Aneuploidy: the loss or gain of one or more chromosomes
Assisted Reproduction Technology (ART): all treatments that include in vitro handling of human gametes (eggs and sperm) and embryos to establish a pregnancy – often called MAR (Medically Assisted Reproduction)
Blastocyst: 5-6 days old embryo
Clinical pregnancy: a pregnancy diagnosed by ultrasound of by definite signs of pregnancy
Clone: a copy of a (DNA) molecule, a (stem) cell or an individual. Cloning of an individual is done by replacing the nucleus of an egg cell with the genetic material from a somatic (non-germ) cell. Cloning can also be done to produce stem cells, the undifferentiated early cells from which all types of cells develop. This technique may in future enable people to access life-saving treatments tailored-made from their own DNA.
Cryopreservation: frozen storage of sperm, eggs, embryos or ovarian and testicular tissues
Delivery rate: number of deliveries per 100 cycles (aspiration or embryo transfer cycles)
Ectopic pregnancy: implantation of the embryo outside the uterus
Embryo: the product up to eight weeks after fertilisation, later it is called a foetus
Embryo donation: transfer of an embryo that did not originate from the recipient and her partner
Endometriosis: condition where endometrial tissue grows in areas other than the uterine cavity
FER: frozen embryo replacement
Fertilisation: a sperm penetrates the egg leading to a combination of genetic material resulting in a fertilised egg
Follicle: a fluid filled sac that contains an immature egg. Located in the ovaries, follicles develop each cycle, one ovulates into an egg.
Gamete: a reproductive cell, egg in females and sperm in males
Gamete intra-fallopian transfer (GIFT): process by which eggs and sperm are introduced in the Fallopian tube.
Infertility: a disease of the reproductive system defined by the failure to conceive after 12 months of regular unprotected sexual intercourse
Intracytoplasmic sperm injection (ICSI): process by which an egg is fertilised by injecting a single sperm into the egg
Intrauterine Insemination (IUI): the insemination of washed semen directly into the uterus
In vitro fertilisation (IVF): fertilisation of an egg by sperm in a laboratory dish
Micro-epididymal sperm aspiration (MESA): surgical collection of sperm direct from the epididymis (tube that carries sperm out of the testis). Used when a blockage in the epididymis leads to absence of sperm in the semen.
Miscarriage / preclinical spontaneous abortion: pregnancy diagnosed by the detection of HCG in serum or urine that does not develop into a clinical pregnancy
Percutaneous epididymal sperm aspiration (PESA): collection of sperm under local anaesthesia by needle aspiration of the epididymis.
Polycystic Ovarian Syndrome (PCOS): a condition characterised by irregular or absent menstruation, acne, obesity and excess hair growth
Pre-implantation genetic diagnosis (PGD): diagnostic technique involving genetic tests on an embryo or a polar body (a cell structure inside the egg). Usually done when the embryo is at the 6-8 cell stage. One cell is removed for analysis of its DNA or chromosomes to determine if the embryo is likely to develop a genetic disease.
Pre-implantation genetic screening (PGS): technique to check if an embryo has the correct number of chromosomes. Used particularly for older women (at increased risk of chromosomal abnormalities) and for women who have had recurrent miscarriages (often due to chromosomal abnormalities). It is still in the experimental phase, since it is not yet evidence based.
Single Embryo Transfer (SET): method of selecting one embryo for transfer to lower the risk of multiple pregnancies.
Stillbirth / Fetal death: death of a foetus before it is born at or after 20 weeks of pregnancy
Testicular sperm aspiration (TESA): needle aspiration of the testis to collect sperm, usually carried out in cases where PESA has been unsuccessful.
Testicular sperm extraction (TESE): done when other extraction methods were unsuccessful
Vitrification: an ultra-rapid freezing method for eggs and embryos. It avoids the damage usually caused in freezing from ice crystals.
EU documents archive (for members only)
ESHRE Position Papers