Fertility care comes with a vocabulary of its own, and most people meet it for the first time on a results sheet or in a consultation room. These are plain-language definitions of the terms you are most likely to hear, grouped by where they tend to come up.
This page explains what words mean. It does not interpret results — what any test or finding means for you is a conversation with your physician.
Testing and diagnosis
AMH (anti-Müllerian hormone)
A hormone produced by the small, developing follicles in the ovaries. Because the number of those follicles reflects how many eggs remain available, AMH is used as one marker of ovarian reserve. It is measured with a simple blood test that can be drawn at any point in the cycle.
FSH (follicle-stimulating hormone)
A hormone released by the pituitary gland that signals the ovaries to grow follicles. In men it supports sperm production in the testes. It is commonly measured early in the menstrual cycle as part of a fertility evaluation.
LH (luteinizing hormone)
Another pituitary hormone. A sharp rise in LH — the LH surge — triggers ovulation, which is why home ovulation predictor kits detect it in urine. In men, LH signals the testes to produce testosterone.
Estradiol
The main form of estrogen produced by growing ovarian follicles. Its level rises as follicles develop, so it is measured alongside ultrasound during a treatment cycle to track how the ovaries are responding. It is also checked at baseline as part of initial testing.
Progesterone
A hormone produced by the ovary after ovulation. It prepares the lining of the uterus to receive an embryo and helps maintain an early pregnancy. It can be measured in the blood and is often given as a medication during fertility treatment.
hCG (human chorionic gonadotropin)
The hormone produced by a developing pregnancy, and the hormone that pregnancy tests detect. A synthetic form is also used in fertility treatment as a trigger shot, because it mimics the natural LH surge that prompts eggs to mature and release.
Antral follicle count
A count of the small resting follicles visible on the ovaries during a transvaginal ultrasound, usually performed early in the cycle. Each of those follicles contains an immature egg. It is used together with AMH as a marker of ovarian reserve.
Ovarian reserve
A general term for the quantity of eggs remaining in the ovaries. It is estimated indirectly, most often with AMH and an antral follicle count. Ovarian reserve describes supply rather than egg quality, and no single measure of it defines a person's fertility.
Day 3 testing
Blood work drawn in the first few days of the menstrual cycle, counting the first day of full flow as day one. It typically includes FSH and estradiol, sometimes with other hormones. Testing at this point in the cycle gives a consistent baseline for comparison.
Baseline ultrasound
A transvaginal ultrasound performed at the start of a cycle, before any stimulation medication begins. It confirms the ovaries are quiet, checks the lining of the uterus, and allows an antral follicle count. It is the reference point against which later monitoring scans are compared.
HSG (hysterosalpingogram)
An X-ray test in which contrast dye is passed through the cervix into the uterus. It shows the shape of the uterine cavity and whether the fallopian tubes are open. It is one of the standard tests in a fertility evaluation.
Saline sonogram (SIS)
An ultrasound performed while sterile saline is gently instilled into the uterus. The fluid separates the walls of the cavity so that features such as polyps, fibroids or scar tissue become visible. It is sometimes called a sonohysterogram.
Semen analysis
A laboratory examination of a semen sample, and the first step in evaluating male fertility. It reports the volume of the sample and the concentration, motility (movement) and morphology (shape) of the sperm. Results are compared against published reference values.
WHO 6th edition (2021) reference values:
- Concentration: above 16 million sperm per millilitre
- Total motility: above 42%
- Progressive motility: above 30%
- Morphology (strict Kruger criteria): above 4% normal forms
These are statistical lower reference limits drawn from fertile men, not a pass/fail line — a single result below one of them is not a diagnosis of infertility.
Carrier screening
A blood or saliva test that looks for genetic changes a healthy person can carry without being affected themselves. It matters when both partners, or a patient and a donor, carry a change in the same gene. Results guide conversations with a genetic counselor.
Karyotype
A blood test that photographs a person's chromosomes to check their number and structure. Rearrangements that cause no symptoms in the person carrying them can still affect embryos. It is often ordered as part of an evaluation for recurrent pregnancy loss.
