Fertility Glossary: Acronyms, Tests & Treatments Explained
Trying to conceive can sometimes feel like stepping into a world with its own language. This fertility glossary breaks down the terms, acronyms, and medical jargon you’re most likely to come across, so you can feel informed and confident in your next steps.
Author
Tassia O’Callaghan
Reviewed by
Kayleigh Hartigan
19 min read
Updated 30th September 2025
Community terms and acronyms
When you’re part of the TTC community, you’ll quickly notice a language of its own. From acronyms like DPO or TWW to phrases like “baby dust,” these shorthand terms make it easier to share experiences — but they can feel confusing at first. Here we break them down so you can feel at home in the conversation.
- AF: “Aunt Flo,” slang for period.
- BBT: Basal Body Temperature — your resting body temperature, tracked daily to detect ovulation.
- BD: “Baby Dance,” slang for sex when trying to conceive in many fertility forums. Could also be “Baby Dust,” wishing someone luck while trying to conceive.
- CD: Cycle Day — the numbered day of your menstrual cycle (CD1 = first day of bleeding).
- DPO: Days Past Ovulation — how many days since ovulation occurred, often used to refer to when to take a pregnancy test (e.g. 14 DPO as the typical day).
- FRER: First Response Early Result pregnancy test — one of the more sensitive home pregnancy tests for detecting hCG, the pregnancy hormone.
- HFEA: Human Fertilisation and Embryology Authority — the UK regulator of fertility clinics.
- HPT: Home Pregnancy Test — a test used at home to detect hCG (pregnancy hormone).
- LMP: Last Menstrual Period — the first day of the last bleed, used to date cycles (this is considered cycle day 1).
- MC: Miscarriage — pregnancy loss before 20 weeks.
- OI: Ovulation Induction — medication to stimulate egg release.
- OPK: Ovulation Predictor Kit — urine test that detects the LH surge before ovulation.
- POAS: “Pee on a stick” — slang for taking a pregnancy test.
- RE: Reproductive Endocrinologist — fertility specialist doctor (although this term is used more in the US).
- SMEP: Sperm Meets Egg Plan — timed sex plan to increase chances of conception (typically cycle days 8, 10, 12, then three days in a row from the day of LH surge).
- TTC: Trying to Conceive.
- TWW/2WW: Two-Week Wait — the time between ovulation/embryo transfer and a pregnancy test.
Your NHS Eligibility
Use our NHS IVF Eligibility Calculator to discover if you can access free fertility treatment.
Tests and diagnostics
Tests and diagnostics can reveal what’s happening behind the scenes of your fertility, from hormone levels to the health of your uterus and sperm. Here, we briefly explain the most common checks, so you know what each one looks for and why it matters.
- Abdominal ultrasound: A scan across the abdomen that uses sound waves to check the uterus, ovaries, and early pregnancy.
- Antral Follicle Count (AFC): An ultrasound check of how many small egg-containing follicles are on the ovaries, often part of a standard Fertility MOT.
- Albumin levels: A blood test measuring a key protein that can reflect overall health and fertility.
- ALICE test (Analysis of Infectious Chronic Endometritis): A test that looks for harmful bacteria in the uterus linked to miscarriage and implantation problems.
- Anti-Müllerian Hormone (AMH): A blood test that gives an estimate of ovarian reserve (how many eggs remain), part of a standard Fertility MOT.
- Andrology: The medical field focused on male reproductive health and sperm.
- Chromosomal microarray: A detailed genetic test that can find chromosome issues sometimes linked to miscarriage.
- Cycle monitoring: Regular blood tests and scans to track ovulation and hormone changes during the menstrual cycle.
- Dehydroepiandrosterone sulphate test (DHEAS): A hormone test that helps assess ovarian function and conditions like PCOS.
- DNA fragmentation test: A sperm test that checks whether the DNA inside sperm is damaged, which can affect fertility.
- EMMA test (Endometrial Microbiome Metagenomic Analysis): A test that looks at the balance of bacteria in the uterus lining, which can affect implantation.
- Endometrial biopsy: A small tissue sample taken from the uterus lining to check health or investigate fertility issues.
- ERA test (Endometrial Receptivity Analysis): A test that can pinpoint the best time for embryo transfer by studying the uterus lining.
- Ejaculate volume: Part of semen analysis that measures how much fluid is released.
- Fertility MOT: A set of tests and scans (for men and women) that provide an overview of fertility health.
- Fertiloscopy: A minimally invasive procedure using a tiny camera to examine reproductive organs.
