Plain-language definitions
Every fertility term, explained clearly.
A reference glossary of fertility, IVF and reproductive-medicine terms — so you can read your reports, understand your treatment plan and ask better questions.
Medically reviewed by Dr. Shweta Agarwal, MBBS, DGO · Last updated June 2026
Govt. ART-registered
ART Level 2 RegisteredGovt. of India — ART Act 2021
Dr. Shweta AgarwalMBBS, DGO · Reproductive Medicine
On-site embryology labLed by Aayush Agarwal, Ph.D.
Marathi · Hindi · EnglishChandrapur · Nagpur · Vidarbha
This glossary defines 55 terms used in fertility medicine and assisted reproduction — from hormone markers such as AMH and FSH, to laboratory techniques such as ICSI and vitrification, to regulatory terms under India's ART Act 2021. Definitions are written in plain language and reviewed by Dr. Shweta Agarwal, MBBS, DGO, Lead Fertility Specialist at Aansh Hospital & IVF Center. Use the group headings to navigate, or use your browser's search (Ctrl / Cmd + F) to find a specific term.
Hormones & Ovarian Reserve
- AMH (Anti-Müllerian Hormone)
- A hormone produced by small follicles in the ovary; its blood level is the most reliable single marker of a woman's remaining egg supply (ovarian reserve).
- AFC (Antral Follicle Count)
- The number of small resting follicles (2–10 mm) counted by ultrasound early in a menstrual cycle; used alongside AMH to estimate ovarian reserve and predict response to fertility stimulation.
- AMH vs AFC
- AMH is a blood test that can be taken on any day of the cycle; AFC is an ultrasound count taken on cycle days 2–4. Together they provide a more complete picture of ovarian reserve than either test alone.
- FSH (Follicle-Stimulating Hormone)
- A pituitary hormone that stimulates ovarian follicle growth each cycle. An elevated basal FSH level (day 2–3) often signals declining ovarian reserve; in men, FSH regulates sperm production.
- LH (Luteinising Hormone)
- A pituitary hormone whose mid-cycle surge triggers ovulation. Elevated resting LH is common in PCOS; LH is also measured in timed intercourse and IUI cycles to identify the fertile window.
- Estradiol (E2)
- The primary oestrogen produced by growing follicles; levels rise through the follicular phase, trigger the LH surge, and are monitored throughout IVF stimulation to track follicle development.
- Progesterone
- A hormone produced by the corpus luteum after ovulation that prepares the uterine lining for embryo implantation; given as vaginal pessaries or injections during IVF luteal-phase support.
- Ovarian Reserve
- The quantity and quality of a woman's remaining egg supply, assessed using AMH, AFC and basal FSH. Reserve naturally declines with age and can be reduced by surgery, endometriosis or genetic conditions.
Diagnostics & Tests
- Semen Analysis
- A laboratory test measuring sperm count (concentration), motility (movement), morphology (shape) and volume, assessed against WHO 2021 reference values; the essential first investigation for male-factor infertility.
- HSG (Hysterosalpingography)
- An X-ray procedure in which contrast dye is injected into the uterine cavity to outline its shape and check whether the fallopian tubes are open (patent) or blocked.
- Hysteroscopy
- A minimally invasive procedure in which a thin camera is passed through the cervix to directly visualise the inside of the uterus, diagnose polyps, fibroids or adhesions, and perform surgical correction if needed.
- Laparoscopy
- A keyhole surgical procedure in which a camera is inserted through a small abdominal incision to inspect the pelvis; used to diagnose and treat endometriosis, ovarian cysts, adhesions and blocked tubes.
- Sonohysterography / HyCoSy
- An ultrasound-based procedure in which saline (sonohysterography) or foam contrast (HyCoSy) is instilled into the uterus to evaluate the uterine cavity and assess tubal patency without radiation.
