Understanding fertility language

Most areas of medicine and science have their own jargon and fertility is no exception. The most common terms are listed here. 

& Letrozole













































Day 1






A pill usually taken for 5 days early in the menstrual cycle that increases the number of follicles that grow in the ovary. Commonly used in Ovulation Induction.

Ovulation Induction is a treatment to induce ovulation in women with irregular or absent cycles.

Intra-Uterine-Insemination is when sperm is placed directly into the uterus

In Vitro Fertilisation. It strictly means adding sperm and egg together outside the body, but it is usually used to describe the whole process covering medications, egg collection, fertilisation, and embryo transfer.

Intra-Cytoplasmic Sperm Injection. Surely one of the craziest bits of IVF jargon – it simply means a single sperm is injected into each egg when the sperm cannot do this job themselves.

Intra-cytoplasmic Morphologically selected Sperm Injection. An even worse bit of jargon describing ultra-high magnification of sperm before they are selected for ICSI.

In Vitro Maturation is a variation of IVF that starts with immature eggs collected without using ovarian stimulation.


Donor Sperm (formerly called Donor Insemination). Donor sperm can be used with IUI and IVF.

Donor Oocyte or donor egg – ‘oocyte’ is the scientific name for an egg. Donor egg is when another woman’s egg is used in an IVF cycle.

Donor embryo is when an embryo is donated to someone who is not the
biological parent.

IVF treatment terminology

One course of treatment. With IVF, this is from Day 1 through to the pregnancy test.

Oocyte PickUp – also known as egg collection, when the eggs are taken from
the ovaries.

Embryo Transfer – when the embryo(s) is transferred back into the uterus.
SET Single Embryo Transfer – when only one embryo is transferred into the
uterus at a time.

Frozen Embryo Transfer. Essentially the defrosting and replacement of an embryo that has been frozen and stored with us after a cycle of ivf . Also known as Thawed Embryo Replacement (TER).

An artificial menstrual cycle used to provide the right environment for the transfer of embryos.

The name given to an embryo 5-6 days after fertilisation when it consists of an outer layer of cells that will become the placenta and an inner mass of cells that will become the baby.

Surgical Sperm Retrieval – when sperm are taken directly from the testes using a fine needle.

Percutaneous Epididymal Sperm Aspiration – SSR when sperm are taken from the epididymis, which is a tiny organ sitting on top of the testis.

Testicular Sperm Aspiration, Testicular Sperm Extraction – other names for SSR.

Ovarian Hyper-Stimulation Syndrome – a condition that can occur a few days after egg collection that is caused by too many follicles being stimulated to grow at once in the ovaries. Fluid moves from the blood into the abdomen and into tissue. Untreated, it can have serious consequences.

Pre Implantation Genetic Diagnosis, which is testing embryos for a genetic condition.

Pre Implantation Genetic Screening, which is testing embryos to see if they have the correct number of chromosomes.


Timelapse Morphometry Imaging, for studying embryo development.

The first day of your period or menstrual bleeding. When you start a treatment
cycle, we count day 1 as the first day you wake with your period. So if your period starts in the afternoon, the next day is called day 1.

This is a fine tube put into the body. In fertility it nearly always refers to a catheter put into the uterus for embryo transfer in IVF or insemination in IUI.

A pregnancy that ends at a very early stage. Its name comes from the fact that the pregnancy is detected by biochemical tests like blood tests.


A pregnancy that can be detected by an ultrasound scan.






Amniotic membrane





Basal body

Body Mass Index (BMI)







Chorionic membrane

Chorionic Villus
Sampling (CVS)




Conjoined twins


Corpus luteum


Dilatation and
curettage (D&C)

Ectopic pregnancy






Fallopian tube





Follicular phase



Granulosa cells

Human chorionic gonadotrophin (hCG)






Luteal phase

Luteinising hormone (LH)


Menstruation period



Ovarian stimulation




Pelvic inflammatory disease

Peri menopause

Phyto oestrogens


Pituitary gland








Semen analysis

Seminal fluid

Siamese twins

Spermatogenesis & Spermatogonia


Spina bifida





Zona pellucida

Other terminology you may come across

The area of the tummy

The membrane covering the head of the sperm containing the enzymes that are released to enable the sperm to enter the egg.