- Follicular phase monitoring: Tracking the first half of the cycle to see how eggs develop before ovulation.
- FSH (Follicle Stimulating Hormone): A hormone that helps eggs mature and is checked by blood test for fertility insights.
- Genetic compatibility testing: A test to see if both partners carry genetic conditions that could affect children.
- Genetic testing: Analysing DNA to spot inherited conditions or risks linked to infertility or miscarriage.
- hCG: Human Chorionic Gonadotropin – pregnancy hormone made after implantation, the hormone that pregnancy tests detect.
- HyCoSy: An ultrasound with contrast fluid to check if fallopian tubes are open.
- Hysterosalpingogram (HSG): An X-ray with dye to show if the uterus and fallopian tubes are clear.
- Hysteroscopy: A procedure using a small camera inserted through the cervix to look inside the uterus.
- Karyotyping: A genetic test that maps chromosomes to find abnormalities that may affect fertility.
- Kleihauer test: A blood test sometimes used in pregnancy complications to detect fetal blood cells in the mother’s blood.
- Laparoscopy: Keyhole surgery using a camera to look at the pelvic organs, often used to diagnose endometriosis.
- Micro-TESE: Microsurgical sperm retrieval from testicular tissue.
- Müllerian anomalies: An umbrella term for congenital uterine abnormalities (such as bicornuate uterus), which are typically diagnosed via ultrasound.
- Oligozoospermia: The clinical term for low sperm count.
- Ovarian reserve test: A blood test (often AMH or FSH) that gives an idea of how many eggs you may have left in your ovaries, sometimes paired with an AFC ultrasound scan.
- PGT-A: Preimplantation Genetic Testing for Aneuploidy — checks embryos for abnormal chromosome numbers.
- PGT-M: Preimplantation Genetic Testing for Monogenic disorders — screens embryos for specific inherited conditions.
- Prolactin: A hormone linked to milk production; high levels can disrupt ovulation.
- Protocol (treatment plan diagnostic): The specific plan of medications and timings used during fertility treatment.
- Pre-implantation tissue typing (PTT): A genetic test to help match embryos for compatibility in certain medical cases.
- Reproductive immunology: A specialist area looking at immune causes of infertility.
- Reproductive tract infection tests: Tests that check for infections that could affect fertility or pregnancy.
- Reactive Oxygen Species test (ROS): A sperm test checking oxidative stress that can damage DNA.
- Sperm Chromatin Structure Assay (SCSA): Sperm DNA integrity test.
- Semen analysis: A lab test that looks at sperm count, movement, shape, and volume.
- SHBG test: A blood test measuring sex hormone-binding globulin, which affects hormone balance.
- Sonohysterogram: An ultrasound with fluid added into the uterus to check its shape and lining.
- Sperm count: The number of sperm in a semen sample.
- Sperm morphology: How sperm are shaped, which can affect fertilisation.
- Sperm motility: How well sperm move, which helps them reach the egg.
- Sperm volume: The amount of semen produced in one sample.
- SRY gene: A gene on the Y chromosome that determines male sex development.
- T4 blood test: Measures thyroxine, a thyroid hormone that affects metabolism and fertility.
- Teratozoospermia: When many sperm are abnormally shaped, which may reduce fertility.
- Thyroid blood tests (TSH, Triiodothyronine, T4): Tests that measure thyroid function, which can affect cycles and fertility.
- Transvaginal hydropelviscopy (TVHL): A minimally invasive procedure to look at the pelvis and reproductive organs through the vagina.
- Transvaginal ultrasound: An internal scan, using a probe inserted into the vagina to check the uterus and ovaries in detail.
- Triiodothyronine blood test: Measures T3, a thyroid hormone important for metabolism and fertility health.
- TSH blood test: Measures thyroid-stimulating hormone, which controls how the thyroid works.
Treatments, procedures, and medications
From simple prescriptions to advanced lab techniques, fertility treatment can take many different forms. Here you’ll find clear explanations of the medications and procedures you’re most likely to encounter along the way.
- ART: Assisted Reproductive Technology (i.e. fertility treatments like IVF, IUI, and ICSI).
- Artificial insemination: Placing sperm directly into the reproductive tract to help with conception.
- Assisted hatching: A lab technique where the outer shell of an embryo is gently thinned to aid implantation.
- Buserelin: A medication used in IVF to help control hormone levels before stimulation.
- Chemical menopause (induced via medication): Temporary menopause created by drugs to manage conditions like endometriosis.
- Cleavage embryo transfer: Transferring an embryo into the uterus just a few days after fertilisation.
