There are many scientific words and terms to learn in reproductive medicine, and you'll want to learn them all when you are trying to get pregnant. We'll help you make sense of it all!

Check out our complete list of pregnancy and fertility acronyms and abbreviations!

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 


Abortion, induced:

The intentional ending of a pregnancy.

Abortion, spontaneous:

Pregnancy loss by any cause before 20 weeks of gestation.


A membrane-bound structure covering the anterior of the sperm head.


A form of endometriosis marked by the presence of endometrium.


Bands of fibrous scar tissue that may bind the abdominal and pelvic organs (including the intestines and peritoneum) to each other. They can be dense and thick or filmy and thin.

Age-specific fertility rate (ASFR):

The number of live births per woman in a particular age group in a specific calendar year expressed per 1000 women in that age group.


Clumping of sperm in the ejaculate.


A condition in which a woman doesn't have menstrual periods.

American Society of Reproductive Medicine (ASRM):

Formerly the American Fertility Society (AFS), ASRM is a leading advocate for patient care, research, and education. This large multidisciplinary patient and physician organization serves as a platform for new ideas, education, and advocacy in fertility and reproductive medicine issues.


A procedure done in the second trimester of pregnancy that can detect many fetal abnormalities. It is performed by sampling a small quantity of the amniotic fluid that surrounds the fetus with a needle under ultrasound guidance.


The medical practice dealing with the health of the male reproductive system.


An abnormal number of chromosomes in a cell. The majority of embryos with aneuploidies are not compatible with life.


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

Antisperm antibodies:

Antibodies that recognize and bind to antigens on the surface of the sperm.

Antisperm antibody test:

A test that can determine if antibodies on the surface of sperm are interfering with the ability of sperm to move, penetrate the cervical mucus, or fertilize an egg.

Artificial insemination:

The general name for the procedure in which sperm are inserted directly into a woman's cervix, fallopian tubes, or uterus.


Lack of sperm, absence of sperm in the semen.


Removal of fluid and cells by suction through a needle. This technique applies to many procedures in reproductive medicine.

Assisted hatching (AH):

An ART procedure in which the zona pellucida of an embryo is either thinned or perforated by chemical, mechanical or laser methods in the lab prior to embryo transfer in IVF cycles.

Assisted reproduction technology (ART):

The general term for infertility procedures involving both an egg and sperm. This group of fertility therapies employ manipulations of the egg and sperm in the lab in order to establish a pregnancy.


Reduced percentages of motile and morphologically normal sperm in the semen.


The absence of motile and viable sperm in the semen.



Basal body temperature (BBT):

The body temperature at rest taken in the morning before arising from bed. Successive BBT’s can be measured orally each morning and recorded on a calendar chart to help identify ovulation. 

beta HCG:

See Human Chorionic Gonadotropin (hCG).


The presence of two nuclei in a cell.

Biochemical pregnancy:

A pregnancy diagnosed only by the detection of beta hCG in serum or urine.


The complete expulsion or extraction of a fetus after 22 completed weeks of gestational age, irrespective of whether it is a live birth or stillbirth.


Fluid-filled central region of the blastocyst.


The stage of preimplantation embryo development that occurs around day 5–6 after insemination. The blastocyst contains a fluid-filled central cavity, an outer layer of cells, and an inner group of cells.

Blastomere symmetry:

The extent to which all blastomeres are even in size and shape.


A cell in a cleavage stage embryo.

Bleeding after oocyte aspiration:

Significant bleeding, internal or external, after oocyte aspiration retrieval requiring hospitalization for blood transfusion, surgical intervention, clinical observation or other medical procedures.



Canceled ART cycle:

An ART cycle in which ovarian stimulation has been initiated with the intention to treat, but which did not proceed to follicular aspiration or in the case of a thawed or warmed embryo, did not proceed to embryo transfer.


The process that sperm must undergo in order to fertilize an egg.

Cervical factor:

Infertility due to a structural or hormonal abnormality of the cervix. This can be induced by previous surgery on the cervix that leaves the cervical canal scarred or closed. Also applied when there are factors with the cervix which inhibit sperm function such as thickened mucus.

Cervical mucus:

Normal secretions of the cervix which change in volume and consistency throughout the menstrual cycle. Cervical mucus quality is a reflection of hormonal stimulation.


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.

Cesarean section:

The abdominal delivery of a baby, after an incision is made through the abdomen and the uterus.

Chemical pregnancy:

A positive pregnancy test, but with levels of pregnancy hormone (beta hCG) too low for ultrasound documentation of a pregnancy. Typically these pregnancies have low beta hCG levels that spontaneously decline without any further development.


Presence in a single individual of two or more cell lines, each derived from different individuals.

Cleavage stage embryos:

Embryos beginning with the 2 cell stage and up to, but not including, the morula stage.


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

Clinical fertility:

The capacity to establish a clinical pregnancy.

Clinical pregnancy:

A pregnancy that has been confirmed by a positive pregnancy test, a sonogram, or a beating fetal heart by ultrasound.


A fertility drug given to women to stimulate ovulation.

Clomiphene citrate:

Also known as Clomid TM or Serophene TM, an oral medication used to stimulate the ovaries and/or synchronize follicle development.

Cohort total fertility rate (CTFR):

The observed average number of live-born children per woman applied to a birth cohort of women as they age through time. This is obtained from data on women after completing their reproductive years.


The process during which tight junctions form between juxtaposed blastomeres resulting in a solid mass of cells with indistinguishable cell membranes.

Complex aneuploidies:

Two or more aneuploidies involving different chromosomes in the embryo. When autosomes are involved, this condition is not compatible with human life.


