Antega United Kingdom · Learning Centre
A–Z Fertility Glossary
406 fertility terms explained in plain language.
406 terms
A
Fertilisation with an unexpected number of pronuclei, such as one or three.
Charges on top of the base price, such as ICSI, freezing or add-ons.
Uterine-lining-like tissue growing into the muscular wall of the uterus.
How drinking alcohol may affect conception and pregnancy.
Absence of periods.
A specialist in male reproductive health.
Having an extra or missing chromosome.
The absence of ovulation in a menstrual cycle.
A short IVF stimulation protocol using GnRH antagonists.
Anti-Müllerian hormone — a blood marker of ovarian reserve.
Immune proteins that attach to sperm and may reduce their movement.
A small, fluid-filled follicle visible on ultrasound early in the cycle.
Antral follicle count — an ultrasound-based estimate of ovarian reserve.
Scar tissue inside the uterus, often after surgery or infection.
Any treatment that helps conception happen with medical support.
Laboratory thinning of the embryo's outer shell.
Laboratory treatment to trigger egg activation after ICSI.
Treatments in which eggs or embryos are handled outside the body.
Lower-than-expected sperm movement.
No sperm present in the ejaculate.
B
A rearrangement where pieces of chromosomes swap places without loss of material.
Resting body temperature, which rises slightly after ovulation.
An ultrasound at the start of a cycle before medication begins or changes.
Blood test measuring pregnancy hormone hCG.
A very early pregnancy loss detected only by a pregnancy test.
An embryo at day 5–6 of development.
A single cell within a cleavage-stage embryo.
A fallopian tube that sperm or eggs cannot pass through.
Body Mass Index — a rough measure of weight relative to height.
A GnRH agonist used for down-regulation or as a trigger.
C
Guidance on caffeine when trying to conceive or pregnant.
A cycle stopped before egg collection or embryo transfer.
Testing whether someone carries a gene variant for an inherited condition.
Congenital bilateral absence of the vas deferens.
Vaginal secretion produced by the cervix.
The lower, narrow part of the uterus that opens into the vagina.
A GnRH antagonist that prevents early ovulation.
Testing for chlamydia before procedures on the uterus or tubes.
An abnormal number or structure of chromosomes.
A package of DNA carrying genes; most cells have 46.
Long-standing, low-grade inflammation of the uterine lining.
An embryo in the first days of cell division, before it compacts.
A clinic's reported chance of pregnancy or birth after treatment.
A donor recruited by a clinic or sperm/egg bank rather than known to you.
A pregnancy confirmed on ultrasound, usually by a gestational sac.
The proportion of cycles or transfers resulting in a clinical pregnancy.
An oral medication to induce ovulation.
Two or more people who are not in a relationship raising a child together.
When an embryo's cells press tightly together around day 3 to 4.
The start of a pregnancy, from fertilisation to implantation.
A difference in uterine shape present from birth.
Written agreement for eggs, sperm or embryos to be frozen and stored.
Your written agreement to the treatment you will receive.
The charge for appointments with a consultant.
IVF where sperm and eggs are placed together so fertilisation happens naturally in the dish.
Coenzyme Q10 — a supplement studied in egg and sperm quality.
The structure formed after ovulation that produces progesterone.
Freezing eggs, sperm or embryos for future use.
The chance of a live birth from all embryos from one egg collection, fresh and frozen.
What a clinic charges or refunds if a cycle is stopped.
The first day of full menstrual bleeding.
D
An embryo two days after egg collection, usually with around two to four cells.
A cleavage-stage embryo about 3 days after fertilisation.
A hormone sometimes used to support ovarian response.
The liquid used to dissolve a powdered medicine before injection.
Lower-than-expected egg supply for age.
The follicle that grows largest and releases an egg in a natural cycle.
The fixed payment UK donors can receive, set by the HFEA.
Having a child using donated eggs, sperm or embryos.
A donor's written consent to how their eggs, sperm or embryos may be used and stored.
An egg from another woman used in IVF.
A family created with the help of a donor.
Details about a donor that are recorded on the HFEA Register.
Insemination using donor sperm.
