Guide
Jargon buster
The words and abbreviations you'll hear at clinic, in plain English.
- AMH (anti-Müllerian hormone)
- A hormone made by small follicles in the ovaries. A blood test gives an estimate of egg reserve.
- Antral follicle count (AFC)
- The number of small resting follicles seen on a scan – another measure of egg reserve.
- Blastocyst
- An embryo at day 5–6, when most transfers and freezing happen.
- Cycle
- One round of treatment. In IVF, a 'full cycle' includes one egg collection and transfer of all resulting fresh and frozen embryos.
- DI / IUI-D
- Donor insemination – IUI using donor sperm.
- Egg sharing
- Donating some of your eggs during your own IVF in return for reduced-cost treatment.
- Embryo transfer
- Placing an embryo in the womb through a thin tube. No anaesthetic is usually needed.
- FET / FER
- Frozen embryo transfer / replacement.
- FSH
- Follicle-stimulating hormone – drives egg development. Also used as an injected IVF drug.
- HFEA
- Human Fertilisation and Embryology Authority – the UK regulator that licenses and inspects every fertility clinic.
- HyCoSy / HSG
- Tests to check your fallopian tubes are open, by ultrasound or x-ray.
- ICB
- Integrated Care Board – the NHS body that decides fertility funding in each part of England.
- ICSI
- Injecting a single sperm into each egg in the lab.
- IUI
- Intrauterine insemination – placing prepared sperm in the womb.
- IVF
- In vitro fertilisation – fertilising eggs with sperm in a lab.
- IVM
- In vitro maturation – collecting immature eggs and maturing them in the lab, with fewer drugs.
- Known donor
- Someone you know who donates sperm or eggs through a licensed clinic.
- Multiple birth
- Twins, triplets or more – the biggest health risk of fertility treatment.
- NICE
- National Institute for Health and Care Excellence – sets clinical guidelines for England and Wales.
- OHSS
- Ovarian hyperstimulation syndrome – an over-reaction to fertility drugs. Usually mild; occasionally serious.
- Parental order
- A court order that makes intended parents in surrogacy the legal parents.
- PCOS / PMOS
- Polycystic ovary syndrome, recently renamed polyendocrine metabolic ovarian syndrome – a common cause of irregular ovulation.
- PGT-A / PGT-M / PGT-SR
- Genetic testing of embryos for chromosome number, a single-gene condition or a structural rearrangement.
- Reciprocal IVF
- One partner's eggs are used and the other partner carries the pregnancy.
- Satellite clinic
- A smaller site linked to a licensed clinic, often doing consultations and scans nearer to home.
- Semen analysis
- A lab test of sperm count, movement and shape.
- Single embryo transfer (SET)
- Transferring one embryo to avoid twins. 84% of UK transfers in 2024.
- Stimulation
- Daily hormone injections to grow several eggs in an IVF or egg-freezing cycle.
- Transport clinic
- A site where treatment starts, with eggs or sperm transported to a licensed lab.
- Trigger injection
- The final injection that matures eggs before collection.
- Vitrification
- Very fast freezing that protects eggs and embryos from ice damage.