AKA fertilization, conception is the time when you get pregnant. It usually occurs at the same time as ovulation, about 12-16 days before the next period. 

Congenital anomaly:

A nonhereditary characteristic, or defect, developed before birth. Can be caused by single gene defects, chromosomal disorders, multifactorial inheritance, environmental teratogens, and micronutrient deficiencies. 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. 

Congenital anomaly birth rate:

The number of births exhibiting signs of congenital anomalies per 10,000 births. 

Congenital bilateral absence of the vasa deferentia:

The absence at birth, of both duct systems (vas deferentia) that connect the testes to the urethra and may be associated with cystic fibrosis transmembrane conductance regulator gene mutation. Although the testes usually develop and function normally, men present with azoospermia.

Conventional in vitro insemination:

The co-incubation of eggs with sperm in-vitro with the goal of resulting in extracorporeal fertilization.

Corona radiata cells:

The innermost cells of the cumulus oophorus.

Corpus luteum:

A special gland that forms from the ovulated follicle in the ovary. It produces progesterone during the second half of the menstrual cycle which is necessary to prepare the uterine lining for implantation. It also supports early pregnancies by secreting the necessary hormones until the placenta becomes fully functional between 8 10 weeks of gestation.

Cross border reproductive care:

The provision of reproductive health services in a different jurisdiction or outside of a recognized national border within which the person or persons legally reside.

Cryptic ("Stealth") Pregnancy

A cryptic or stealth pregnancy, is an actual pregnancy that is  not accepted or recognized by the pregnant woman.  Another definition is that a cryptic pregnancy is a pregnancy missed by conventional medical testing methods, though for example doing a sonogram nearly always properly identifies the pregnancy after 6-8 weeks.


The process of slow freezing or vitrification to preserve biological material (e.g. gametes, zygotes, cleavage stage embryos, blastocysts or gonadal tissue) at extremely low temperatures.
This may be employed for sperm, embryos, and eggs.


Testis not in scrotal position within the neonatal period and, up to but not limited to, 1-year post-birth. If the testis has not descended into the scrotum, this condition can cause primary testicular failure and increased risk of testicular cancer development.

Cumulative delivery rate per aspiration/initiated cycle with at least one live birth:

The number of deliveries with at least one live birth resulting from one initiated or aspirated ART cycle, including all cycles in which fresh and/or frozen embryos are transferred, until one delivery with a live birth occurs or until all embryos are used, whichever occurs first.

Cumulus oophorus:

The multi-layered mass of granulosa cells surrounding the egg.


The cloud-like collection of supportive follicle cells that surround the egg.


A fluid-filled structure. Cysts may be found anywhere in the body, but in reproductive medicine, it primarily refers to cysts in the ovaries. Ovarian cysts may be normal or abnormal. 

Cytoplasmic maturation:

The process during which the egg acquires the capacity to support nuclear maturation, fertilization, pronuclei formation, syngamy and subsequent early cleavage divisions until activation of the embryonic genome.

Cytoplasmic transfer:

A procedure that can be performed at different stages of an egg's development to add to or replace various amounts of cytoplasm from a donor egg.



Decreased spermatogenesis:

A decreased number or absence of sperm in the semen.

Delayed ejaculation:

A condition in which it takes a man an extended period of time to reach orgasm and ejaculation.

Delayed embryo transfer:

A procedure in which embryo transfer is not performed within the time frame of the egg aspiration cycle but at a later time.

Delivery rate after fertility treatment per patient:

The number of deliveries with at least one live birth or stillbirth, expressed per 100 patients.

Delivery rate:

The number of deliveries expressed per 100 initiated cycles, aspiration cycles, or embryo transfer cycles. 


The complete expulsion or extraction of a fetus after 22 completed weeks of gestational age, irrespective of whether it is a live birth or stillbirth.

Delivery with multiple births after fertility treatment:

Giving birth to more than one newborn following fertility treatment.

Diandric oocytes:

An egg with an extra set of haploid chromosomes of paternal origin.

Digynic oocytes:

An egg with an extra set of haploid chromosomes of maternal origin.

Diminished ovarian reserve:

A term generally used to indicate a reduced number and/or reduced quality of eggs, such that the ability to reproduce is decreased.


The condition in which a cell has two haploid sets of chromosomes. Each chromosome in one set is paired with its counterpart in the other set. A diploid embryo has 22 pairs of autosomes and two sex chromosomes.


The normal number of chromosomes characterized by 22 pairs of autosomal chromosomes and one pair of sex chromosomes (XX or XY). The chromosome number in human cells is normally 46.

Donor egg cycle:

The use of donated eggs from an anonymous or known donor. These eggs are harvested via an IVF cycle performed on the donor. The resultant eggs are inseminated with sperm and then form embryos that are transferred into the womb of the intended parent.

Donor eggs:

Eggs that are taken from a fertile woman and implanted in another woman.

Donor embryo transfer:

The transfer of embryos resulting from the egg and sperm of another patient, who may be anonymous or known, to an otherwise infertile recipient.

Donor insemination:

The process of placing laboratory-processed sperm or from a man into the reproductive tract of a woman who is not his intimate sexual partner in order to achieve a pregnancy.

Double embryo transfer (DET):

The transfer of two embryos in an ART procedure. This may be elective when more than two embryos of sufficient quality for transfer are available.

Ductus deferens (vas):

A thick-walled tubular structure running from each testis into the ejaculatory duct. These structures carry sperm from the testicles to the epididymis to the penis for ejaculation. 



Early neonatal death/mortality:

Death of a newborn within 7 days of birth.

