The words, plainly.

Absorbency

Absorbency is how much fluid a product can take in. In Canada, tampon absorbency is standardised: “Super”, for example, means more than 9 and less than 12 grams of test fluid. A Super tampon has to fit that range, whatever the brand. Period pads, cups, discs and period underwear have no equivalent Canadian absorbency standard, so each maker uses its own scale.

Says who? Health Canada, Guidance for the Labelling of Medical Devices, Appendix 2: Labelling for Menstrual Tampons.

Read more: “Super” on a period pad and “Super” on a tampon are not the same thing

Adenomyosis

Adenomyosis is a condition in which the lining of the uterus grows into the muscle wall of the uterus. It can cause painful and heavy periods, pelvic pain and pain during sex. Some people have no symptoms. If your periods are very painful or very heavy, or have changed, that is a conversation for a healthcare provider.

Says who? NHS (UK), “Adenomyosis”, reviewed 2023-07-17.

Auto-dump

Also called: auto dumping.

Auto-dump is an informal name for a menstrual disc partly emptying on its own, usually when you pee. Clinicians explain that as the bladder empties, the disc’s position can change, “a phenomenon called ‘auto dumping,’ which has been advertised as an advantage of the menstrual disc”. Some people like it; others experience it as a leak.

Says who? Liberty et al., Obstetrics & Gynecology, 2023.

Cervix height

Also called: cervix-to-introitus distance.

Cervix height is how far the cervix, the lower end of the uterus, sits from the vaginal opening. Clinicians call it the “cervix-to-introitus distance”. It differs between people, and it matters for fit: some cups are made without stems for people whose distance “cannot fully accommodate a cup with a stem”. Makers’ sizing guides explain their own products.

Says who? Liberty et al., Obstetrics & Gynecology, 2023.

Clots

Also called: blood clots.

Clots are soft, jelly-like lumps of blood that can come out during a period. Canada’s SOGC lists “blood clots that are as big as a quarter or larger” among the signs of heavy menstrual bleeding. Those signs are worth discussing with a healthcare provider.

Says who? SOGC, yourperiod.ca, “Is my bleeding normal?”.

Endometriosis

Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus. It can cause painful periods, pain outside periods, pain with sex, and trouble getting pregnant. Canada’s SOGC says it affects about 10% of women and an unknown number of trans, non-binary and gender-diverse people. SOGC says the diagnostic delay in Canada is “at least five years”.

Says who? SOGC Endometriosis Hub.

A note on words: the SOGC page we cite here says “women”. We keep researchers’ words so we report their findings accurately. The Reading Room is for everyone who menstruates.

Flooding

Flooding is an everyday word, not a clinical term, for a sudden, very heavy gush of period blood that goes through a product quickly. Clinicians describe heavy bleeding in measurable terms. Canada’s SOGC lists “bleeding that soaks through one or more tampons or pads every hour for several hours in a row” as a sign of heavy menstrual bleeding worth discussing with a healthcare provider.

Says who? SOGC, yourperiod.ca, “Is my bleeding normal?”.

Heavy menstrual bleeding

Also called: HMB; menorrhagia (older term).

Heavy menstrual bleeding (HMB) is the clinical name for heavy periods. Canada’s SOGC describes it by signs such as needing more than one period pad at a time, bleeding for more than 7 days, or soaking a product every hour for several hours. “Menorrhagia” is the older name. FIGO, an international gynaecology body, decided to stop using it because such terms were “poorly defined and inconsistently used”.

Says who? Munro, “Practical aspects of the two FIGO systems…”, 2017; SOGC, yourperiod.ca.

Read more: “‘Super’ on a period pad and ‘Super’ on a tampon are not the same thing”, section “When heavy is worth a conversation”.

Lochia

Also called: postpartum bleeding.