- Follicular Tracking
- Serial transvaginal ultrasound scans performed through the menstrual cycle to monitor follicle growth, estimate the time of ovulation, and guide the timing of intercourse, IUI or egg retrieval.
- Karyotype
- A laboratory test that photographs and analyses all 46 human chromosomes from a blood sample; performed to identify chromosomal causes of recurrent pregnancy loss, azoospermia or failed IVF cycles.
- DFI (Sperm DNA Fragmentation Index)
- A test measuring the percentage of sperm with damaged DNA strands; elevated DFI (typically >25–30 %) is associated with reduced fertilisation, poor embryo quality and recurrent pregnancy loss.
Procedures & Treatments
- IVF (In Vitro Fertilisation)
- An assisted reproduction procedure in which the ovaries are stimulated with hormonal injections, mature eggs are retrieved, fertilised with sperm in the embryology laboratory, and the resulting embryo is transferred into the uterus.
- IUI (Intrauterine Insemination)
- A fertility procedure in which washed, concentrated sperm are placed directly into the uterine cavity around the time of ovulation, shortening the distance sperm must travel to reach the egg.
- ICSI (Intracytoplasmic Sperm Injection)
- An IVF technique in which a single sperm is injected directly into a mature egg using a microscopic needle; the standard approach when sperm count, motility or morphology is significantly reduced.
- IMSI (Intracytoplasmic Morphologically Selected Sperm Injection)
- An advanced form of ICSI using high-magnification microscopy (×6,000) to select sperm with the most normal internal structure before injection, typically used after repeated ICSI failure or severe male-factor infertility.
- Ovulation Induction (OI)
- The use of oral medications (such as letrozole or clomiphene) or low-dose injectable hormones to stimulate the development of one or two follicles in women who do not ovulate regularly.
- Egg Retrieval (OPU — Oocyte Pick-Up)
- A minor surgical procedure performed under sedation in which a fine needle is guided by transvaginal ultrasound through the vaginal wall to aspirate mature eggs from the ovarian follicles.
- Embryo Transfer (ET)
- The final step of an IVF cycle in which one or more embryos are placed into the uterine cavity via a thin catheter, usually 3 or 5 days after egg retrieval, under ultrasound guidance.
- FET (Frozen Embryo Transfer)
- A procedure in which previously vitrified (frozen) embryos are thawed and transferred into the uterus in a subsequent cycle, allowing the body to recover from stimulation before implantation.
- Blastocyst Culture
- Extending embryo culture in the laboratory to day 5–6 so embryos reach the blastocyst stage, at which point embryo quality and implantation potential can be assessed more accurately than at the cleavage stage.
- Assisted Hatching
- A laboratory technique in which a small opening is made in the zona pellucida (outer shell) of an embryo using a laser or acid, intended to assist the embryo in hatching and attaching to the uterine lining.
- PGT-A (Preimplantation Genetic Testing for Aneuploidies)
- Chromosomal screening of embryo biopsies before transfer to identify embryos with the correct number of chromosomes (euploid), improving the likelihood of successful implantation. PGT-A tests for chromosomal health only; sex selection for non-medical purposes is prohibited by law in India and is not offered.
- PGT-M (Preimplantation Genetic Testing for Monogenic Disorders)
- Genetic testing of embryo biopsies for a specific inherited single-gene disorder (such as thalassaemia or sickle-cell anaemia) in couples known to be carriers, allowing transfer of unaffected embryos.
- Egg Freezing (Oocyte Cryopreservation)
- The vitrification and storage of mature unfertilised eggs for future use, enabling women to preserve fertility before cancer treatment, surgery or age-related decline.
- Embryo Freezing (Embryo Cryopreservation)
- The vitrification and long-term storage of surplus embryos created during an IVF cycle, allowing additional transfer attempts without the need for repeat stimulation and egg retrieval.