- Clomid: A pill that stimulates the ovaries to release eggs.
- Corpus luteum support (e.g. progesterone supplementation): Medication that helps the uterus lining stay ready for implantation.
- Cryopreservation: The freezing of eggs, sperm, or embryos for future use.
- Cyclogest: A form of progesterone given as pessaries or suppositories to support early pregnancy.
- D&C (Dilation and Curettage): A short procedure to clear the uterus after miscarriage or to investigate problems.
- Dexamethasone: A steroid sometimes used to manage hormone imbalances in fertility care.
- Donor conception: Using donated eggs, sperm, or embryos to conceive.
- Donor insemination (DI): Using donor sperm placed into the uterus to try to achieve pregnancy.
- Egg donor: A person who donates eggs for someone else’s fertility treatment.
- Egg freeze and share: A scheme where some eggs are frozen for yourself and some donated to others.
- Egg freezing: Collecting and freezing eggs for use in the future.
- Egg retrieval: The procedure where eggs are collected from the ovaries, usually during IVF.
- Embryologist: A specialist who cares for eggs, sperm, and embryos in the lab.
- Embryo adoption: Using embryos donated by another family after their own fertility treatment.
- Embryo biopsy: Taking a few cells from an embryo to carry out genetic testing.
- Embryo donor: Someone who donates embryos for another person or couple to use.
- Embryo freezing: Storing embryos at very low temperatures to use later.
- Embryo grading: Assessing embryos under a microscope to see which look healthiest.
- Embryo transfer: Placing an embryo into the uterus during IVF treatment.
- Endometrial scratch: A procedure that makes a small scratch in the uterus lining, thought to help implantation.
- Femara: A pill (also called letrozole) used to encourage ovulation.
- Fertility preservation: Freezing eggs, sperm, or embryos to protect future fertility.
- FIV: IVF in Spanish (Fecundación in Vitro) — useful to know if you’ve chosen to carry out your IVF abroad.
- Freeze-all cycle: A treatment where all embryos are frozen for transfer in a later cycle.
- Fresh embryo transfer: Transferring an embryo a few days after it’s created, in the same cycle.
- Frozen embryo transfer: Thawing and transferring an embryo from an earlier cycle.
- GnRH agonists / antagonists: Medicines that control hormone release to regulate IVF cycles.
- Gonadotrophins: Injectable hormones that stimulate the ovaries to produce eggs.
- Home insemination: Placing sperm into the vagina at home to try for pregnancy.
- ICI: Intracervical insemination — sperm placed at the cervix.
- ICSI: Intracytoplasmic Sperm Injection — a lab procedure where a single sperm is injected into an egg.
- Intralipid infusion: A treatment given through a drip that may help with immune-related fertility issues.
- IUI: Intrauterine Insemination — placing sperm directly into the uterus.
- IVF: In Vitro Fertilisation — eggs and sperm combined in a lab to create embryos.
- Letrozole: Another name for Femara, a medicine that can trigger ovulation.
- Mini/mild IVF: A lower-dose version of IVF using fewer stimulation drugs.
- Oncofertility: Preserving fertility (like freezing eggs, sperm, or embryos) before cancer treatment.
- Ovulation induction (OI): Medicines that help trigger egg release in people who don’t ovulate regularly.
- Ovarian stimulation: Using medication to make the ovaries develop multiple eggs at once.
- Ovarian tissue freezing: Freezing a piece of ovary that contains eggs, usually for medical reasons.
- PESA or TESA: Surgical procedures to collect sperm directly from the testicles or epididymis.
- Polymenorrhea: Having menstrual cycles that are unusually short (typically less than 21 days).
- PRP (Platelet-Rich Plasma treatment): A treatment using your own blood plasma to try to improve the uterus lining or ovaries.
- Reciprocal IVF: One partner’s eggs are used, and the other partner carries the pregnancy.
- Shoebox IVF: A lower-cost, simplified IVF option offered at some clinics.
- Slow freezing: An older method of freezing eggs or embryos, now less common than vitrification.
- Social egg freezing: Freezing eggs for non-medical reasons, such as delaying pregnancy.
- Sperm donor: A person who donates sperm for someone else’s fertility treatment.
- Sperm freezing: Collecting and storing sperm so it can be used for future fertility treatment.
- Sperm washing: A lab process that separates healthy sperm for use in IUI or IVF.
- Surgical sperm extraction: Retrieving sperm directly from the testicles or surrounding tissue.
- Surrogacy: Another person carries and gives birth to a baby for you.
