IVF Glossary

aneuploid embryo

an embryo with more or fewer than the normal 46 chromosomes.

assisted reproductive technology (ART)

treatments that include the handling of eggs and/or embryos. Some ART procedures are in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), and zygote intrafallopian transfer (ZIFT).


the narrow, lower end of the uterus.

clomiphene citrate

an oral medication used to promote ovulation by causing the pituitary gland to release more follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

controlled ovarian stimulation (COS)

stimulation of the ovaries with medication to produce the development of multiple eggs rather than the single egg that normally develops each month.


the process of freezing embryos, eggs, or sperm at a low temperature to preserve for potential later use.

ectopic pregnancy

a pregnancy that occurs outside the uterus.

egg (oocyte)

the female sex cell (ovum) produced in the ovary that creates an embryo when fertilized by a male's sperm.

egg retrieval

a surgical procedure in which eggs are removed from the body with a thin needle.


a fertilized egg that has begun cell division.

embryo culture

the process of growing embryos within a laboratory.

embryo transfer

placement of an embryo into the uterus (in some ART processes, into the fallopian tube).


a disease in which the tissue of the uterine lining grows outside the uterus.


a form of estrogen (the most biologically active) produced by the follicular cells of the ovary.


a hormone that, in women, causes the uterine lining to thicken during the first half of the menstrual cycle in preparation for possible pregnancy.

euploid embryo

an embryo with the normal number of 46 chromosomes.

fallopian tubes

a pair of tubes attached to the uterus, one on each side, where sperm and egg meet in natural conception.


the fusion of sperm and egg, resulting in the formation of an embryo.


noncancerous tumors of the uterine wall.


a structure in the ovary containing an egg and the surrounding cells that produce hormones.

follicle-stimulating hormone (FSH)

a pituitary-produced hormone responsible for stimulating the growth of follicles, which contain eggs. In injectable gonadotropin medications, it is the hormone that promotes follicle growth.


one of the 2 reproductive cells (sperm or egg) that must unite to form an embryo.

gamete intrafallopian transfer (GIFT)

the direct transfer of sperm and eggs into the fallopian tube for fertilization in the body.

GnRH agonists

a GnRH analogue that triggers the pituitary gland to release LH and FSH. When started at the beginning of an IVF cycle, GnRH agonists also prevent premature ovulation and stimulate follicle growth.

GnRH antagonists

a GnRH analogue that is used to prevent premature ovulation in an IVF cycle. GnRH antagonists have an immediate suppressive effect on the pituitary gland, which prevents the release of LH and FSH.

gonadotropin-releasing hormone (GnRH)

a hormone secreted by the hypothalamus, a control center in the brain, which prompts the pituitary gland to release FSH and LH into the bloodstream.

human chorionic gonadotropin (hCG)

a hormone produced in the body; its detection is the basis for most pregnancy tests. hCG is also used to induce ovulation (also termed triggering ovulation) in an IVF cycle, and causes the final maturation of the egg. hCG trigger shots are given upon meeting certain criteria in an IVF cycle.

human menopausal gonadotropin (hMG)

a medication that contains FSH- and hCG-driven LH activity derived from the urine of postmenopausal women. hMG is used to stimulate the growth of multiple follicles.


a blocked, dilated, fluid-filled fallopian tube.

in vitro fertilization (IVF)

a process in which an egg and sperm are combined in a laboratory dish with the objective of fertilization to produce an embryo. If this occurs, the resulting embryo is transferred to the uterus.


the placement of sperm into the uterus or cervix with the intention of fertilization, or adding sperm to eggs in IVF procedures.

intracytoplasmic sperm injection (ICSI)

a procedure in which a single sperm is injected directly into an egg to attempt fertilization.

intramuscular (IM)

within the muscle.


a surgical procedure that allows viewing of the internal pelvic organs. During the procedure, a long, narrow, fiber-optic instrument called a laparoscope is usually inserted through an incision in or below the woman's navel.

luteinizing hormone (LH)

a pituitary-produced hormone that normally causes ovulation and maturation of the egg.

male factor

infertility caused by a problem in a male's reproductive system; for example, the inability to ejaculate or insufficient number of sperm.


the medical term for egg.

ovarian hyperstimulation syndrome (OHSS)

a condition in which the ovaries may become swollen, sometimes as a result of controlled ovarian stimulation (COS).

ovarian reserve

refers to the number of follicles (eggs) a woman has and is an indicator of her reproductive potential. Diminished ovarian reserve indicates depletion in the number of eggs.

ovary (ovaries)

the 2 female sex glands in the pelvis, located one on each side of the uterus. The ovaries produce eggs and hormones, including estrogen, progesterone, and androgens.


the release of an egg from the ovary (when the egg is expelled from the follicle).

pituitary gland

a small gland in the brain just beneath the hypothalamus that produces and secretes FSH, LH, and hCG.

polycystic ovary syndrome (PCOS)

a common endocrine disorder in women of reproductive age in which the body's sex hormones are not balanced, which may impair fertility.Characterized by enlarged ovaries with many antral follicles.

preimplantation genetic diagnosis (PGD)

a screening test used to determine if specific genetic or chromosomal disorders are present in embryos.

preimplantation genetic screening (PGS)

a test used to screen embryos for chromosome abnormalities.


a hormone that, in women, is secreted during the second half of the menstrual cycle and prepares the lining of the uterus for implantation of a fertilized egg.


the male reproductive cells that fertilize a woman's egg.

subcutaneous (SC)

underneath the skin.

transvaginal ultrasound aspiration

an ultrasound - guided technique for egg retrieval in which a needle is passed through the vagina into the ovarian follicle and suction is used to retrieve the egg.


a procedure utilized by fertility specialists to determine the health of female reproductive organs, monitor the growth of ovarian follicles, retrieve the eggs from the follicles, and evaluate a pregnancy.

uterus (womb)

the hollow, muscular female reproductive organ in the pelvis in which an embryo implants and grows during pregnancy.


the canal in the female body that leads to the cervix, which leads to the uterus.


a fertilized egg before cell division begins.

zygote intrafallopian tube transfer (ZIFT)

a procedure in which an egg is fertilized in the laboratory and the zygote is transferred to the fallopian tube before cell division takes place.

Adapted from Assisted Reproductive Technology: A Guide for Patients. American Society for Reproductive Medicine, 2011.