Sperm from a donor used in fertility treatment.
Someone conceived using donated eggs, sperm or embryos.
The rights of donor-conceived people to request information from the HFEA.
Temporarily switching off the natural hormone cycle before IVF stimulation.
E
Pregnancy loss in the first 12 to 13 weeks.
An NHS service assessing problems in early pregnancy.
A pregnancy implanted outside the uterus.
The procedure to collect eggs during IVF.
Medication given to keep you comfortable during egg collection.
Collecting and vitrifying eggs for future use.
How likely an egg is to fertilise and develop into a healthy embryo.
Donating some of your eggs during your own IVF in return for reduced-cost treatment.
Freezing all embryos for everyone, even without a medical reason.
A fertilised egg during early development.
When an embryo stops developing in the laboratory.
Removing a few cells from an embryo for genetic testing.
Growing embryos in an incubator in the laboratory.
An embryo whose cells break down and can no longer develop.
Donating embryos created during your own IVF so another person can use them.
Small pieces of cell material that break off in early embryos.
Vitrifying embryos created through IVF for later transfer.
A visual score for embryo quality.
Choosing which embryo to transfer or freeze first.
Keeping frozen embryos in a licensed centre.
Whether a frozen embryo remains viable once warmed.
How evenly sized the cells of an early embryo are.
Placing an embryo into the uterus.
The thin, soft tube used to place an embryo into the uterus.
Thawing a vitrified embryo in the laboratory before transfer.
A transfer medium enriched with hyaluronate.
A scientist specialising in embryo development.
A small overgrowth of the uterine lining.
Getting the uterine lining ready for an embryo transfer.
Endometrial receptivity analysis.
Deliberately irritating the uterine lining before a transfer.
How thick the uterine lining measures on ultrasound.
An ovarian cyst caused by endometriosis.
Uterine-lining-like tissue growing outside the uterus.
The lining of the uterus.
A coiled tube behind each testis where sperm mature.
An embryo tested as having the expected number of chromosomes.
How physical activity relates to fertility.
A blastocyst whose fluid cavity has grown and thinned the shell.
Growing embryos to the blastocyst stage (day 5 or 6).
F
The tube connecting the ovary to the uterus.
The chance of conceiving in a single menstrual cycle.
The biological capacity to produce a live birth.
Infertility where a cause relates to the ovaries, tubes or uterus.
The days in each cycle when sex can lead to pregnancy.
Fusion of sperm and egg.
The proportion of mature eggs that fertilise normally.
The ability to conceive a pregnancy and have a baby.
A centre providing fertility investigations and treatment.
The HFEA's regular review of licensed clinics.
Medicines used to stimulate the ovaries, control timing or support the lining.
Freezing eggs, sperm, embryos or tissue to allow the chance of having children later.
A doctor specialising in reproductive medicine.
An optional extra offered on top of standard treatment.
A non-cancerous growth of muscle in or around the uterus.
Cardiac activity seen on an early pregnancy scan.
A B vitamin that reduces the risk of neural tube defects.
A fluid-filled sac in the ovary containing an egg.
Follicle Stimulating Hormone.
The first part of the cycle, when a follicle grows before ovulation.
An IVF cycle in which all suitable embryos are frozen and none transferred fresh.
A treatment cycle including stimulation, egg collection and usually a fresh transfer.
Transferring an embryo in the same cycle as egg collection.
A cycle in which a previously frozen embryo is warmed and transferred.
Frozen Embryo Transfer.
G
Storing eggs or sperm in a licensed centre.
A GnRH antagonist supplied in pre-filled syringes.
Specialist support to understand inherited conditions and testing.
Testing DNA to detect inherited conditions.
The earliest immature egg stage, with a visible nucleus.
The first ultrasound-visible sign of pregnancy in the uterus.
Surrogacy where the embryo is created by IVF and the surrogate is not genetically related.
Gonadotrophin-Releasing Hormone.
A medicine that mimics GnRH, used to suppress the natural cycle or to trigger egg maturation.
A trigger using a GnRH agonist instead of hCG, often to reduce OHSS risk.
A medicine that blocks GnRH signalling to prevent early ovulation during IVF stimulation.