The IVF cycle
IVF (in vitro fertilization)
A treatment in which eggs are retrieved from the ovaries and combined with sperm in the laboratory. Any resulting embryos are grown for several days, then transferred into the uterus or frozen for later use. The full sequence, from stimulation to transfer, is called a cycle.
Ovarian stimulation
The phase of an IVF cycle in which injectable hormone medications encourage several follicles to grow at once, rather than the single follicle of a natural cycle. The dose and medications are chosen by the physician for each individual. Progress is followed with ultrasound and blood work.
Gonadotropins
The injectable hormone medications used for ovarian stimulation, containing FSH, LH activity, or both. They act directly on the ovaries to grow follicles. Which are used, and in what combination, is an individual clinical decision.
Monitoring
The series of short morning visits during a treatment cycle for blood work and ultrasound. They show how the follicles are growing and how hormone levels are changing, so medication can be adjusted and the retrieval timed. Monitoring visits usually happen every day or two during stimulation.
Trigger shot
A final injection given once the follicles have reached the size the physician is looking for. It prompts the eggs to complete maturation and loosen from the follicle wall, in the way a natural LH surge does. Egg retrieval is scheduled a set interval after it is given.
Egg retrieval
A short outpatient procedure, performed under sedation, in which a thin needle guided by ultrasound draws fluid from each follicle. The embryologist then locates the eggs in that fluid. Most people go home the same morning.
ICSI (intracytoplasmic sperm injection)
A laboratory technique in which a single sperm is injected directly into an egg, rather than sperm and egg being placed together in a dish. It is used when there are concerns about the sperm's ability to fertilize an egg, and in some other clinical situations. The decision to use it is made case by case.
Fertilization
The union of egg and sperm to form a single cell with genetic material from both. In IVF the laboratory checks the day after retrieval to see which eggs have fertilized normally. Not every egg retrieved will fertilize.
Embryo transfer
The placement of an embryo into the uterus through a thin, soft catheter passed through the cervix. It is usually quick, does not require sedation, and is guided by ultrasound. It can be done in the same cycle as the retrieval or in a later frozen cycle.
Fresh transfer
An embryo transfer performed in the same cycle as the egg retrieval, without freezing the embryo first. The lining of the uterus has been exposed to the hormones of stimulation. Whether a fresh transfer is appropriate is an individual clinical decision.
Frozen embryo transfer (FET)
The transfer of a previously frozen embryo, thawed on the day of the procedure. The cycle is prepared either with medication or by following the body's natural ovulation, so the lining of the uterus and the embryo are in step. Freezing allows transfers to be separated from the stimulation cycle.
Luteal phase support
Hormone medication, usually progesterone and sometimes estrogen, given after ovulation or transfer. It maintains the lining of the uterus during the window when an embryo may implant. It is typically continued into early pregnancy if a test is positive.
Natural cycle IVF
An IVF cycle that uses little or no stimulation medication, following instead the single follicle the body develops on its own. Fewer eggs are retrieved than in a stimulated cycle. Whether it suits a particular patient is a decision for the physician.
Minimal stimulation IVF
An IVF approach using lower doses of stimulation medication, often with oral agents, so fewer follicles are recruited. Fewer eggs are typically retrieved per cycle than with conventional stimulation. It is one of several approaches a physician may discuss.
IUI (intrauterine insemination)
A procedure in which prepared, washed sperm is placed directly into the uterus with a thin catheter, timed to ovulation. It is done in the office and is generally brief. It may be combined with medication to stimulate ovulation.
Ovulation induction
The use of medication to prompt the ovaries to release an egg in someone who ovulates irregularly or not at all. Oral or injectable medications may be used, with monitoring to follow the response. It can be paired with timed intercourse or with IUI.
OHSS (ovarian hyperstimulation syndrome)
An exaggerated response to stimulation medication in which the ovaries swell and fluid shifts into the abdomen. Symptoms range from bloating and discomfort to more serious illness requiring medical care. Monitoring and adjustments to medication and trigger are used to reduce the risk.
