Fertility glossary

AMH

Anti-Müllerian hormone. A blood test reflecting how many eggs remain — egg quantity, not egg quality. It predicts how you will respond to stimulation medicines, but it is a poor predictor of natural conception.

Andrology

The branch of medicine dealing with male reproductive health.

Antral follicle count (AFC)

An ultrasound count of the small resting follicles in both ovaries, used alongside AMH to assess ovarian reserve.

ART

Assisted Reproductive Technology — the umbrella term for treatments where eggs or embryos are handled outside the body, including IVF and ICSI.

Assisted hatching

Thinning the outer shell of an embryo before transfer. Used selectively; not beneficial for everyone.

Azoospermia

No sperm in the ejaculate. It may be obstructive (production is fine, the passage is blocked) or non-obstructive. Sperm can often still be retrieved surgically.

Beta hCG

The blood test that confirms pregnancy after treatment. More reliable than a home urine test, especially after a trigger injection.

Blastocyst

An embryo at about day five, by which point it has around a hundred cells and has separated into the part that becomes the baby and the part that becomes the placenta.

Cleavage stage

An embryo on day two or three, when it has divided into roughly two to eight cells.

Clomifene

A tablet used to induce ovulation. Letrozole is now often preferred, particularly in PCOS.

Cryopreservation

Freezing eggs, sperm or embryos for later use.

DFI

DNA Fragmentation Index — a measure of damage to the genetic material inside sperm, which a standard semen analysis does not detect.

Down-regulation

Temporarily switching off your natural hormone cycle so that stimulation can be controlled precisely.

Egg collection (OPU)

Retrieving eggs from the ovaries using ultrasound guidance, under sedation. Takes around twenty minutes.

Embryo transfer

Placing an embryo into the uterus through a fine catheter. Quick, and needs no anaesthetic.

Embryologist

The scientist who handles eggs, sperm and embryos in the laboratory, and who assesses how embryos are developing.

Endometriosis

Tissue similar to the uterine lining growing outside the uterus, causing pain and sometimes affecting fertility.

Endometrium

The lining of the uterus, which thickens through the cycle and is where an embryo implants.

FET

Frozen Embryo Transfer — transferring a previously frozen embryo in a later cycle. Costs far less than a full IVF cycle.

Fibroid

A benign muscular growth in the uterus. Whether it affects fertility depends mostly on its position, not simply its presence.

Follicle

The fluid-filled sac in the ovary containing a developing egg. Follicles are what monitoring scans measure.

FSH

Follicle Stimulating Hormone. Both a natural hormone and the basis of many stimulation medicines.

Gonadotropins

Injectable hormone medicines used to stimulate the ovaries. Usually the largest single cost variable in an IVF cycle.

HSG

Hysterosalpingogram — an X-ray with dye that checks whether the fallopian tubes are open.

Hysteroscopy

A camera examination of the inside of the uterus, which also allows treatment during the same procedure.

ICSI

Intracytoplasmic Sperm Injection — injecting a single sperm directly into an egg. Used for sperm problems or previous fertilisation failure. Not a better version of IVF.

IMSI

ICSI performed under much higher magnification to select the sperm. Used selectively.

Implantation

When an embryo embeds into the uterine lining. The step that cannot be observed and cannot be influenced by resting.

Insulin resistance

Reduced response to insulin, common in PCOS. It drives higher androgen levels and disturbs ovulation.

IUI

Intrauterine Insemination — placing prepared sperm directly into the uterus around ovulation. Requires at least one open fallopian tube.

IVF

In Vitro Fertilisation — eggs and sperm brought together in the laboratory, with the resulting embryo transferred to the uterus.

Letrozole

A tablet used for ovulation induction. Now generally preferred over clomifene in PCOS, having shown higher live birth rates in trials.

Live birth rate

The proportion of cycles resulting in a baby born. The figure that actually matters, and always lower than a quoted pregnancy rate.

Luteal phase

The second half of the cycle, after ovulation.

Morula

An embryo at around day four, a compacted ball of cells, between the cleavage stage and the blastocyst.

Motility

How well sperm move. Progressive motility — moving purposefully forward — matters more than movement alone.

Morphology

The shape of sperm. Assessed against strict criteria, so even fertile men have a low percentage of perfectly formed sperm.

Oligospermia

A lower than normal sperm concentration.

OHSS

Ovarian Hyperstimulation Syndrome — an excessive response to stimulation medicines. Mild forms are fairly common; severe OHSS is uncommon and largely preventable.

Ovarian reserve

The number of eggs remaining. Assessed with AMH and antral follicle count. It says little about egg quality, which is driven by age.

Ovulation induction

Using medicines to bring about ovulation in someone who is not ovulating reliably. Often all that is needed.

PCOS

Polycystic Ovary Syndrome — the most common cause of irregular ovulation, and among the most treatable causes of difficulty conceiving.

PCPNDT Act

The Indian law prohibiting prenatal sex determination and sex selection. It applies absolutely, and no clinic may perform these in any form.

PGT

Preimplantation Genetic Testing — testing embryos before transfer. Considered in specific situations, not a routine part of IVF, and never used for sex selection.

Progesterone

The hormone that prepares and maintains the uterine lining. Commonly given as support after embryo transfer — and it causes symptoms that mimic early pregnancy.

Semen analysis

The core test of male fertility, measuring volume, concentration, motility and morphology. Quick, inexpensive, and often left until far too late.

Single embryo transfer (SET)

Transferring one embryo rather than two. Usually the safer choice, because twin pregnancies carry materially higher risks.

Sperm retrieval (TESA/PESA/micro-TESE)

Surgical techniques for collecting sperm directly from the testis or epididymis where there is none in the ejaculate.

Stimulation

The phase of an IVF cycle where injections encourage several eggs to mature rather than the single egg of a natural cycle.

Trigger injection

The final injection that matures the eggs before collection. It contains hCG, which is why home pregnancy tests can mislead for up to two weeks afterwards.

Two-week wait

The interval between embryo transfer and the pregnancy test. Consistently reported as the hardest part of treatment.

Varicocele

Enlarged veins in the scrotum which can raise temperature and impair sperm production. Treatable where significant.

Vitrification

Ultra-rapid freezing that prevents ice crystals forming. The reason modern frozen transfers succeed at rates comparable to fresh.

Zygote

A fertilised egg, before it begins dividing.

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