Ectopic pregnancy:

A pregnancy implanted outside the uterus; most often in the fallopian tube. This is also termed a tubal pregnancy. Left undiagnosed and untreated, an ectopic pregnancy can have serious medical consequences. 

Egg aka ovum: 

A mature female reproductive cell. When fertilized by a male cell, it can divide and grow into an embyro.

Egg retrieval:

The procedure during an IVF cycle where the eggs are harvested through a minimally invasive surgical procedure. This is done under light anesthesia and typically takes about 30 minutes.


Coordinated contractions of the male genitourinary tract leading to the ejection of sperm 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 combine.

Elective embryo transfer:

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

Elective single embryo transfer:

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

Embryo bank:

Repository of cryopreserved embryos stored for future use.

Embryo donation:

An ART cycle which consists of the transfer of an embryo to the uterus or fallopian tube of a female recipient that did not originate from the female recipient or from her male partner.

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 that did not originate from her or from her male partner.


The term used to describe the early stages of fetal growth. Strictly defined from the second to the ninth week of pregnancy but often used to designate any time after conception.

Embryo transfer:

The procedure of transferring embryos back into the endometrial cavity (womb) of a patient during an IVF cycle. It occurs on the third or fifth day after egg retrieval.

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):

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


The study of hormones, their function, the organs that produce them and how they are produced.

Endometrial biopsy:

The extraction of a small piece of tissue from the endometrium (lining of the uterus) for microscopic examination.

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. Commonly referred to as the womb.


A painful condition in which tissue from the lining of the uterus (the endometrium) grows outside of the uterus. The presence of endometrial tissue (tissue that normally lines the uterus) in abnormal locations such as the ovaries, fallopian tubes, and abdominal cavity. 


The inner lining of the uterus that responds to female hormones during the menstrual cycle and treatment cycles. This lining, when properly prepared, forms the area of attachment and implantation of the embryo.


A convoluted, highly coiled duct that transports the sperm from the testis via the efferent ducts to the vas deferens. Portion of the male genital tract next to the testis where sperm maturation is partially accomplished. 

Erectile dysfunction:

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


A strategy to decrease your chances of having even twins if your physician transfers only a single embryo into your womb during IVF, the chances of having twins are reduced to almost zero. The trade-off is a lower pregnancy rate; the fewer embryos you put in, the fewer chances you have of one implanting.


The principal hormone produced by the growing ovarian follicle. It is frequently measured in the blood to gauge the strength and development of your follicles during treatment cycles.


The condition in which a cell has chromosomes in an exact multiple of the haploid number. In humans, 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.



Fallopian tube:

Two hollow tubes on either side of the uterus where the egg and sperm meet to begin the process of fertilization.


The probability of pregnancy during a single menstrual cycle in a woman with adequate exposure to sperm and no contraception, culminating in a live birth. 


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.

Fertile window:

The 5-6 fertile days of your menstrual cycle; 4-5 days before and the day of ovulation when intercourse is most likely to result in pregnancy.

Fertility awareness:

Part of Natural Family Planning; uses a woman's natural fertility signs to identify when she may or may not be fertile.

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.

Fertility preservation:

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


The capacity to establish a clinical pregnancy.


Union of a sperm with an egg to facilitate the creation of a genetically unique embryo.

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.

Fetal reduction:

An intervention intended to reduce the number of gestational sacs or embryos/fetuses in a multiple gestation.


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.


Overgrowth of the muscular tissue of the uterus. Fibroids are typically knotty masses of benign muscle tissue that can distort the shape and function of the uterus. 


The soft and supple finger-like extensions of the fallopian tube that aid in gathering in the egg at ovulation.

Follicle-stimulating hormone (FSH):

A hormone produced by the pituitary gland in the brain that stimulates the ovarian follicles to grow and develop. FSH is measured in the blood at specialized times during the menstrual cycle to help measure ovarian reserve. 


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 (and the medications that mimic these hormones). 

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 onset of menses to ovulation, and lasts approximately 14 days. It is associated with developing follicles that produce estradiol.

Freeze all cycle:

An ART cycle in which, after egg aspiration, all eggs and/or embryos are cryopreserved and no eggs 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 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 tube transfer (GIFT):

An older method of assisted fertilization that involves surgically removing an egg from the ovary, combining it with sperm, and immediately surgically placing the egg and sperm into the fallopian tube. Fertilization takes place inside the fallopian tube. 

Germinal vesicle (GV):

The nucleus in an egg 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. 

Gestational carrier:

A woman who carries a pregnancy with an agreement that she will give the offspring to the intended parent(s). 

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 sperm with a reduced or absent acrosome.


Hormones that stimulate the ovary.

Gonadotropin-releasing hormone (Gn RH):

A hormone produced by the hypothalamus in the brain that stimulates the pituitary gland to secrete gonadotropins.

Gonadotropin-releasing hormone agonists and antagonists (GnRH Agonist):

Synthetic hormones that perform the same function as natural Gn RH.



Hamster test:

See Sperm Penetration Assay.


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 its shell, 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.

Human chorionic gonadotropin (hCG):

A hormone of early pregnancy that is monitored to determine the viability of the gestation. This hormone is also used as an injection to induce ovulation and maturation of the egg in ovarian stimulation protocols.

Human menopausal gonadotropin (HMG):

A hormone used by injection to facilitate the development of multiple follicles in treatment cycles.


See human menopausal gonadotropin.


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. 

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 sperm in the testes.


Low volume of ejaculate below the lower reference limit. 


