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Fertility and IVF glossary

Plain-language definitions of the terms you will hear from clinics, labs, and benefits teams.

A

Anti-Müllerian hormone (AMH): A hormone made by small follicles in the ovaries. A blood test for AMH gives an estimate of ovarian reserve: higher levels generally mean more remaining eggs, and lower levels mean fewer. Cleveland Clinic
Antral follicle count (AFC): The number of small, fluid-filled follicles seen in the ovaries on an ultrasound, usually early in a cycle. Along with AMH and FSH, it helps estimate ovarian reserve and how the ovaries may respond to IVF medications. SART / ASRM (ReproductiveFacts.org)
Assisted hatching: A lab technique that makes a small opening in the embryo's outer shell (zona pellucida) before transfer, intended to help the embryo hatch and implant. Evidence on its benefits and risks is mixed, so it is decided case by case. SART / ASRM (ReproductiveFacts.org)
Assisted reproductive technology (ART): Treatments and procedures that aim to achieve pregnancy, such as IVF. ART may be an option for people who have tried other infertility treatments without becoming pregnant. It is usually discussed with a fertility specialist. NICHD (NIH)

B

Blastocyst: An embryo that has developed for about five to six days after fertilization. It has an inner group of cells that can become a fetus and outer cells that can become the placenta. Many IVF clinics transfer embryos at this stage. Cleveland Clinic

C

Carrier screening: A genetic test, often done before treatment, that checks whether the egg or sperm source carries a recessive genetic condition that could be passed to a child. Results can help guide decisions such as embryo testing. SART / ASRM (ReproductiveFacts.org)

D

Deductible: The amount you pay for covered health care services before your insurance plan starts to pay. For fertility treatment, it helps to know how much of your deductible remains before a cycle begins. HealthCare.gov
Diminished ovarian reserve: A lower-than-expected number of eggs remaining in the ovaries. It is usually suggested by a high FSH level, a low AMH level, or a low antral follicle count, and may mean a weaker response to IVF medications. SART / ASRM (ReproductiveFacts.org)
Donor eggs: Eggs provided by another person, usually a younger, screened donor, for use in IVF. Donor eggs may be considered when egg quality or quantity is very low, after failed IVF cycles, or after cancer treatment. SART / ASRM (ReproductiveFacts.org)

E

Egg freezing: Collecting and freezing a person's eggs so they can try to have a biological child at a later date. It may be considered before some cancer treatments that can affect fertility, among other reasons. HFEA
Egg retrieval: A minor procedure to collect eggs from the ovaries during IVF, also called follicular aspiration. A thin needle is guided by ultrasound into each follicle. Medication is given so the person does not feel pain. MedlinePlus (NIH)
Elective single embryo transfer (eSET): A choice to transfer only one embryo during IVF, even when more are available. The main goal is to lower the risk of twins or triplets, which carry higher health risks for the pregnant person and babies. ASRM (ReproductiveFacts.org)
Embryo grading: The way an IVF lab rates an embryo's development. Blastocysts are graded on maturity, appearance, and cell number to help choose the embryo most likely to lead to a pregnancy. Grading is a guide, not a guarantee. Cleveland Clinic
Embryo transfer: The step in IVF when one or more embryos are placed into the uterus through a thin tube (catheter) passed through the cervix. It is usually done while the person is awake and takes only a few minutes. MedlinePlus (NIH)
Endometrial receptivity testing: A test that claims to find the best time to transfer an embryo by analyzing a sample of the uterine lining. The UK fertility regulator rates it red for most patients because evidence suggests it may reduce treatment effectiveness. HFEA

F

Fertility preservation: Freezing eggs, sperm, embryos, or reproductive tissue so a person can hopefully have a biological child later. It may be done before medical treatments that can affect fertility, such as chemotherapy or radiotherapy for cancer. HFEA
Frozen embryo transfer (FET): Thawing an embryo that was frozen during an earlier IVF cycle and placing it in the uterus. Frozen embryos can be used if a first transfer does not work or to try for another baby later. HFEA

G

Gestational carrier: A person who carries a pregnancy for someone else but has no genetic link to the baby, because the embryo is made with the intended parent's or a donor's egg. Arrangements involve medical, legal, and ethical steps. ASRM (ReproductiveFacts.org)

H

Hysterosalpingogram (HSG): An x-ray test that checks whether the fallopian tubes are open and whether the inside of the uterus looks normal. Dye is placed through the cervix. The outpatient procedure usually takes less than five minutes. ASRM (ReproductiveFacts.org)

I

In vitro fertilization (IVF): A type of assisted reproductive technology in which eggs are fertilized with sperm in a lab to create embryos, which can then be transferred to the uterus. It is used for many causes of infertility and other medical reasons. SART / ASRM (ReproductiveFacts.org)
Infertility: Not becoming pregnant after 12 months of regular unprotected intercourse, or after 6 months for women aged 35 and older. An evaluation may start sooner if age, medical history, or physical findings suggest a problem. ASRM (ReproductiveFacts.org)
Intracytoplasmic sperm injection (ICSI): An IVF lab technique in which a single sperm is injected directly into each egg to help fertilization. It is often used when sperm count or quality is low or when fertilization failed in an earlier cycle. ASRM (ReproductiveFacts.org)
Intrauterine insemination (IUI): A fertility treatment in which washed, concentrated sperm are placed directly into the uterus around the time of ovulation. It can use a partner's sperm or donor sperm, and is simpler and less invasive than IVF. HFEA