Treatment that may damage the ovaries or testes.
Injectable hormone used in fertility treatment.
Your GP sending you to a specialist fertility service.
H
A blastocyst that has fully left its shell.
A blastocyst starting to break out of its shell.
A trigger injection using hCG to mature eggs before collection.
How raised scrotal temperature can affect sperm production.
A pregnancy in the uterus and an ectopic pregnancy at the same time.
Permission granted by the HFEA for a centre to carry out specific activities.
The HFEA's confidential record of licensed treatments, donors and births.
The HFEA's traffic-light style summary of evidence for each add-on.
A UK clinic licensed by the HFEA to provide regulated treatments.
When many follicles develop during stimulation.
Human menopausal gonadotrophin — an injectable containing both FSH and LH activity.
Human Chorionic Gonadotrophin.
The UK regulator of fertility treatment.
A fluid-filled fallopian tube.
Elevated levels of prolactin.
Excessive ovarian response to stimulation.
Periods stop because the brain reduces its hormone signals to the ovaries.
The part of the brain that starts the hormonal signals controlling fertility.
Underactive thyroid gland.
An ultrasound test that checks the fallopian tubes using a contrast fluid.
Hysterosalpingogram — X-ray of the uterus and tubes.
Looking inside the uterus with a thin camera passed through the cervix.
I
Details that can identify a donor, such as name and last known address.
A donor whose identifying details can be requested by donor-conceived adults.
An egg not yet ready to be fertilised.
The embryo embedding into the uterine lining.
The proportion of transferred embryos that implant.
The limited time in each cycle when the lining is receptive to an embryo.
Frozen donor eggs from an overseas bank used at a UK clinic.
Donor sperm from an overseas bank used at a UK clinic.
ICSI with high-magnification sperm selection.
In Vitro Fertilisation.
Blood tests for infections such as HIV and hepatitis before treatment.
Not conceiving after regular unprotected sex for a year or longer.
Agreeing to treatment after understanding its purpose, risks and alternatives.
A health condition passed down through genes.
A multi-dose device for self-injecting fertility medicines.
The cluster of cells inside a blastocyst that becomes the baby.
The NHS body that plans and funds local health services in England.
A person who plans to raise a child born through surrogacy.
Intracytoplasmic Sperm Injection.
A fat emulsion given by drip, promoted to modify immune response.
A fibroid within the muscular wall of the uterus.
An injection given into a muscle.
Intrauterine Insemination.
One complete round of IVF, from starting medication to transfer or freezing.
K
L
Keyhole surgery to look at and treat pelvic organs.
Who the law recognises as a child's parents.
A first-line ovulation induction medication.
Raised white blood cells in semen.
Fertility care for lesbian, gay, bisexual, trans and queer people.
The sharp rise in luteinising hormone that triggers ovulation.
The birth of a baby showing signs of life.
Births divided by the number of embryos transferred.
The proportion of cycles, egg collections or transfers resulting in a live birth.
An IVF protocol using a GnRH agonist to switch off natural hormones before stimulation.
The second half of the menstrual cycle.
Hormone medication given after egg collection or embryo transfer to support the uterine lining.
Luteinising Hormone.
M
Infertility where a cause relates to sperm or the male reproductive system.
The age of the person providing the eggs or carrying the pregnancy.
An egg that has reached the stage where it can be fertilised.
Preservation because a medical treatment or condition may affect fertility.
A medicated frozen embryo transfer protocol.
The price of fertility medicines, often charged separately.
Keeping fertility medicines at the correct temperature.
The cell division that produces eggs and sperm with half the usual chromosomes.
Another name for human menopausal gonadotrophin (hMG).
The monthly hormonal cycle that prepares an egg and the uterine lining.
Microsurgical epididymal sperm aspiration.
An intermediate egg stage between GV and mature.
The mature egg stage, ready for fertilisation.
A diabetes medicine sometimes used in PCOS.
Microsurgical TESE using an operating microscope.
Testing bacteria in the vagina or uterus to guide treatment.
A blood test about a week before a period to check whether ovulation happened.