Procedure where cells are taken from the fluid around the foetus to detect abnormalities, usually between the 15th and 17th weeks of pregnancy

Inner membrane around the amniotic fluid containing a foetus

Severe neural tube defect in which there is no brain development


Lack of ovulation

Absence of sperm in the semen

Ovulation leads to increased blood progesterone levels which are associated with a small rise in body temperature.

Measure of body mass determined by dividing a person's weight (in kilograms) by height (in metres) squared. Normal values are between 20 and 25.

The final phase of development in the sperm in which it acquires the ability to fertilise an egg


The lower narrow end of the uterus that connects the uterine cavity to the vagina.

Infection that may damage the reproductive system.

The outer layer of the membranes that surround the foetal sac

A procedure where cells are taken from the placenta around 11 weeks of pregnancy to test for abnormalities in the foetus.

Structures in the cell nucleus that contain our hereditary material in the form of DNA

                                                                                                                                                          Hair-like projections that line some tubes, e.g., the Fallopian tubes

Twins that are joined by some parts of their bodies.


A yellow structure in the ovary formed after the rupture of the egg from that site. It produces progesterone.

Undescended testes

Operation to scrape out the lining of the uterus 

Pregnancy outside the uterus, commonly in the Fallopian tube.

The discharge of semen from the penis during male orgasm

The presence of endometrial cells at sites outside the lining of the uterus

Lining of the uterus

A coiled tube 3-5 m in length attached to the back of the testis. It stores sperm and gives rise to their motility.

Tube that runs from the uterus out towards the ovary. It is responsible for the passage of sperm, eggs and embryos.

The probability of a live birth from one cycle of ovulation

Benign muscular growth in the uterus

Delicate, finger-like fringes that collect the egg

A fluid-filled sac in the ovary in which the egg matures

The phase of the menstrual cycle in which the dominant follicle grows to reach maturity. The follicular phase is completed at the time of egg release (ovulation)
Length of pregnancy

Cells that surround each egg and line each follicle and are responsible for feeding the egg with nutrients and producing oestrogen

Hormone that is produced by the developing placenta


Placing sperm into the cervix or uterus, or in IVF placing sperm with the eggs in culture conditions the laboratory

A test looking at the number and appearance of chromosomes from cells

Technique in which a telescope visualises the structures within the abdomen. Commonly used to check tubal patency and the presence of any pelvic pathology

Last menstrual period

The phase of the menstrual cycle from ovulation to the start of the next period

One of the hormones produced by the pituitary gland in the brain. A rapid rise of LH initiates the onset of ovulation

Onset of menstruation

The lining of the uterus is shed in response to falling oestrogen and progesterone levels at the end of the luteal phase

A hormone produced by the ovaries

Stimulating the ovary to produce more than one mature egg in a menstrual cycle by giving fertility drugs

The female gonad that contains the eggs

Release of the egg from the ovary. This usually occurs about 14 days before the next menstrual period

The egg

Infection of the tubes and uterus that can lead to infertility by adhesion formation

The five to 10 years prior to cessation of periods (menopause)

Oestrogens in plants

Pituitary gland A small gland at the base of the brain. It produces FSH, LH and other hormones

The organ that transfers nutrients and oxygen from the mother to the baby

Hormone produced by the corpus luteum. It prepares the uterus for implantation of a developing embryo if fertilisation has occurred

Once an egg has been fertilised, two pronuclei may be seen, one from the egg and one from the sperm

The time in adolescence in which sexual organs mature and secondary sexual characteristics appear
The pouch that contains the testicles

Fluid that constitutes the ejaculate

The microscopic examination of semen to determine the number of sperm (sperm count) their shapes (morphology) and their ability to move (motility) The liquid part of the semen in which sperm swim around

Conjoined twins

Sperm production   & The cells within the testis that differentiate into sperm

The male reproductive cell that unites with the egg (ovum) to produce an embryo

A developmental abnormality in which the bones of the spinal column do not fuse
The male gonads responsible for production of sperm and testosterone

High frequency sound waves that may be used to identify bodily structures

The organ in the female in which the foetus develops. Often called the womb

The canal in the female that leads to the cervix, which leads to the uterus

Outer covering or ”shell' of the egg