- Testicular tissue freezing: Storing small pieces of testicular tissue that contain sperm.
- Treatment add-ons: Extra procedures or medicines offered alongside standard IVF.
- Third party reproduction: Any fertility treatment involving a donor or surrogate.
- Three-parent IVF: A technique that uses DNA from three people to avoid passing on mitochondrial disease.
- Tubal litigation: A permanent procedure that blocks or cuts the fallopian tubes.
- Utrogestan: A type of progesterone used to support early pregnancy.
- Vasectomy: A surgical procedure that blocks sperm release and prevents pregnancy.
- Vitrification: A rapid freezing method that helps protect eggs and embryos.
- Zomacton: A growth hormone sometimes used in fertility treatment to improve egg quality.
Find the right fertility clinic for you
Choosing a fertility clinic is a big decision — and we’ve made it clearer.
Conditions and complications
Fertility isn’t always straightforward, and sometimes underlying conditions or unexpected complications play a role. Here are some explanations of the issues that can arise, and how they may affect the path to pregnancy.
- Adenomyosis: A condition where tissue like the uterus lining grows into the muscle wall, sometimes causing pain and heavy periods.
- Aneuploidy: When an embryo has too many or too few chromosomes, which can affect development.
- Anovulation: When the ovaries don’t release an egg during a cycle.
- Antisperm antibodies: An immune reaction where the body attacks sperm, making fertilisation harder.
- Arcuate uterus: A uterus with a slight dip at the top, usually not affecting fertility.
- Azoospermia: When no sperm are found in the semen.
- Balanced translocation: A genetic change where pieces of chromosomes swap places, sometimes linked to miscarriage or infertility.
- Bicornuate uterus: A uterus shaped with two “horns” or sections, which can raise pregnancy risks.
- Blighted ovum: A pregnancy sac develops, but no embryo forms.
- Chemical pregnancy or biochemical pregnancy: Very early pregnancy loss after a positive test but before an ultrasound heartbeat.
- Diminished ovarian reserve: Lower egg supply than expected for age.
- Ectopic pregnancy: When a pregnancy implants outside the uterus, often in a fallopian tube.
- Empty follicle syndrome: No eggs are collected during egg retrieval, despite follicles growing.
- Endometriosis: A condition where tissue like the uterus lining grows outside the womb, often causing pain and fertility issues.
- Failed implantation: When an embryo doesn’t attach to the uterus lining.
- Fallopian tube blockage: Tubes are blocked or damaged, stopping eggs and sperm from meeting.
- Fibroids: Non-cancerous growths in or around the uterus that may affect fertility or pregnancy.
- Hashimoto’s disease (thyroiditis): An autoimmune condition that can cause an underactive thyroid.
- Hydatidiform mole (molar pregnancy): A rare complication where abnormal cells grow in the uterus instead of a healthy pregnancy.
- Hydrosalpinx: A blocked fallopian tube filled with fluid, which can make it harder to get pregnant.
- Hyperovulation: When the ovaries release more than one egg in a cycle.
- Hyperthyroidism: An overactive thyroid that can affect cycles and fertility.
- Hypothalamic amenorrhea: When periods stop due to low hormone signals from the brain.
- Hypothyroidism: When the thyroid gland is underactive and doesn’t make enough hormones, which can affect periods, ovulation, and fertility.
- Implantation failure: When embryos repeatedly don’t attach to the uterus lining after transfer.
- Incomplete miscarriage: When some pregnancy tissue remains in the uterus after a miscarriage.
- Infertility: Not conceiving after 12+ months of trying (6+ months if over 35).
- Kartagener’s Syndrome: A rare condition affecting cilia (tiny cell hairs), linked to male infertility.
- Male infertility (male factor infertility): Fertility problems caused by issues with sperm count, shape, or movement.
- Menopause: When periods stop permanently, marking the end of fertility.
- Miscarriage: Pregnancy loss before 24 weeks.
- Missed miscarriage: The embryo stops developing but there are no immediate miscarriage symptoms.
- Mitochondrial donation: A technique using healthy mitochondria from a donor egg to avoid inherited disease.
- Molar pregnancy: A rare condition where abnormal cells grow instead of a healthy pregnancy.
- Necrospermia: When most sperm in semen are not alive.
- Ovarian Hyperstimulation Syndrome (OHSS): A reaction to fertility drugs causing swollen, painful ovaries.
- Ovarian remnant syndrome: Small ovarian tissue left behind after surgery, sometimes causing pain or cysts.
- Polycystic ovaries (PCO): Ovaries showing many small follicles on ultrasound, not always the same as PCOS.
