing single embryo transfer.


Non-donor 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.




The female reproductive cell, also called an egg.


Oocyte Preservation

See “Egg Freezing”



Ovaries are the primary female reproductive organs. These glands have three important functions: they secrete hormones, they protect the eggs a female is born with and they release eggs for possible fertilization.


Ovarian Hyperstimulation Syndrome (OHSS)

A potential complication of ovarian stimulation or ovulation induction whose symptoms can include  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. In modern-day fertility treatment, this condition and its more serious complications seldom occur, as better techniques have been developed both to prevent and treat these symptoms before they can become severe.


Ovarian Monitoring

The use of ultrasound and or blood tests to monitor follicle development and hormone production. During a stimulation cycle for egg freezing or IVF, it is typical to have five to six monitoring visits over a 10-12 day period. 


Ovarian Reserve

A term generally used to indicate the number of eggs remaining in the ovaries and reflecting the ability to reproduce multiple eggs during an ovarian stimulation cycle. Ovarian reserve can be assessed by any or a combination of several means, including female age; number of antral follicles on ultrasound (AFC); anti-Mullerian hormone levels (AMH); follicle stimulating hormone (FSH) and estradiol (estrogen) levels; response to gonadotropin stimulation.

Ovarian Stimulation

Also known as Controlled Ovarian Hyperstimulation. The use of medication to stimulate the ovaries with the aim of developing multiple follicles and eggs. This is used in ART procedures such as egg freezing and IVF.


Ovarian Tissue Cryopreservation

The process of slow-freezing or vitrification of tissue, with the intention of preserving reproductive capacity.  This procedure takes place with either the entire ovary or on strips of ovarian tissue that have been surgically excised from the ovary, and is most commonly used for cancer patients that cannot undergo the much more common stimulation and egg retrieval.


Ovarian Torsion

Rotation of the ovary on its own blood supply. Torsion is much more common when ovaries are enlarged, but this is a very rare adverse effect of ovarian stimulation. Surgery may be required to correct the torsion.



When the ovaries release a mature egg that is ready for fertilization.


Ovulatory Dysfunction

A diagnostic category used when a woman’s ovaries are not producing and ovulating 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 (PCOS) and anovulation due to low GnRH levels, called hypothalamic anovulation. With these conditions, it is not uncommon to see multiple immature ovarian cysts visible in an ultrasound test.



A mature egg or oocyte.


PCOS (Polycystic Ovary Syndrome)

A common hormonal condition in which an imbalance in the sex hormones may cause menstrual abnormalities, skin and hair changes, obesity, infertility and other long-term health problems. The name comes from the multiple small follicles, which line the ovaries of most women with the disorder. These women have irregular periods and do not ovulate on a regular basis contributing to infertility. The cause is usually multifactorial genetic so there is no cure, just medical treatments for infertility and other symptoms.


Pituitary Gland

A small organ at the base of the brain that secretes many hormones including prolactin, LH and FSH in response to signals (GnRH) from the hypothalamus. Some women need their pituitary suppressed before ovarian stimulation cycles, if their blood tests shows an elevated level of prolactin.


Preimplantation Genetic Testing (PGT) - previously called PGD or PGS

Techniques performed on embryos prior to freezing blastocyst stage embryos and prior to a subsequent embryo transfer. PGT-M is for detecting specific genetic conditions to reduce the risk of passing inherited diseases to children. PGT-A screens embryos for an abnormal number of chromosomes, and is the most common type of genetic testing of embryos for IVF. Patients who take advantage of this testing may increase their chance of pregnancy by eliminating the embryos which would likely result in a miscarriage. PGT-A is gaining in popularity, with some ART centers only transferring one chromosomally normal blastocyst per cycle.

Poor Ovarian Responder (POR) in assisted reproductive technology

see Diminished Ovarian Reserve.


Poor Ovarian Response (POR) to Ovarian Stimulation

A condition in which fewer than four follicles and/or oocytes are developed/obtained following ovarian stimulation with the intention of obtaining more follicles and oocytes.


Pregnancy (clinical definition)

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 (that is, a positive pregnancy test).