A portion of the brain that stimulates the pituitary gland to secrete LH and FSH in order to stimulate ovarian follicle development.

Hysterosalpingogram (HSG):

An x-ray procedure to examine whether the fallopian tubes are patent (open) or not. This test helps determine if the tubes are blocking sperm from reaching the ovulated eggs through the fallopian tubes. 

Hysteroscope/hysteroscopic surgery:

Minimally invasive surgery in which a small telescopic camera, much like a laparoscope, is placed through the cervical canal into the uterine cavity. This allows direct visualization of the endometrium, the lining of the uterine cavity (the womb) where pregnancy implants. 

Hysteroscopic sterilization:

A form of permanent sterilization in which a small device is planted in each fallopian tube. The device called Essure irritates the tubes, causing scarring which closes them off. 


A procedure in which a thin, telescope-like instrument is inserted through the cervix into the uterus, allowing the doctor to see and photograph the area, and correct problems if needed.



Iatrogenic testicular failure:

Damage to testicular function after radiation, chemotherapy or hormone treatment; or devascularization as a consequence of hernia surgery.

Immature oocyte:

An egg at the germinal vesicle stage.

Implantation rate:

The number of gestational sacs observed divided by the number of embryos transferred (usually expressed as a percentage).


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

In-vitro fertilization (IVF):

An assisted reproductive technique that involves removing sperm and eggs, fertilizing them in a laboratory, then placing a fertilized egg in the uterus.

In-vitro maturation (IVM):

A sequence of laboratory procedures that enable extracorporeal maturation of immature eggs into fully mature eggs that are capable of being fertilized with the potential to develop into embryos.

Induced abortion:

The intentional ending of a pregnancy.


The failure to establish a clinical pregnancy after 12 months of regular, unprotected sexual intercourse or due to an impairment of a person's capacity to reproduce either as an individual or with his/her partner. 

Infertility counseling:

Professional therapy sessions to address the physical, emotional and psychosocial consequences of infertility.

Initiated medically assisted reproduction cycle (iMAR):

A cycle in which the woman receives specific medication for ovarian stimulation or in which cycle monitoring is carried out with the intention to treat, irrespective of whether or not insemination is performed.

Inner cell mass:

A group of cells attached to the polar trophectoderm consisting of embryonic stem cells, which have the potential to develop into cells and tissues in the human body, except the placenta or amniotic membranes.


Transfer of sperm for the purpose of establishing a pregnancy. Inseminations are performed by placing a small, soft catheter through the cervix into the uterine cavity and depositing the concentrated and activated sperm.

Intended parent(s):

A couple or person who seek(s) to reproduce with the assistance of a gestational carrier or traditional gestational carrier.

Intra cervical insemination:

A procedure in which laboratory-processed sperm are placed in the cervix to attempt a pregnancy.

Intra-uterine insemination (IUI):

A procedure in which laboratory-processed sperm are placed in the uterus to attempt a pregnancy.

Intrauterine pregnancy:

A state of reproduction in which an embryo has implanted in the uterus.

Intracytoplasmic sperm injection (ICSI):

A laboratory procedure in which sperm and eggs are retrieved from both partners, and a single sperm is injected directly into an egg, then the fertilized egg is implanted into the woman's uterus. 

Intrauterine insemination (IUI):

An artificial insemination technique in which sperm are put directly into a woman's uterus at the time she is ovulating.



it is the yellow color seen in the skin of newborns. Jaundice happens when a chemical called Bilirubin builds up in the baby’s blood. If not treated, high levels of Bilirubin can cause brain damage.


Kegels exercises are designed to strengthen and give voluntary control over the pubococcygeus muscles (muscles that surround the vagina and help with urinary control and childbirth) .



Laparoscopic surgery:

Minimally invasive surgery using a thin, lighted viewing instrument with a telescopic lens through which a surgeon views the exterior surfaces of female reproductive organs and abdominal cavity. 

Laparoscopic ovarian drilling:

A surgical method for inducing ovulation in females with anovulatory or oligo ovulatory polycystic ovarian syndrome, utilizing either laser or electrosurgery.


A procedure that involves the insertion of a narrow, telescope-like instrument called a laparoscope through a small incision in the abdomen.

Large for gestational age:

Birth weight greater than the 90th centile of the sex-specific birth weight for a given gestational age reference. 


A high number of white blood cells in semen above the upper reference limit. 

Leydig cell:

Type of testicular cell located in the interstitial space between the seminiferous tubules, that secretes testosterone.

Listeria or Listeriosis

Listeria is a type of bacteria carried in some foods and can lead to food posioning that can lead to infection of a person and complications such as miscarriage, premature labor, stillbirth, or it can infect a newborn baby. Pregnant women can reduce their risk of listeria by eating wisely.

Live birth delivery rate:

The number of deliveries that resulted in at least one live birth, expressed per 100 cycle attempts. 

Live birth:

The complete expulsion or extraction of a fetus after 22 completed weeks of gestational age, irrespective of whether it is a live birth or stillbirth.

Low birth weight:

Birth weight less than 2500 g.


A synthetic form of GnRH (a gonadotropin-releasing hormone secreted by the hypothalamus) used to suppress ovarian function.

Luteal phase:

The menstrual cycle is divided up into two main parts the follicular phase and the luteal phase. This refers to the second half of the cycle, usually the last fourteen days. It begins from the time of ovulation to the onset of menses but is prolonged during pregnancy cycles. 

Luteal phase defect:

A poorly defined abnormality of the endometrium presumably due to abnormally low progesterone secretion.

Luteal phase deficiency (LPD):

Also called luteal phase defect. A deficiency of progesterone in the second half of the menstrual cycle when pregnancy begins. 