- Polycystic Ovary Syndrome (PCOS): A hormone condition affecting ovulation, periods, and fertility.
- Perimenopause: The years leading up to menopause when cycles and hormones change.
- Pelvic Inflammatory Disease (PID): Infection of the reproductive organs that can cause scarring and fertility issues.
- Posthumous conception: Conception using sperm, eggs, or embryos after a partner has died.
- Premature ovarian failure: When the ovaries stop working before age 40 (also called premature ovarian insufficiency).
- Primary infertility: Never having conceived after a year of trying.
- Recurrent miscarriage: Two or more miscarriages in a row.
- Retained products of conception (RPOC): Tissue from a pregnancy left behind in the uterus after miscarriage or birth.
- Retrograde ejaculation: When semen enters the bladder instead of leaving through the penis.
- Secondary infertility: Struggling to conceive again after already having a child.
- Septate uterus: A uterus divided by a band of tissue, which can affect pregnancy.
- Silent endometriosis: Endometriosis without obvious symptoms.
- Social infertility: When someone can’t conceive without help due to their circumstances (e.g. same-sex couples, single parents by choice).
- Subfertility: Reduced fertility that makes conceiving slower or harder but not impossible.
- Teratoma: A type of ovarian tumour, sometimes found during fertility investigations.
- Tubal factor infertility: Infertility caused by blocked or damaged fallopian tubes.
- Unexplained infertility: Infertility with no clear cause found after testing.
- Unicornuate uterus: A uterus that only developed on one side, shaped like half a uterus.
- Vaginal blockage: When the vagina is blocked by tissue or scarring, affecting sex or fertility.
- Varicocele: Enlarged veins in the scrotum that can lower sperm quality.
- Zona hardening: Changes to the outer shell of the egg/embryo that may affect fertilisation.
Anatomy and biology
Knowing how your body works at a biological level can bring clarity when you’re trying to conceive. Here you’ll find the key organs, cells, and processes that play a role in fertility, in simple terms.
- Blastocyst: An embryo about five days after fertilisation, ready to implant in the uterus.
- Cervical mucus: The fluid made by the cervix that changes through the cycle to help (or block) sperm.
- Chromosome (X and Y): Packages of DNA that carry genetic information and determine biological sex.
- Corpus luteum: A temporary structure formed after ovulation that makes progesterone to support early pregnancy.
- Embryo: A fertilised egg that has started dividing into cells.
- Endometrium: The lining of the uterus that thickens each month to prepare for implantation.
- Fallopian tubes: The tubes that carry eggs from the ovaries to the uterus, and where fertilisation usually happens.
- Fertile window: The days in a cycle when sex is most likely to lead to pregnancy.
- Follicle: A small fluid-filled sac in the ovary where an egg develops.
- Follicular phase: The first half of the cycle, when eggs grow and the uterus lining thickens.
- Gametes: Reproductive cells — eggs in women and sperm in men.
- Hormones: Chemical messengers that control cycles, ovulation, and fertility.
- Implantation: When an embryo attaches to the uterus lining to start a pregnancy.
- Leydig cells: Cells in the testes that make testosterone.
- Luteal phase: The second half of the cycle after ovulation, when the uterus lining is prepared for implantation.
- Luteal phase defect: When the luteal phase is too short or hormone levels too low to support implantation.
- Luteinising Hormone (LH): The hormone that triggers ovulation mid-cycle — people typically see a rise or peak in LH 24-48 hours before ovulation.
- Menstrual cycle: The monthly hormonal cycle that prepares the body for pregnancy.
- Mitochondria: The “powerhouse” of cells, giving eggs and sperm the energy they need.
- Oestrogen: A key hormone that regulates cycles and supports egg growth and uterus lining development.
- Ovary: The organ that stores eggs and produces hormones.
- Ovulation: The release of a mature egg from the ovary.
- Period: The bleeding that happens when pregnancy doesn’t occur and the uterus lining sheds.
- Semen: The fluid that carries sperm out of the body.
- Sertoli cells: Cells in the testes that help sperm develop.
- Sperm: Male reproductive cells that fertilise the egg.
- Testicles: The organs that make sperm and testosterone.
- Testosterone: The main male sex hormone, also important for sperm production.
- Uterus: The organ where a pregnancy develops.
- Vagina: The canal leading from the cervix to the outside of the body.
- Vulva: The external female genitals.
- Womb: Another word for uterus.
- Zona pellucida: The protective shell around an egg and early embryo.
- Zygote: The very first stage after an egg and sperm join together.