Premature Ovarian Aging

A condition in which a woman enters menopause before age 40 as a result of the ovaries ceasing ovulation and the production of estrogen. Also see ‘Diminished Ovarian Reserve’

Premature Ovarian Insufficiency

Previously known as premature ovarian failure. A condition when a woman's ovaries stop working normally before she is 40 years old. In 70-90% of cases the cause is unknown. Known causes include chemotherapy, genetic abnormalities, autoimmune issues, metabolic disorders, as well as diminished ovarian reserve.



A hormone produced by the ovary which prepares the uterus for implantation and supports the early pregnancy.



A non-profit organization with an established, nationwide network of chapters mandated to promote reproductive health and to ensure equal access to all family building options for men and women experiencing infertility or other reproductive disorders.


Semen Analysis

A standard test of a man's semen to check the number and shape of his sperm and their motility. The sperm counts, motility and morphology all provide important information about how the sperm will perform in natural conception or fertility treatment cycles.


A cryopreservation procedure in which the temperature of the cell(s) is lowered in a stepwise fashion, typically using a computer controlled rate, from physiological (or room) temperature to extreme low temperature. Slow-freezing is now considered an obsolete technique for freezing eggs or embryos


Social Egg Freezing

Egg freezing for non-medical reasons. Also known as “elective” or “planned” egg freezing.


Society for Assisted Reproductive Technology (SART)

An affiliate of ASRM composed of clinics and programs that provide quality ART.  Such clinics have to abide to very specific quality assurance and improvement parameters, advertising guidelines and accreditation agencies that regulate the embryology standards.  Patients should seek care from SART member clinics only for the highest quality patient care.  www.


Society for Reproductive Endocrinology (SREI)

Only fully board-certified reproductive endocrinologist doctors can be a member.



The use of high-frequency sound waves to create images of structures inside the body.  In ART, most sonograms (aka ultrasounds) are performed using a probe inserted into the vagina, which provides the best visualization of the uterus and ovaries.



The main agents of male reproduction, which are produced in the testes and released into the semen. Sperm are male gametes.


Spontaneous Abortion

See ‘Miscarriage.’



A permanent state of infertility.


Stimulated Cycle

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



In the context of reproductive medicine, stimulation refers to the use of hormonal medications to promote the ovaries to produce multiple mature eggs in a single cycle, as opposed to the single egg usually produced.



Not considered as severe as infertility, subfertility is often made in reference to a couple experiencing significant inefficiency in conceiving on their own, which is usually related to female age.


Stimulation of the ovaries, usually done with hormones, that causes them to produce multiple eggs instead of one. Another name commonly used for this is “controlled ovarian hyperstimulation.”


Thawed Embryo Cycle

See ‘Frozen Embryo Cycle.’



The process of raising the temperature of slow-frozen cell(s) from the storage temperature to room/physiological temperature. IVF lab staff (embryologists) refer to thawing of vitrified eggs as “warming.”


Transvaginal Ultrasound

A pelvic ultrasound conducted through the vagina to examine female reproductive organs (i.e. the growth of your follicles during the ovarian stimulation phase)



An abnormal number of chromosome copies in a cell, characterized by the presence of three homologous chromosomes rather than the normal two. The majority of human embryos with trisomies are incompatible with life. Down syndrome is due to trisomy for chromosome 21.


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.



A type of pelvic scanning technique used in ART to examine the female reproductive organs. In ART treatments it is specifically used for visualizing the follicles in the ovaries, (or in IVF, the gestational sac, or the fetus.) Often this is a transvaginal ultrasound (“transvaginal” means “through the vagina” so this is an internal examination). It could also be called an endovaginal ultrasound.


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.



The womb, the main female reproductive organ.



An ultra-rapid cryopreservation procedure using a “flash freezing” technique that prevents ice formation within a cell, whose aqueous phase is very quickly converted to a glass-like solid. Studies have demonstrated that vitrification is superior to any other method of egg freezing, including slow freezing.


Warming (cells)

The process of raising the temperature of a vitrified cell or cells from the storage temperature to room/physiological temperature. Also see “thawing.”



A fertilized egg before it begins to divide.


Glossary Sources:

Reproductive Medicine Associates of Connecticut and RESOLVE.

Zegers-Hochschild F, Adamson GD, Dyer S, et al. The International Glossary on Infertility and Fertility Care, 2017. Hum Reprod. 2017;32(9):1786-1801.

bottom of page