Luteal phase support:

Hormonal supplementation in the luteal phase, usually progesterone.

Luteinizing hormone (LH):

A hormone produced and released by the pituitary gland. In the female, it is responsible for ovulation and the maintenance of the corpus luteum. In the male, it stimulates testosterone production and is important in the production of sperm cells. 



Major congenital anomaly:

A congenital anomaly that is a visually evident or life-threatening structural or functional defect, requires surgical repair or causes death.

Male infertility:

Infertility caused primarily by male factors encompassing abnormal semen parameters or function; anatomical, endocrine, genetic, functional or immunological abnormalities of the reproductive system; chronic illness; and sexual conditions incompatible with the ability to deposit semen in the vagina.

Maternal spindle transfer:

Transfer of the maternal spindle (including maternal chromosomes) from a patient's egg into a donated egg in which the maternal spindle with chromosomes has been removed.

Mature oocyte:

An egg at metaphase of meiosis II with the ability to become fertilized.


Fluid containing nutritive growth substances enabling cells to survive in an artificial environment.

Medically assisted reproduction (MAR):

Reproduction brought about through various interventions, procedures, surgeries, and technologies to treat different forms of fertility impairment and infertility. 


When menstruation first occurs, the first menstrual cycle.


When the menstrual cycle ends and a woman stops getting her period. Menopause occurs when a woman has not had a period for one full year.


A menstrual period.


Human FSH prepared in an injectable form for ovarian stimulation.

Microdissection testicular sperm extraction (MicroTESE):

A surgical procedure using an operating microscope to identify seminiferous tubules that may contain sperm to be extracted for IVF and/or ICSI.

Micromanipulation in ART:

A micro operative ART procedure performed on sperm, egg or embryo; the most common ART micromanipulation procedures are ICSI, assisted hatching and gamete or embryo biopsy for PGT.


The name of a group of laboratory techniques that allow sperm, eggs, and embryos to be performed under the guidance of the microscope.

Microsurgical epididymal sperm aspiration/extraction:

A surgical procedure performed with the assistance of an operating microscope to retrieve sperm from the epididymis of men with obstructive azoospermia.

Mild ovarian stimulation for IVF:

A protocol in which the ovaries are stimulated with gonadotropins, and/or other pharmacological compounds, with the intention of limiting the number of oocytes following stimulation for IVF.


A miscarriage (or spontaneous abortion) is a pregnancy that ends without intervention, surgery or medication, before the 20th week of pregnancy.

Missed abortion:

Spontaneous loss of a clinical pregnancy before 22 completed weeks of gestational age, in which the embryo(s) or fetus(es) is/are nonviable and is/are not spontaneously absorbed or expelled from the uterus.

Modified natural cycle:

An ART procedure in which one or more eggs are collected from the ovaries during a spontaneous menstrual cycle.


The absence of one of the two homologous chromosomes in embryos. Autosomal monosomies in embryos are not compatible with life.


The size and shape of sperm.


An embryo formed after completion of compaction, typically 4 days after insemination or ICSI.


A state in which there is more than one karyotypically distinct cell population arising from a single embryo.


The ability of sperm to move by themselves.


The presence of more than one nucleus in a cell.

Multiple birth:

The complete expulsion or extraction from a woman of more than one fetus, after 22 completed weeks of gestational age, irrespective of whether it is a live birth or stillbirth. 

Multiple gestation:

A pregnancy with more than one embryo or fetus.



Natural cycle ART:

An ART procedure in which one or more eggs are collected from the ovaries during a menstrual cycle without the use of any pharmacological compound.


The description of an ejaculate in which no live sperm can be found.

Neonatal death/mortality:

Death of a live-born baby within 28 days of birth. This can be subdivided into a) early, if death occurs in the first 7 days after birth; and b) late, if death occurs between 8 and 28 days after birth.

Neonatal mortality rate:

Number of neonatal deaths (up to 28 days) per 1000 live births.

Neonatal period:

The period which commences at birth and ends at 28 completed days after birth.

Non-obstructive azoospermia:

Absence of spermatozoa in the ejaculate due to lack of production of mature spermatozoa.

Nuclear maturation:

The process during which the egg resumes meiosis and progresses from prophase I to metaphase II.



Obstructive azoospermia:

Absence of spermatozoa in the ejaculate due to occlusion of the ductal system.


A condition that causes infrequent menstrual periods.


When a man has too few sperm to fertilize an egg normally. Low concentration of sperm in the ejaculate below the lower reference limit. 

Oocyte aspiration:

Ovarian follicular aspiration performed with the aim of retrieving eggs.

Oocyte bank:

Repository of cryopreserved eggs stored for future use.

Oocyte cryopreservation:

The freezing or vitrification of eggs for future use.

Oocyte donation cycle:

An ART cycle in which oocytes are collected from an egg donor for reproductive purposes or research.

Oocyte donation:

The use of oocytes from an egg donor for reproductive purposes or research.

Oocyte maturation triggering:

An intervention intended to induce an egg in vitro or in vivo to resume meiosis to reach maturity.

Oocyte recipient cycle:

An ART cycle in which a woman receives eggs from a donor, or her partner if in a same sex relationship, to be used for reproductive purposes.


The female gamete (egg). The female germ cell often called an egg.


The cytoplasmic membrane enclosing the oocyte.


The cytoplasm of the oocyte.

Ovarian hyperstimulation syndrome (OHSS):

An exaggerated systemic response to ovarian stimulation characterized by a wide spectrum of clinical and laboratory manifestations. It may be classified as mild, moderate or severe according to the degree of abdominal distention, ovarian enlargement, and respiratory, hemodynamic and metabolic complications.