Embryos and genetics
Oocyte
The medical word for an egg — the reproductive cell produced by the ovary. Oocytes retrieved in an IVF cycle may be mature or immature, and only mature ones can be fertilized. You will see the term used throughout laboratory reports.
Blastocyst
An embryo that has developed to the stage where it has a fluid-filled cavity and two distinct cell groups: one that would become the fetus and one that would become the placenta. Embryos reach this stage several days after fertilization. Not all embryos develop to it.
Cleavage stage
The earlier stage of embryo development, before a blastocyst forms, when the embryo is dividing into a small cluster of cells. Embryos are sometimes transferred or assessed at this stage. Laboratory reports may describe cell number and appearance.
Embryo grading
The embryologist's visual assessment of an embryo's appearance under the microscope, describing features such as expansion and the look of the cell groups. Grading is descriptive, not a prediction for any individual embryo. Grading systems vary between laboratories.
Vitrification
A rapid freezing method that cools eggs or embryos so quickly that ice crystals do not form. It is the standard technique used in fertility laboratories today. Material frozen this way is stored in liquid nitrogen until it is needed.
Cryopreservation
The general term for freezing and storing eggs, sperm, embryos or ovarian tissue for future use. In fertility care it is used both within a treatment cycle and for planned preservation of fertility. Stored material remains frozen until it is thawed for use.
Assisted hatching
A laboratory technique in which a small opening is made in the outer shell surrounding an embryo before transfer. The intention is to help the embryo emerge from that shell. It is used selectively rather than routinely.
PGT-A (preimplantation genetic testing for aneuploidy)
Testing of a small number of cells biopsied from an embryo to assess whether it has the expected number of chromosomes. The embryo is frozen while results are pending. It is one option a physician and patient may consider together.
PGT-M (preimplantation genetic testing for monogenic conditions)
Testing of embryos for a specific inherited single-gene condition known to run in a family. It requires a test designed in advance for that family's particular genetic change. It is generally considered when carrier status or family history is known.
PGT-SR (preimplantation genetic testing for structural rearrangements)
Testing of embryos when a parent carries a chromosomal rearrangement, such as a translocation, in which chromosome material is positioned unusually. Carriers are often healthy themselves. The testing looks at whether an embryo inherited a balanced arrangement of that material.
Euploid
A term used after chromosome testing to describe an embryo found to have the expected number of chromosomes. It refers only to what that test examined. It is a laboratory result, not a guarantee about any pregnancy.
Aneuploid
A term used after chromosome testing to describe an embryo found to have a missing or extra chromosome. Aneuploidy is a common finding in human embryos and often prevents an embryo from developing. The result describes the embryo tested, not the person.
Mosaic embryo
An embryo whose biopsy showed a mixture of cells with and without the expected chromosome number. Because only a few cells are sampled, a mosaic result is an intermediate finding rather than a clear one. Decisions about mosaic embryos are made with the physician and a genetic counselor.
Conditions
PCOS (polycystic ovary syndrome)
A common hormonal condition associated with irregular or absent ovulation, signs of elevated androgen levels, and a characteristic ovarian appearance on ultrasound. Not everyone with the condition has all of these features. It is one of the more frequent reasons for difficulty conceiving.
Endometriosis
A condition in which tissue resembling the lining of the uterus grows outside the uterus, often on the ovaries, tubes or pelvic surfaces. It can cause pain, particularly around periods, and can affect fertility. Diagnosis and management are individual.
Diminished ovarian reserve
A term used when markers such as AMH and antral follicle count suggest fewer eggs remain available than expected. It describes the supply of eggs, not their quality, and it is not the same as being unable to conceive. What it means for any individual is determined by their physician.
Premature ovarian insufficiency
A condition in which the ovaries stop functioning as expected earlier in life than usual, causing irregular or absent periods and menopausal symptoms. Ovarian function can fluctuate rather than stop entirely. It is evaluated with hormone testing and, in some cases, genetic testing.
Unexplained infertility
The term used when a standard fertility evaluation — ovulation, tubes, uterus and semen analysis — comes back normal and no cause is identified. It means testing found no explanation, not that there is none. Treatment decisions are made on the overall picture.
