ACU - Assisted Conception Unit.
Anovulation - When an egg is not released from the ovary, each cycle.
ART - Assisted Reproductive Technology. Conception which involves the use of medical technology, e.g. IVF and PGD.
Azoospermia - The complete absence of sperm in the male ejaculate.
Blastocyst - An embryo that has developed for five to six days after fertilisation.
BMI - Body Mass Index – your weight (in kg) divided by your height (in square metres).
Cervix - The narrow passage at the lower end of a woman's uterus, connecting to her vagina.
Chromosome - A threadlike structure of DNA containing genes, which carries genetic information.
Downregulation - Part of infertility treatment, using medication, which make a woman's ovaries temporarily inactive to prevent the release of eggs before they are collected.
DI - Donor insemination. The introduction of donor sperm into the uterus.
DNA - Di-ribonucleic acid basic formation of genetic code.
Ectopic pregnancy - A pregnancy, which implants outside the uterus.
Egg - Gamete produced by a woman during her monthly cycle.
Embryo - A fertilised egg.
Endometrium - The lining of the uterus, which grows and sheds during a normal menstrual cycle and which supports a pregnancy.
Endometriosis - A female condition in which endometrial cells, which normally line the uterus, implant around the outside of the uterus and/or ovaries, causing pain, internal bleeding and reduced fertility.
Epididymis - The area above a man's testicle where sperm are stored.
Fallopian tubes - The tubes on either side of the uterus where the sperm should fertilise the egg and the embryo should travel through to the uterus.
Fertilisation - The penetration of an egg by a sperm resulting in the formation of an embryo.
Fibroids - Benign (non-cancerous) overgrowth of the muscle layer of the womb. Can be linked with fertility problems if the fibroids grow into the lining of the womb or are very large.
Follicle - A collection of fluid within the ovary, which usually contains an egg if it grows to a certain size.
FSH - Follicle Stimulating Hormone. The hormone produced by the brain to stimulate the ovary to make one or more follicles grow. Is available in synthetic form to use in fertility treatment.
Gametes - Eggs or sperm.
HCG - Human Chorionic Gonadotrophin. An injection given to a woman having IVF to mature the eggs. Also indicates pregnancy.
HFEA - Human Fertilisation and Embryology Authority. A Government body which regulates clinics performing IVF and other treatments using sperm, eggs and embryos.
ICSI - Intracytoplasmic Sperm Injection. When a single sperm is injected into a single egg.
IVF - In Vitro Fertilisation. Eggs and sperm are mixed together in a laboratory dish to achieve fertilisation. Any fertilised eggs are then placed inside the uterus.
In vivo - In the body.
In vitro - In a laboratory setting.
Multiple pregnancy - Two or more babies.
Oestrogen - Female sex hormone produced by the ovary. Levels change throughout the cycle.
Oocyte/Ovum - The female gamete (egg).
Ovary - The female reproductive organ, which produces egg(s) from hormone stimulated follicles.
OHSS - Ovarian Hyper Stimulation Syndrome. Can occur if there are a large number of follicles/eggs, causing abdominal bloating, pain, nausea and breathlessness.
PCOS - Polycystic Ovarian Syndrome. A condition where multiple, small follicles arrange themselves around the outside of the ovary. Can be an isolated ultrasound finding but also associated with hormone imbalances and irregular ovulation. Made worse by excess weight.
PESA - Percutaneous Epididymal Sperm Aspiration. A fine needle is passed into the epididymis, under local anaesthetic and sedation to find sperm in men where there is a blockage between production in the testicle and appearance in the ejaculate.
PGD - Preimplantation Genetic Diagnosis. The removal of one or two cells from an embryo to test for genetic diseases. Only unaffected embryos are transferred.
Semen - Ejaculated sperm.
Sperm - Male gametes.
Stem cells - Cells which have the potential to grow into different types of cells in the body.
TESA - Testicular Sperm Aspiration. A sperm extraction technique, which involves inserting a needle into a man's testicle to remove testicular tissue.
TESE - Testicular Sperm Extraction. A sperm extraction technique, which involves making a small cut in a man's scrotum and the removal of a small amount of testicular tissue.
Uterus - A female organ, also known as the womb.
Zona Pellucida - The outer coating of the egg. Embryos/fertilised eggs have to 'hatch' out of this before they can implant.