Your IVF Glossary: 50 Terms You Will Hear at the Fertility Clinic

A to C

AFC (Antral Follicle Count): The number of small resting follicles visible on ultrasound at the start of your cycle. A higher count generally means more eggs can be recruited during stimulation. Normal AFC ranges from 10 to 25; below 5 is considered diminished ovarian reserve.

AMH (Anti-Mullerian Hormone): A blood test that estimates your ovarian reserve (how many eggs remain). AMH levels decline with age. Values above 1.0 ng/mL are generally considered normal; below 0.5 may indicate diminished reserve. AMH does not measure egg quality, only quantity.

Antagonist Protocol: The most common IVF stimulation protocol. Gonadotropin injections start on cycle day 2 or 3, and a GnRH antagonist (Cetrotide or Ganirelix) is added around day 5 to 7 to prevent premature ovulation. Shorter and simpler than the long lupron protocol.

Assisted Hatching: A lab technique where the embryologist thins or opens the zona pellucida (the shell around the embryo) before transfer, to help the embryo implant. Sometimes used for thawed embryos or patients over 38.

Beta (Beta hCG): The blood test that measures hCG levels to confirm pregnancy. "First beta" is the initial test, usually 9 to 12 days after a day-5 transfer. A "second beta" 48 hours later confirms the level is doubling appropriately.

Blastocyst: An embryo at day 5 or 6 of development, consisting of 100+ cells organized into an inner cell mass (which becomes the baby) and a trophectoderm (which becomes the placenta). Most transfers now happen at the blastocyst stage.

Chemical Pregnancy: A pregnancy that produces a positive beta hCG but ends before a gestational sac is visible on ultrasound (usually before 5 to 6 weeks). Included in some clinics' pregnancy rates but not in live birth rates.

D to F

Day 3 Embryo: An embryo at the cleavage stage, typically 6 to 8 cells. Some clinics transfer at day 3, though day 5 (blastocyst) transfer is now more common because it allows better embryo selection.

Day 5 Embryo: See Blastocyst.

Diminished Ovarian Reserve (DOR): A condition where the number of remaining eggs is lower than expected for age. Diagnosed by low AMH, low AFC, or elevated FSH. Does not mean pregnancy is impossible, but may mean fewer eggs per retrieval cycle.

Donor Eggs: Eggs from another person, used when the intended parent's own eggs are not viable. Donor egg IVF success rates are based on the donor's age, not the recipient's.

eSET (Elective Single Embryo Transfer): Transferring one embryo by choice (rather than because only one is available). Recommended by ASRM for most patients under 38 with good-quality blastocysts to reduce the risk of twins.

Estradiol (E2): A form of estrogen measured during monitoring. Rising estradiol levels indicate that follicles are growing and producing hormones. Very high levels may indicate risk for OHSS.

FET (Frozen Embryo Transfer): Transfer of a previously vitrified (frozen) embryo in a subsequent cycle. FET cycles use estrogen and progesterone to prepare the uterine lining without ovarian stimulation.

Follicle: A fluid-filled sac in the ovary that contains an egg. During stimulation, multiple follicles grow simultaneously. Not every follicle contains a mature egg.

FSH (Follicle-Stimulating Hormone): A natural hormone that stimulates follicle growth. Also the active ingredient in stimulation medications like Gonal-F and Follistim. Elevated baseline FSH (above 10 IU/L) may indicate diminished reserve.

G to L

Gestational Carrier (Surrogate): A person who carries a pregnancy for someone else. In gestational surrogacy, the embryo is created from the intended parents' or donors' eggs and sperm; the carrier has no genetic connection to the baby.

GnRH Agonist: A medication (such as Lupron) that initially stimulates and then suppresses the pituitary gland, preventing premature ovulation. Used in long lupron protocols and sometimes as a trigger shot.

GnRH Antagonist: A medication (Cetrotide or Ganirelix) that immediately blocks the pituitary from releasing LH, preventing premature ovulation. Used in antagonist protocols starting around stimulation day 5 to 7.

ICSI (Intracytoplasmic Sperm Injection): A fertilization technique where a single sperm is injected directly into a mature egg. Used for male factor infertility, low sperm counts, previous fertilization failure, or PGT testing.

Implantation: The process by which an embryo attaches to and embeds in the uterine lining. Occurs 6 to 10 days after ovulation or 1 to 5 days after a day-5 embryo transfer.

IUI (Intrauterine Insemination): A less invasive fertility treatment where washed sperm is placed directly into the uterus around the time of ovulation. Often tried before IVF. Success rates are lower (10% to 20% per cycle).

Long Lupron Protocol: A stimulation approach that starts with Lupron in the luteal phase of the cycle before treatment, suppressing the pituitary before starting gonadotropins. Takes longer than the antagonist protocol but gives some patients more even follicle growth.

M to P

MFM (Maternal-Fetal Medicine): A subspecialty of obstetrics that manages high-risk pregnancies, including IVF pregnancies with multiples or other complications.

Mock Transfer: A practice run of the embryo transfer procedure (without an actual embryo) to measure the uterine cavity and determine catheter placement. Usually done during an office visit before your cycle.

Morula: An embryo at day 4 of development, a solid ball of cells before it forms a cavity and becomes a blastocyst.

OHSS (Ovarian Hyperstimulation Syndrome): A potentially serious complication of ovarian stimulation where the ovaries swell and fluid leaks into the abdomen. Symptoms include severe bloating, rapid weight gain, nausea, and shortness of breath. Mild OHSS is common (up to 33% of cycles); severe OHSS requiring hospitalization occurs in 1% to 5%.

PGT-A (Preimplantation Genetic Testing for Aneuploidy): Testing embryos for the correct number of chromosomes (46) before transfer. A few cells are biopsied from the trophectoderm at the blastocyst stage. Euploid (chromosomally normal) embryos have higher per-transfer success rates.

PGT-M (Preimplantation Genetic Testing for Monogenic Disorders): Testing embryos for a specific genetic condition that one or both parents carry (such as cystic fibrosis, sickle cell disease, or BRCA mutations).

Progesterone: A hormone essential for maintaining the uterine lining and supporting early pregnancy. Supplemented after retrieval and through the first trimester via vaginal suppositories, intramuscular injections, or both.

R to Z

Retrieval (Egg Retrieval/Oocyte Pick-Up): The procedure where eggs are collected from the ovaries using a transvaginal ultrasound-guided needle under sedation. Takes 15 to 30 minutes.

SART (Society for Assisted Reproductive Technology): The professional organization that collects and publishes IVF outcome data from U.S. clinics. Their website (sart.org) allows you to compare clinic success rates.

Stim (Stimulation): Short for ovarian stimulation, the 10 to 14 day period of daily hormone injections that cause multiple follicles to grow.

Trigger (Trigger Shot): The final injection given 36 hours before retrieval to mature the eggs inside the follicles. Usually hCG (Ovidrel, Pregnyl) or Lupron.

TWW (Two-Week Wait): The period between embryo transfer and the first beta hCG blood test. Actually closer to 9 to 12 days for a day-5 transfer.

Vitrification: A rapid-freezing technique that prevents ice crystal formation in cells. Has dramatically improved survival rates for frozen eggs and embryos compared to older slow-freezing methods.

Zona Pellucida: The protective glycoprotein shell surrounding an egg and early embryo. Must be shed (hatched) before the embryo can implant in the uterine lining.

For more on the IVF process, explore our complete IVF guide collection.