Male factor infertility
Difficulty conceiving related to sperm number, movement, shape or delivery. It is identified through semen analysis and, where indicated, hormone testing and a urologic evaluation. It contributes to a substantial share of fertility evaluations.
Azoospermia
The absence of sperm in the ejaculated sample. It may be obstructive, where sperm are produced but cannot get out, or non-obstructive, where production itself is affected. Evaluation typically involves repeat testing, hormone levels and a urologist.
Oligospermia
A sperm concentration below the published reference value for the population studied. It is a description of one semen analysis result, not a diagnosis on its own. Because results vary between samples, testing is usually repeated.
Tubal factor infertility
Difficulty conceiving because one or both fallopian tubes are blocked or damaged, so egg and sperm cannot meet. Previous infection, surgery or endometriosis are among the causes. It is usually identified with an HSG or at surgery.
Hydrosalpinx
A fallopian tube that is blocked and filled with fluid. It is generally visible on ultrasound or an HSG. Management is discussed individually with the physician.
Uterine fibroids
Benign growths of muscle tissue in the wall of the uterus. They are common and often cause no symptoms, though depending on size and position they can cause bleeding or pressure, or distort the uterine cavity. Whether a fibroid needs treatment depends on where it sits.
Endometrial polyp
A small overgrowth of the lining of the uterus projecting into the cavity. Polyps are usually benign and are often found on a saline sonogram or hysteroscopy. They can sometimes be removed with a short outpatient procedure.
Recurrent pregnancy loss
Repeated miscarriage, evaluated as a distinct clinical problem rather than as separate events. Testing may look at chromosomes, the uterine cavity, hormones and clotting or immune factors. In many cases no single cause is identified.
Third-party reproduction
Donor egg
An egg provided by someone other than the person who will carry or parent the resulting child. Donors are screened medically, genetically and psychologically, and donation may be anonymous or known. The eggs are fertilized in the laboratory as part of an IVF cycle.
Donor sperm
Sperm provided by someone other than an intended parent, obtained through a sperm bank or from a known donor. Donors are screened and samples are typically quarantined and retested before use. Donor sperm can be used for IUI or for IVF.
Gestational carrier
A person who carries a pregnancy created from another person's or couple's egg and sperm, and who is not genetically related to the child. The arrangement involves legal agreements in place before treatment begins. Screening and counseling are part of the process.
Gestational surrogacy
The family-building path in which an embryo created through IVF is transferred to a gestational carrier. It is distinct from traditional surrogacy, in which the carrier's own egg is used. It is governed by state law and by contracts finalized in advance.
Reciprocal IVF
An option for some couples in which one partner provides the eggs and the other carries the pregnancy. Both partners take part in the physical process of building their family. It follows the usual IVF steps, divided between two people.
Outcomes and terms you'll hear
Implantation
The process by which an embryo attaches to the lining of the uterus and begins to establish a blood supply. It is what a positive pregnancy test reflects. It cannot be observed directly.
Clinical pregnancy
A pregnancy confirmed on ultrasound by the presence of a gestational sac, rather than by a blood or urine test alone. It is a defined milestone used consistently in fertility care and in reporting. It comes after the first positive hCG result.
Chemical pregnancy
A very early pregnancy loss in which hCG was detected but the pregnancy did not progress to being visible on ultrasound. The name refers to the pregnancy having been identified only by a hormone test. It is a common and recognized outcome.
Ectopic pregnancy
A pregnancy that implants outside the uterine cavity, most often in a fallopian tube. It cannot continue safely and requires prompt medical attention. Early monitoring with hCG levels and ultrasound is how it is usually identified.
Miscarriage
The loss of a pregnancy before it is able to survive outside the uterus. Most miscarriages happen early and are related to chromosomal changes in the embryo that arose by chance. A miscarriage is not caused by ordinary daily activity.
Live birth
The delivery of a baby showing signs of life. It is the outcome fertility care is aimed at, and the endpoint used in national reporting. A single delivery counts as one live birth even when more than one baby is born.
If a term you have been given is not here, or you would like someone to walk you through your results, get in touch with our office.