Ovarian reserve:

A term generally used to indicate the number and/or quality of eggs, reflecting the ability to reproduce. Ovarian reserve can be assessed by any of several means, including female age; the number of antral follicles on ultrasound; anti-Mullerian hormone levels; follicle-stimulating hormone and estradiol levels; clomiphene citrate challenge test; response to gonadotropin stimulation, and oocyte/embryo assessment during an ART procedure.

Ovarian stimulation (OS):

Pharmacological treatment with the intention of inducing the development of ovarian follicles. It can be used for two purposes 1) for timed intercourse or insemination; 2) in ART, to obtain multiple oocytes at follicular aspiration.

Ovarian tissue cryopreservation:

The process of slow freezing or vitrification of tissue surgically excised from the ovary with the intention of preserving reproductive capacity.

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.


The female sex gland with both a reproductive function (releasing eggs) and a hormonal function (production of estrogen and progesterone).


The release of a mature egg from the surface of the ovary. When the ovaries release a mature egg that is ready for fertilization.

Ovulation induction (OI):

Pharmacological treatment of women with anovulation or oligo ovulation with the intention of inducing normal ovulatory cycles. 

Ovum (ova or egg):

Mature oocytes, an egg.



Pap smear test:

A screening test to determine the presence of cervical cancer. It is done by gently touching a swab to the cervix to collect cells for examination by a pathologist.

Parthenogenetic activation:

The process by which an egg is activated to undergo development in the absence of fertilization.


The product of an egg that has undergone activation in the absence of the paternal genome, with (induced) or without (spontaneous) a purposeful intervention.

Pelvic inflammatory disease (PID):

Inflammation of the uterus, fallopian tubes, and ovaries due to infection; a cause of infertility in some women.

Percutaneous epididymal sperm aspiration (PESA):

A surgical procedure in which a needle is introduced percutaneously into the epididymis with the intention of obtaining sperm.


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

Perinatal death/mortality:

Fetal or neonatal death occurring during late pregnancy (at 22 completed weeks of gestational age and later), during childbirth, or up to seven completed days after birth.

Period total fertility rate (PTFR):

The estimated average number of live-born children per woman that would be born to a cohort of women throughout their reproductive years, if the fertility rates by age in a given period remained constant at the current age-specific fertility rate.

Perivitelline space:

The space between the cytoplasmic membrane enclosing the egg and the innermost layer of the zona pellucida. 

Pituitary down-regulation:

A medical or pharmacological method to prevent the release of gonadotropins (FSH, LH) from the pituitary gland.

Pituitary gland:

A small organ at the base of the brain that secretes many hormones, including LH and FSH in response to signals from the hypothalamus.

Polar bodies:

The small bodies containing chromosomes segregated from the egg by asymmetric division during telophase. 

Polycystic ovarian syndrome (PCOS):

A common endocrinologic condition that causes hormonal imbalances in women of reproductive age. It can lead to dysfunctional ovulation, infertility, weight gain, pre-diabetes and an increase in the male hormone, testosterone. 

Polycystic ovary:

An ovary with at least 12 follicles measuring 2–9 mm in diameter in at least one ovary (Rotterdam criteria). PCO may be present in women with PCOS, but also in women with normal ovulatory function and normal fertility.


An overgrowth of the glandular surface of the endometrium. Polyps are often removed by hysteroscopic surgery to remove any impediments to implantation.


The condition in which a cell has more than two haploid sets of chromosomes e.g. a triploid embryo has three sets of chromosomes and a tetraploid embryo has four sets. Polyploidy in a human embryo is not compatible with life.


Abnormal condition where the egg is fertilized by more than 1 sperm.

Poor ovarian responder (POR) in ART:

A woman treated with ovarian stimulation for ART, in which at least two of the following features are present (1) advanced maternal age (≥40 years); (2) a previous poor ovarian response; (3) an abnormal ovarian reserve test.

Poor ovarian response (POR):

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

Post-coital test (PCT):

A standard fertility test in which a sample of cervical mucus is taken after intercourse to check the number and behavior of the sperm. 

Post implantation embryo:

An embryo at a stage of development beyond attachment to the endometrium to eight completed weeks after fertilization, which is equivalent to 10 weeks of gestational age.

Post-term birth:

A live birth or stillbirth that takes place after 42 completed weeks of gestational age.

Posthumous reproduction:

A process utilizing gametes and/or embryos from a deceased person or persons with the intention of producing offspring.


A dangerous pregnancy complication that causes high blood pressure, swelling, water retention, and a high level of protein in the urine.

Preimplantation embryo:

An embryo at a stage of development beginning with the division of the zygote into two cells and ending just prior to implantation into a uterus.


A state of reproduction beginning with implantation of an embryo in a woman and ending with the complete expulsion and/or extraction of all products of implantation.

Pregnancy loss:

The outcome of any pregnancy that does not result in at least one live birth. When reporting pregnancy loss, the estimated gestational age at the end of pregnancy should be recorded.

Pregnancy of unknown location (PUL):

A pregnancy documented by a positive human chorionic gonadotropin (hCG) test without visualization of pregnancy by ultrasound. This condition exists only after circulating hCG concentration is compatible with ultrasound visualization of a gestational sac.

Preimplantation genetic diagnosis (PGD) and screening (PGS):

These terms have now been replaced by preimplantation genetic testing (PGT). 