- Sperm Freezing (Sperm Cryopreservation)
- The processing and storage of sperm in liquid nitrogen for future use in IUI, IVF or ICSI; used before cancer treatment, during surgical sperm retrieval or when the male partner cannot produce a sample on the day of retrieval.
- TESA / PESA / TESE
- Surgical sperm retrieval procedures: TESA (testicular sperm aspiration) uses a fine needle; PESA (percutaneous epididymal sperm aspiration) aspirates from the epididymis; TESE (testicular sperm extraction) retrieves tissue surgically — all used when no sperm are present in the ejaculate (azoospermia).
Embryology & Lab
- Oocyte
- The scientific term for a human egg cell. During an IVF cycle, mature metaphase II oocytes (MII) are retrieved from the follicles and used for fertilisation by conventional insemination or ICSI.
- Blastocyst
- An embryo at day 5–6 of development containing approximately 100–200 cells, divided into an inner cell mass (which becomes the fetus) and a trophectoderm (which becomes the placenta).
- Embryo Grading
- A system used by embryologists to assess embryo quality and guide transfer selection. Cleavage-stage embryos are graded by cell number and fragmentation; blastocysts by expansion, inner cell mass and trophectoderm quality.
- Vitrification
- An ultra-rapid cryopreservation technique that converts biological material (eggs, embryos or sperm) to a glass-like solid, preventing the formation of ice crystals that damage cells during conventional slow freezing.
- Fertilisation
- The fusion of a sperm cell with an egg to form a zygote, confirmed in the IVF laboratory 16–18 hours after insemination or ICSI by the appearance of two pronuclei (2PN).
- Cleavage Stage Embryo
- An embryo on day 2–3 of development, typically comprising 4–8 cells. Cleavage-stage embryos can be transferred or cultured further to the blastocyst stage before transfer.
- Time-Lapse Imaging (EmbryoScope)
- A continuous embryo monitoring system that photographs embryos every 10–20 minutes inside the incubator, allowing embryologists to observe every cell division without disturbing the culture environment.
Conditions
- PCOS (Polycystic Ovary Syndrome)
- A hormonal condition characterised by irregular ovulation, elevated androgens and polycystic-appearing ovaries on ultrasound; one of the most common causes of ovulatory infertility in women.
- Endometriosis
- A condition in which tissue similar to the uterine lining grows outside the uterus, causing inflammation, adhesions and pain; associated with reduced fertility through effects on egg quality, tube function and implantation.
- Azoospermia
- The complete absence of sperm in the ejaculate, classified as obstructive (a blockage preventing sperm release) or non-obstructive (impaired sperm production); treatable in many cases with surgical sperm retrieval and ICSI.
- Oligospermia
- A lower-than-normal sperm concentration in the ejaculate (below 16 million/mL per WHO 2021); mild, moderate or severe grades guide whether IUI, IVF or ICSI is recommended.
- Low AMH / DOR (Diminished Ovarian Reserve)
- A reduced egg supply relative to age, indicated by low AMH, low AFC or elevated FSH; does not mean natural conception is impossible, but typically means fewer eggs are retrieved in an IVF cycle.
- POI (Premature Ovarian Insufficiency)
- The loss of normal ovarian function before the age of 40, characterised by irregular or absent periods, low AMH, high FSH and oestrogen deficiency; formerly called premature ovarian failure.
- Unexplained Infertility
- A diagnosis given when standard investigations — ovulation assessment, tubal patency, semen analysis and uterine evaluation — all return normal results but pregnancy has not occurred after 12 months of regular unprotected intercourse.
- Recurrent Pregnancy Loss (RPL)
- Conventionally defined as two or more pregnancy losses; investigated for chromosomal, uterine, thrombotic, immunological and hormonal causes. Couples with RPL benefit from a structured evaluation before further attempts.
- Recurrent Implantation Failure (RIF)
- The failure to achieve a clinical pregnancy after multiple embryo transfers of good-quality embryos; triggers investigation of uterine, immunological, thrombophilic and embryo factors before further treatment.