IVF using lower doses of stimulation medicines.
Pregnancy loss before 24 weeks.
A pregnancy that has stopped developing without bleeding or pain.
One-sided pelvic pain some people feel around ovulation.
A practice transfer with no embryo, to check the route into the uterus.
A natural-cycle FET that uses a trigger injection or some medication to time ovulation.
A compact ball of cells formed around day 4.
An embryo in which the biopsy showed a mix of normal and abnormal cells.
A package covering several IVF cycles for a set price.
Being pregnant with twins, triplets or more.
N
IVF without ovarian stimulation.
A frozen embryo transfer timed to your own ovulation, without oestrogen tablets.
A high proportion of dead sperm in the sample.
The local rules that decide who can have NHS-funded treatment.
The queue for NHS fertility appointments or treatment.
Fertility investigations and treatment paid for by the NHS.
IVF paid for by the NHS for people who meet local criteria.
National recommendations on assessing and treating fertility problems.
Details about a donor that do not reveal who they are.
No sperm in the ejaculate because of a sperm production problem.
Sperm moving but not travelling forward.
Fertilisation producing an egg with two pronuclei.
O
No sperm in the ejaculate because of a blockage.
The main form of oestrogen, measured in blood tests during treatment.
A group of hormones that build the uterine lining and regulate the cycle.
Ovulating infrequently or irregularly.
Low count, reduced movement and fewer normally shaped sperm together.
Infrequent periods, usually cycles longer than 35 days.
A lower sperm count than the reference range.
Fertility care for people with cancer.
A pregnancy continuing beyond the early weeks, often past 10 to 12 weeks.
The proportion of cycles or transfers leading to an ongoing pregnancy.
An egg cell.
Ovarian Hyperstimulation Syndrome.
The remaining pool of eggs in the ovaries.
IVF injectable phase to grow multiple follicles.
Freezing strips of ovarian tissue for later re-implantation.
One of two organs that store eggs and produce oestrogen and progesterone.
Release of a mature egg from the ovary.
Medication to stimulate ovulation.
A home urine test that detects the LH surge.
Monitoring signs, tests or scans to identify when ovulation occurs.
An imbalance that can damage sperm cells and their DNA.
P
A court order transferring legal parenthood from the surrogate to the intended parents.
Consent forms that give an unmarried partner legal parenthood after licensed treatment.
The age of the sperm provider.
Infection of the upper reproductive tract.
Success measured per cycle started or per egg collection.
Success measured per embryo transfer procedure.
Percutaneous epididymal sperm aspiration — collecting sperm from the epididymis with a needle.
Preimplantation genetic testing for aneuploidy.
Preimplantation genetic testing for monogenic conditions.
Preimplantation genetic testing for structural rearrangements.
Physiologic ICSI using hyaluronic acid binding.
A small gland at the base of the brain.
A small cell released by the egg during maturation.
Polycystic Ovary Syndrome.
When the ovaries produce fewer follicles than expected during stimulation.
A urine or blood test detecting hCG after treatment.
Using gametes or embryos after the person who provided them has died.
A single-dose syringe supplied ready to inject.
The time before trying to conceive or starting treatment.
Health steps before pregnancy to support you and a future baby.
The end of a pregnancy that does not result in a live birth.
A positive test where the pregnancy cannot yet be seen on scan.
Laboratory testing of pregnancy tissue, often to look at chromosomes.
Testing cells from IVF embryos before transfer.
Loss of normal ovarian function before the age of 40.
Ovulation happening before planned egg collection.
Difficulty conceiving when there has been no previous pregnancy.
Treatment you pay for yourself at a licensed clinic.
Medical term for pregnancy tissue after a miscarriage.
A hormone that supports the uterine lining.
Progesterone given by subcutaneous or intramuscular injection.
Progesterone inserted into the vagina or rectum for luteal support.
Sperm moving actively forward.
A pituitary hormone involved in reproduction and lactation.
The nucleus from the egg or the sperm visible after fertilisation.
A gland below the bladder that adds fluid to semen.
Platelet-rich plasma injected into the ovaries or uterus.
The price a clinic advertises for a treatment.