Preimplantation genetic diagnosis (PGD):

A technique for identifying genetic or chromosomal information about embryos before transferring them back to a patient’s endometrial cavity (the womb). It helps identify embryos that carry a genetic disease that may be asymptomatically carried by the parents, or it may be used to identify explanations for Recurrent pregnancy loss.

Preimplantation genetic testing (PGT):

A test performed to analyze the DNA from eggs or embryos for HLA typing or for determining genetic abnormalities. These include PGT for aneuploidies (PGT A); PGT for monogenic/single gene defects (PGT M); and PGT for chromosomal structural rearrangements (PGT SR).

Premature ejaculation:

A condition in which semen is released sooner than desired.

Premature ovarian failure:

A condition in which a woman enters menopause before age 40 as a result of the ovaries ceasing ovulation and the production of estrogen.

Premature ovarian insufficiency:

A condition characterized by hypergonadotropic hypogonadism in women younger than age 40 years (also known as premature or primary ovarian failure). It includes women with premature menopause.

Preterm birth:

A birth that takes place after 22 weeks and before 37 completed weeks of gestational age.

Primary childlessness:

A condition in which a person has never delivered a live child, or has never been a legal or societally recognized parent to a child.

Primary female infertility:

A woman who has never been diagnosed with a clinical pregnancy and meets the criteria of being classified as having infertility.

Primary involuntary childlessness:

A condition in a person who has never delivered a live child, or has never been a legal or societally recognized parent to a child. A major cause of primary involuntary childlessness is infertility.

Primary male infertility:

A man who has never initiated a clinical pregnancy and meets the criteria of being classified as infertile.


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

Pronuclear stage tubal transfer (PROST or ZIFT):

An older procedure in which eggs are harvested and inseminated in the laboratory before surgically transferring these very early zygotes into the fallopian tubes. This procedure has been replaced by standard IVF.

Pronuclei transfer:

Transfer of the pronuclei from a patient's zygote to an enucleated donated zygote.


A specialized stage of the egg and sperm nucleus before they join to create a genetically unique embryo. After this union the conceptus is referred to as a zygote.



Recipient (ART):

A person or couple who receives donated eggs, sperm or embryos for the purposes of initiating a pregnancy with the intention of becoming a legally recognized parent.

Recipient ART cycle:

An ART cycle in which a woman receives zygote(s) or embryo(s) from donor(s) or a partner.

Recurrent spontaneous abortion/miscarriage:

The spontaneous loss of two or more clinical pregnancies prior to 22 completed weeks of gestational age.

Reproductive surgery:

Surgical procedures performed to diagnose, conserve, correct and/or improve reproductive function in either men or women. 


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. 

Retrograde ejaculation:

A condition in which semen enters the bladder during ejaculation instead of leaving the penis.

Round spermatid nucleus injection (ROSNI):

An experimental fertilization technique in which immature sperm cells are removed from the testicle and the genetic material is injected into an egg.




The surgical removal of an entire fallopian tube.

Salpingitis isthmica nodosa (SIN):

Nodular thickening of the proximal fallopian tube which can distort the tubes and increase the risk of ectopic pregnancy and infertility.


A surgical procedure in which an opening is made in the fallopian tube either to remove an ectopic pregnancy or open a blocked fluid-filled tube.

Secondary female infertility:

When a woman is unable to establish a clinical pregnancy but has previously been diagnosed with a clinical pregnancy.

Secondary involuntary childlessness:

A condition in a person who has previously delivered a live child, or is or has been a legal or societally recognized parent to a child. A major cause of secondary involuntary childlessness is infertility.

Secondary male infertility:

A man who is unable to initiate a clinical pregnancy, but who had previously initiated a clinical pregnancy.

Semen analysis:

A standard test of a man's semen to check the number and shape of his sperm and their motility. Examination of the male ejaculate under the microscope to determine the number of sperm, their ability to move forward (motility) and their shapes (morphology). The semen analysis is a cornerstone of the evaluation of couples experiencing infertility. 

Semen liquefaction:

The process whereby proteolytic enzymes degrade proteins causing the seminal plasma to liquefy.

Semen viscosity:

The description of the relative fluidity of seminal plasma.

Semen volume:

The amount of fluid in an ejaculate.


The fluid at ejaculation that contains the cells and secretions originating from the testes and sex accessory glands.

Seminal plasma:

The fluids of the ejaculate.

Sertoli cell:

The non germinal cell type in the seminiferous tubule that mediates the actions of testosterone and FSH in the testis, provides nutrients and proteins to the developing spermatogenic cells, creates the blood testis barrier, and secretes Mullerian inhibiting hormone.

Sertoli cell-only syndrome:

A condition in which only Sertoli cells line the seminiferous tubules with usually a complete absence of germ cells; also referred to as germ cell aplasia.

Severe ovarian hyperstimulation syndrome (OHSS):

A systemic response as a result of ovarian stimulation interventions that is characterized by severe abdominal discomfort and/or other serious biochemical abnormalities requiring hospitalization.

Single embryo transfer (SET) or elective single embryos transfer (eSET):

A specific definition of only transferring a single embryo at the culmination of an IVF cycle. Defined as elective (eSET) when more than one embryo of sufficient quality for transfer is available.

Slow freezing:

A cryopreservation procedure in which the temperature of the cell(s) is lowered in a stepwise fashion, typically using a computer-controlled rate, from room temperature to extreme low temperature.

Small for gestational age:

A birth weight less than the 10th centile for gestational age. 

Society for Assisted Reproductive Technology (SART):

Regulatory and consultative organization of the American Society for Reproductive Medicine responsible for assisted reproduction. This organization works with the CDC to publicly post fertility rates of all IVF centers in the U.S.