L

Lifetime maximum: A cap on how much a health plan will pay for a benefit over your lifetime. Some state fertility laws allow these caps; for example, Arkansas sets a $15,000 lifetime maximum for IVF, according to KFF. KFF
Luteal phase: The part of the menstrual cycle after ovulation and before the next period. It lasts about 14 days. It begins when the ovary releases an egg and ends when the next period starts. Cleveland Clinic

M

Mosaicism: When an embryo contains a mix of cells with a normal number of chromosomes and cells with an abnormal number. Genetic test results may be reported as mosaic. Such embryos may have a lower chance of pregnancy, and clinic practices vary. HFEA
Multiple pregnancy: A pregnancy with twins, triplets, or more. It is the main risk of fertility treatment and carries higher health risks for both the pregnant person and the babies. Transferring one embryo at a time lowers this risk. HFEA

O

Out-of-pocket maximum: The most you have to pay for covered services in a plan year. After you reach it, your plan pays 100% of covered costs. Fertility services that your plan does not cover usually do not count toward it. HealthCare.gov
Ovarian hyperstimulation syndrome (OHSS): A reaction that can occur in people taking fertility medicines that stimulate egg production. Most cases are mild, with bloating and mild belly pain. Rare severe cases can cause rapid weight gain or shortness of breath and are more serious. MedlinePlus (NIH)
Ovarian reserve: An estimate of how many eggs remain in the ovaries. It is commonly assessed with blood tests such as AMH and with an ultrasound follicle count. Ovarian reserve naturally declines with age. Cleveland Clinic
Ovarian stimulation: The phase of IVF in which fertility medications, usually injections containing FSH and/or LH, encourage several eggs to grow at once. It typically lasts 8 to 14 days and is tracked with ultrasounds and blood tests. ASRM (ReproductiveFacts.org)

P

Preimplantation genetic testing for aneuploidy (PGT-A): A test that checks a few cells from an embryo for an abnormal number of chromosomes. It can help rank embryos but cannot guarantee a pregnancy. The UK fertility regulator rates it red for improving birth rates for most patients. HFEA
Preimplantation genetic testing for monogenic conditions (PGT-M): A test on embryos created through IVF that looks for a specific inherited genetic condition known to run in a family, such as cystic fibrosis or sickle cell disease, so unaffected embryos can be chosen. SART / ASRM (ReproductiveFacts.org)
Prior authorization: Approval from a health plan that may be required before you get a service or fill a prescription for it to be covered. It is worth checking which fertility services and medications on your plan need it. HealthCare.gov

R

Recurrent implantation failure (RIF): When transfers of embryos thought to be viable repeatedly fail to lead to pregnancy, often enough for that person to warrant further investigation. ESHRE suggests considering testing once the predicted chance of implantation across those transfers was above 60%. ESHRE / Human Reproduction Open (PubMed)

S

Self-funded (self-insured) plan: A health plan, usually offered by larger employers, in which the employer pays employees' medical claims itself. These employers may contract with an insurer for services such as enrollment and claims processing. HealthCare.gov
Semen analysis: A lab test that measures the amount and quality of semen and sperm, including the number, movement (motility), and structure of sperm. It is usually one of the first tests in a fertility evaluation. MedlinePlus (NIH)
Single embryo transfer (SET): Transferring only one embryo during IVF. ASRM and SART guidelines recommend it when the eggs come from someone under 38 or the embryo has had genetic testing, to lower the chance of twins or triplets. SART / ASRM (ReproductiveFacts.org)
Society for Assisted Reproductive Technology (SART): The main US professional organization for IVF clinics. Member clinics are required to follow national guidelines, employ board-certified or board-eligible physicians, report outcomes accurately, and advertise truthfully. SART / ASRM (ReproductiveFacts.org)
State fertility mandate: A state law requiring certain health plans to cover, or to offer coverage for, some infertility treatments. Rules vary widely by state, and these laws do not apply to self-funded employer plans. KFF

T

Third-party reproduction: Fertility treatment that involves another person besides the intended parent or parents, such as an egg, sperm, or embryo donor, or a gestational carrier. SART / ASRM (ReproductiveFacts.org)
Time-lapse imaging: An incubator with a built-in camera that takes frequent pictures of embryos so the lab can track their development without removing them. The UK fertility regulator rates automated embryo analysis black, meaning evidence shows no effect on birth rates for most patients. HFEA
Treatment add-on: An optional extra offered alongside standard fertility treatment, such as certain embryo tests or special culture methods. For most people, routine proven treatment works without add-ons, so ask what evidence supports any extra. HFEA
Trigger shot: An injection given near the end of ovarian stimulation, once follicles are ready, to complete the final maturation of the eggs. Egg retrieval is scheduled for about 36 hours later, so the timing of this shot matters. Cleveland Clinic

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