R
When one partner provides the eggs and the other carries the pregnancy.
Laboratory-made FSH used for ovarian stimulation.
Losing three or more pregnancies in a row, or as locally defined.
A package where part of the fee is refunded if treatment doesn't lead to a birth.
The years during which someone can conceive naturally.
The gradual decline in fertility with age.
Tests and treatments based on theories about the immune system and implantation.
Semen flowing backwards into the bladder instead of out.
A check for protection against German measles before pregnancy.
S
An ultrasound with saline to outline the inside of the uterus.
Routes to parenthood for same-sex couples.
The skin pouch holding the testes.
A referral from primary care (your GP) to a hospital or specialist clinic.
Difficulty conceiving after a previous pregnancy.
The fluid ejaculated, containing sperm and fluids from the glands.
A test of sperm count, motility and morphology.
Glands that produce most of the fluid in semen.
Tiny tubes inside the testes where sperm are made.
A puncture-proof container for used needles.
An IVF protocol that starts stimulation at the beginning of the cycle.
Transferring one embryo at a time.
The relationship between sleep and reproductive health.
How smoking affects the chances of conceiving.
Choosing to become a parent without a partner.
The male reproductive cell that fertilises an egg.
The number of sperm per millilitre of semen.
Damage to DNA within sperm.
Storing sperm samples at very low temperatures.
Shape of sperm.
Movement of sperm.
The proportion of sperm that are alive.
The process of producing sperm in the testes.
Light bleeding outside a normal period.
Using corticosteroids such as prednisolone during treatment.
When a baby dies in the womb after 24 weeks of pregnancy.
The ongoing charge for keeping eggs, sperm or embryos frozen.
How long eggs, sperm or embryos may lawfully be stored.
Confirming you want stored material kept for a further period.
How stress relates to trying to conceive and treatment.
An injection given into the fatty layer just under the skin.
Reduced fertility — taking longer than expected to conceive.
A fibroid bulging into the uterine cavity.
A fibroid on the outer surface of the uterus.
Surgical Sperm Retrieval.
When someone carries a pregnancy for intended parents.
An arrangement setting out the intentions of surrogate and intended parents.
The person who carries a pregnancy for intended parents.
T
The UK limit on how many families one donor can help create.
A low percentage of normally shaped sperm.
Testicular sperm aspiration — collecting sperm from the testis with a needle.
Testicular sperm extraction — removing small samples of testicular tissue to find sperm.
Freezing testicular tissue, mainly for boys before puberty.
One of two glands producing sperm and testosterone.
The primary male sex hormone.
Blood test measuring thyroid hormones.
Continuous imaging of embryos in the incubator.
When none of the eggs fertilise in an IVF or ICSI cycle.
The number of moving sperm in the whole sample.
The total number of sperm in the whole ejaculate.
Surrogacy where the surrogate's own egg is used.
Freezing eggs, sperm or tissue before gender-affirming treatment.
An internal ultrasound using a slim probe in the vagina.
A bundle of treatment steps sold for one price.
A written estimate of the cost of your personal treatment plan.
Injection that matures eggs before collection.
A layered appearance of the lining on ultrasound before ovulation or progesterone.
The outer layer of a blastocyst.
Actively trying to become pregnant.
Infertility caused by damaged or blocked fallopian tubes.
The sign of normal fertilisation checked the day after egg collection.
The wait between transfer and pregnancy test.
U
Serial scans during IVF stimulation.
Infertility with no cause identified on standard tests.
A band of tissue dividing the uterine cavity, present from birth.
The organ where pregnancy develops.
V
What is known about e-cigarettes and fertility.
Enlarged veins in the scrotum.
The tube carrying sperm from the epididymis towards the urethra.
An early ultrasound to check the pregnancy is in the uterus and developing.
A small glass container of powder or liquid medicine.
A vitamin important for bones and general health.
Ultra-rapid freezing of eggs and embryos.
W
How body weight can affect ovulation, sperm and treatment.
A clinic's legal duty to consider the welfare of any child born from treatment.
Changing or cancelling consent you have given.
A donor's right to change or withdraw consent before gametes or embryos are used.