The use of high-frequency sound waves to create images of structures inside the body.

Sperm bank:

Repository of cryopreserved sperm stored for future use.

Sperm concentration:

The measure of the number of spermatozoa in millions per 1 ml of semen.

Sperm density:

A measure of the mass/volume ratio for spermatozoa.

Sperm isolation:

A procedure that involves the separation of sperm through centrifugation and resuspension in culture media. It can be used to remove seminal plasma and infectious agents before IUI and ART procedures. This procedure has been shown to be effective in the removal of HIV. This term is sometimes referred to as ‘sperm washing’.

Sperm motility:

The percentage of moving spermatozoa relative to the total number of spermatozoa.

Sperm penetration assay (SPA):

A test where sperm are incubated with non-viable hamster eggs to determine the capacity of the sperm to fertilize.

Sperm recipient cycle:

A MAR cycle in which a woman receives spermatozoa from a person who is not her sexually intimate partner. In the case of ART registry data, a sperm recipient cycle would only include data from cycles using ART procedures.

Sperm vitality:

The percentage of live spermatozoa relative to the total number of spermatozoa.


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

Sperm analysis or sperm count:

Measures the quality and quantity as well as other parameters of semen that a man produces.

Spermatogenic arrest:

Failure of germ cells to progress through specific stages of spermatogenesis at onset or during meiosis.


The mature male reproductive cell produced in the testis that has the capacity to fertilize an oocyte. A head carries genetic material, a midpiece produces energy for movement, and a long, thin tail propels the sperm.

Spontaneous abortion/miscarriage:

The spontaneous loss of an intrauterine pregnancy prior to 22 completed weeks of gestational age.

Spontaneous reduction/vanishing sac(s):

The spontaneous disappearance of one or more gestational sacs with or without an embryo or fetus in a multiple pregnancy documented by ultrasound.


A permanent state of infertility.

Stillbirth rate:

The number of stillbirths per 1000 total births (stillbirths plus live births).


The death of a fetus prior to the complete expulsion or extraction from its mother after 28 completed weeks of gestational age. The death is determined by the fact that, after such separation, the fetus does not breathe or show any other evidence of life, such as heartbeat, umbilical cord pulsation, or definite movement of voluntary muscles. It includes deaths occurring during labor.


A term that should be used interchangeably with infertility.


Stimulation of the ovaries, usually done with hormones, that causes them to produce multiple eggs instead of one.


The process during which the female and male pronuclei fuse.




A reduced percentage of morphologically normal sperm in the ejaculate below the lower reference limits.

Testicular sperm aspiration/extraction (TESA/TESE):

The surgical removal of sperm directly from the testis or the epididymis using a needle for aspiration. This procedure is used for men who have no sperm in their ejaculates or have had vasectomies in the past. 


The process of raising the temperature of slow frozen cell(s) from the storage temperature to room/physiological temperature.

Time-lapse imaging:

The photographic recording of microscope image sequences at regular intervals in ART, referring to gametes, zygotes, cleavage stage embryos or blastocysts.

Total sperm count:

The calculated total number of sperm in the ejaculate.

Traditional gestational carrier:

A woman who donates her eggs and is the gestational carrier for a pregnancy resulting from fertilization of her eggs either through an ART procedure or insemination. 


Through the vagina.


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.

Tubal ligation:

A surgical procedure in which the fallopian tubes are surgically closed by cutting, clamping, banding, tying or sealing them to prevent pregnancy.

Tubal patency:

Lack of obstruction of the Fallopian tubes.

Tubal pathology:

Tubal abnormality resulting in dysfunction of the fallopian tube, including partial or total obstruction of one or both tubes. It usually occurs after pelvic inflammatory disease or pelvic surgery.




High-frequency sound waves that can be used painlessly, safely, and without radiation, to view the internal portions of the body. Ultrasound is especially useful for visualizing the female reproductive organs and pregnancies.

Unexplained infertility:

Inability to identify the cause of infertility despite a complete evaluation of semen, ovarian reserve, ovulation, endocrinologic disorders, and pelvic anatomy.


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. The majority of unisomies in human embryos are incompatible with life.


The reproductive organ that houses protects and nourishes the developing embryo and fetus. It consists of the cervix, the endometrium and the muscular layer that comprises the body of this reproductive organ.



Vaginal insemination:

A procedure whereby semen, collected from a non-lubricated condom or similar method, is deposited into the vaginal cavity of a female. An intervention that can be self-administered by a woman attempting pregnancy.


A varicose vein around the ductus (vas) deferens and the testes. This may be a cause of low sperm counts, motility and morphology and lead to male infertility. 


Procedure to remove part of the internal spermatic vein in situations in which it has expanded into a varicocele.


A surgical procedure for men that prevents sperm from reaching the urethra, making him sterile.


The description of the relative fluidity of the semen.


An ultra rapid cryopreservation procedure.



Warming cells:

The process of raising the temperature of a vitrified cell or cells from the storage temperature to room/physiological temperature.



Y chromosome microdeletions:

Missing segments of the genetic material on the Y chromosome that are associated with abnormal spermatogenesis.



Zona pellucida:

The glycoprotein coat surrounding the egg.

Zygote intrafallopian transfer (ZIFT):

An ART similar to IVF that involves removing sperm and eggs, combining them outside the body, and inserting fertilized eggs into the fallopian tubes.


A conceptus in which the genetic material (pronuclei) of the egg and sperm have united. A single cell resulting from fertilization of a mature oocyte by a spermatozoon and before completion of the first mitotic division. An early stage in the development of a fertilized egg.