Fertility & obstetrics glossary

The terms, hormones, tests, and procedures you'll hear during fertility treatment and pregnancy — each explained in plain language.

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AMH — Anti-Müllerian hormone — a blood marker of how many eggs remain in the ovaries (ovarian reserve). It reflects egg quantity, not egg quality.
Anovulation — A menstrual cycle in which no egg is released from the ovary. Bleeding can still occur, so an anovulatory cycle may look like a normal period from the outside.
Anti-TPO Antibodies — Immune proteins that target the thyroid's own peroxidase enzyme — a marker of autoimmune thyroid disease (commonly Hashimoto's thyroiditis), not a direct measure of thyroid function.

Blastocyst — An embryo at day 5–6 of development — the stage at which it naturally implants, and the preferred stage for transfer in many IVF cycles.

Egg retrieval — The IVF procedure where eggs are collected from the ovaries using a fine needle guided by ultrasound, done under short sedation. Also called ovum pick-up (OPU).
Embryo transfer — The final step of an IVF cycle — the embryo is placed into the uterus through a thin catheter. Quick, gentle, and done without anaesthesia.
Endometriosis — A condition where tissue similar to the uterine lining grows outside the uterus — causing painful periods and, in some women, difficulty conceiving.
Endometrium — The inner lining of the uterus — it thickens each cycle to receive an embryo, and sheds as the period if pregnancy doesn't occur.
Epidural — Numbing medicine given through a thin tube (catheter) in the lower back. It blocks labour pain while you stay fully awake and can still feel pressure and push.
Estradiol — The main form of estrogen during the reproductive years — made by growing follicles, it builds the uterine lining and is tracked closely during IVF monitoring.

Fertile window — The roughly six days in each cycle when pregnancy is possible — the five days before ovulation plus the day of ovulation itself.
Fertility preservation — Freezing eggs, sperm, or embryos to protect the option of pregnancy later — whether for medical reasons or personal timing.
FSH — Follicle-stimulating hormone — the hormone that tells the ovaries to grow follicles (the sacs that hold eggs) each cycle. A common blood test in fertility evaluation.

ICSI — Intracytoplasmic sperm injection — a single sperm is injected directly into each egg under a microscope. An add-on to IVF used mainly for male-factor infertility (sperm problems).
IUI — Intrauterine insemination — washed, concentrated sperm is placed directly into the uterus around the time of ovulation, so sperm have a shorter distance to travel to the egg.
IVF — In-vitro fertilization — eggs are collected from the ovaries and fertilized with sperm in the laboratory, and the resulting embryo is placed in the uterus.

LH — Luteinizing hormone — the hormone whose mid-cycle surge triggers ovulation, releasing the egg from its follicle. It's what home ovulation kits detect.

OHSS — Ovarian hyperstimulation syndrome — an over-response to fertility injections in which the ovaries swell and leak fluid into the abdomen, causing bloating, pain and, in severe cases, breathlessness.
Ovarian reserve — The number of eggs remaining in the ovaries. Measured with AMH, FSH, and an ultrasound follicle count — it reflects quantity, not quality.
Ovulation — The release of a mature egg from the ovary, once each menstrual cycle. Timing sex or fertility treatment for pregnancy is planned around it.

PCOS — Polycystic ovary syndrome (renamed Polyendocrine Metabolic Ovarian Syndrome, PMOS, in May 2026) — a common hormonal condition where ovulation becomes irregular. It is one of the most frequent, and most treatable, causes of infertility.
PGT — Preimplantation genetic testing — a small biopsy from a blastocyst is screened for chromosomal or genetic issues before it's chosen for transfer.
Progesterone — The hormone of the second half of the cycle — it prepares and maintains the uterine lining for implantation, and supports early pregnancy.
Prolactin — A hormone that drives breast-milk production and can suppress ovulation. Besides breastfeeding, it can be raised by stress, some medicines, thyroid problems, or a benign pituitary growth, most often noticed first as a changed period rather than nipple discharge.

Recurrent implantation failure — When good-quality embryos repeatedly fail to implant across multiple IVF transfers. It is a sign to check the embryo, the uterus, and how the two work together.
Recurrent pregnancy loss — Two or more pregnancy losses. Many couples have a cause that can be found and treated, so it deserves proper testing rather than 'just try again.'

Trigger Shot — An hCG (or GnRH-agonist) injection that tells maturing eggs to finish developing and release, timed so ovulation follows about 36–40 hours later. IUI is timed around ovulation, and IVF egg retrieval is done a little earlier, at about 34–36 hours.