- Hydrosalpinx
- A blocked, fluid-filled fallopian tube resulting from prior infection, surgery or endometriosis; the fluid can impair IVF implantation, and surgical removal (salpingectomy) is often recommended before an IVF cycle.
- Thin Endometrium
- A uterine lining that fails to thicken to the 7–8 mm typically considered adequate for implantation; causes include poor blood flow, prior surgery (Asherman's syndrome) or insufficient oestrogen stimulation.
Regulatory & Care
- ART Act 2021 (ART Regulation Act)
- India's Assisted Reproductive Technology (Regulation) Act, 2021, which mandates registration of all ART clinics and banks, sets standards for laboratory, consent and record-keeping, and places the sector under the National ART & Surrogacy Registry.
- ART Level 2 Clinic
- A classification under the ART Act 2021 authorising a clinic to perform advanced procedures including IVF and ICSI. Level 1 clinics may legally provide only IUI. Aansh Hospital & IVF Center holds a government-issued Level 2 registration.
- ART Bank
- A facility registered under the ART Act 2021 to lawfully screen, process and store gametes (eggs and sperm) and embryos, including for a compliant donor program. Aansh holds ART Bank registration.
- Egg Donor (Donor Oocyte)
- A woman who donates her eggs to help another person conceive, under the regulated framework of India's ART Act 2021. Donor-egg IVF is used when a patient's own eggs cannot yield a viable pregnancy. This page is educational; donor programs must comply fully with ART Act 2021 regulations.
- Sperm Donor
- A man who provides sperm for use in assisted reproduction for another individual or couple, under the regulated framework of India's ART Act 2021. This page is educational; all donor procedures at Aansh comply with ART Act 2021 regulations.
Medical note: Information on this page is educational and does not replace a medical consultation. Outcomes depend on individual clinical factors. Last updated June 2026. Reviewed by Dr. Shweta Agarwal, MBBS, DGO.
Good to know
Frequently asked questions about fertility terms
What is AMH and why is it tested?
AMH (Anti-Müllerian Hormone) is a blood test that measures ovarian reserve — the remaining supply of eggs in the ovaries. It can be taken on any day of the menstrual cycle and is used alongside an ultrasound antral follicle count (AFC) to estimate how many eggs are likely to be retrieved in an IVF cycle. A low AMH does not rule out natural pregnancy or IVF, but it does influence the stimulation protocol your doctor chooses.
What is the difference between IVF and ICSI?
In conventional IVF, eggs and sperm are placed together in a dish and fertilisation occurs naturally. In ICSI (intracytoplasmic sperm injection), a single sperm is injected directly into each mature egg using a micro-needle — a technique recommended when sperm count, motility or morphology is significantly reduced, or after previous fertilisation failure. The stimulation, egg retrieval and embryo transfer steps are identical; only the fertilisation method differs. See also: IVF vs ICSI — when is ICSI needed?
What is a blastocyst and why does it matter for IVF?
A blastocyst is an embryo at day 5–6 of development, containing roughly 100–200 cells and a fluid-filled cavity. Culturing embryos to the blastocyst stage before transfer (rather than day 3 cleavage stage) allows the embryology team to select the embryos most likely to implant, as weaker embryos often stop developing between days 3 and 5. Blastocyst transfer is associated with higher implantation rates per transfer in most patient groups.
What is PGT-A and does Aansh offer sex selection?
PGT-A (Preimplantation Genetic Testing for Aneuploidies) is a technique that biopsies a few cells from a blastocyst and analyses them for chromosomal abnormalities. The goal is to identify chromosomally normal (euploid) embryos before transfer, reducing the risk of implantation failure and miscarriage. PGT-A tests chromosomal health only. Sex selection for non-medical purposes is prohibited by law in India under the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act and the ART Act 2021. Aansh does not offer or facilitate sex selection under any circumstances.
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