Lochia is the bleeding and discharge after giving birth. It is not a period. It starts red and, according to HealthLink BC, turns pink within about a week, then white or yellow after about 10 days. A systematic review of 18 studies found that the average reported duration was 24 to 36 days, with wide variation.

Says who? Fletcher, Grotegut, James, Journal of Women’s Health, 2012; HealthLink BC, “Postpartum bleeding”, 2022.

Menstrual disc

Also called: disc.

A menstrual disc is a flexible device that collects period blood rather than absorbing it. Health Canada has licensed menstrual discs, reusable and single-use, as Class II medical devices. It sits higher in the vagina than a cup, covering the cervix and tucked behind the pubic bone. Clinicians describe a “collection basin, which is usually wider and shallower than a cup, holding between 30 and 79 mL”. They note that “Menstrual discs have no suction component”.

Says who? Health Canada, Medical Devices Active Licence Listing (MDALL); Liberty et al., Obstetrics & Gynecology, 2023. Placement: a 2011 clinical study in the Journal of Women’s Health (funded by the device’s developer), https://doi.org/10.1089/jwh.2009.1929.

Perimenopause

Perimenopause is the transition before menopause, when hormone levels shift and periods change. Canada’s SOGC describes skipped periods or shorter cycles, and heavy or light bleeding. It can begin 4 to 8 years before menopause and sometimes lasts 10 years or longer. Menopause is confirmed after 12 months in a row with no period. In Canada, the average age of menopause is 51.

Says who? SOGC Menopause Hub.

Period poverty

Period poverty is not being able to get what you need to manage a period. Canadian researchers define it as “the lack of access to menstrual products, sexual and reproductive health education, safe waste management, and adequate facilities”. They note that peer-reviewed Canadian data are still limited. If you need products now, see the help list at the end of this page.

Says who? Lee, Toory, Harrison, Canadian Journal of Public Health, 2024.

Period products

Also called: menstrual products.

Period products are the items people use to absorb or collect period blood. In the Reading Room, this means disposable period pads and liners, tampons, cups, discs, period underwear and reusable period pads. The Reading Room also covers comfort and care items. Definitions vary. For the federal workplace rule, Employment and Social Development Canada defines “menstrual product” narrowly: “tampons and menstrual pads”.

Says who? Employment and Social Development Canada, “Employer requirements: workplace menstrual products”.

PMDD

Also called: premenstrual dysphoric disorder.

PMDD is a severe, cyclical condition in which mood symptoms, such as depression, anxiety or irritability, appear in the one to two weeks before a period and ease within a few days after it starts. IAPMD, an international patient-advocacy association, describes it as “a cyclical hormone-based mood disorder”. It says PMDD is not a hormone imbalance. IAPMD distinguishes it from typical PMS. If your mood changes follow your cycle, that is a conversation for a healthcare provider.

If you are thinking about suicide, or worried about someone, call or text 9-8-8.

Says who? IAPMD, “About PMDD”.

PMOS (formerly PCOS)

Also called: PCOS; polycystic ovary syndrome (the former name).

PMOS is the new name for the condition long called PCOS, polycystic ovary syndrome. It stands for polyendocrine metabolic ovarian syndrome, a name agreed in 2026 through a global consensus. It affects hormones, metabolism and ovulation, and can cause irregular periods. The new name drops “cysts”: the researchers say the old name wrongly implied ovarian cysts. The researchers plan a transition period, so both names will appear for a while.

Says who? “Polyendocrine metabolic ovarian syndrome, the new name for PCOS: a multistep global consensus process”, The Lancet, 2026.

PMS

Also called: premenstrual syndrome.

PMS is the set of physical and emotional symptoms some women have in the days or weeks before a period. They can include mood swings, irritability, tiredness, bloating, breast tenderness and headaches. They can vary from month to month.

Says who? NHS (UK), “PMS (premenstrual syndrome)”, reviewed 2024-06-18.

A note on words: the NHS page we cite here says “women”. We keep researchers’ words so we report their findings accurately. The Reading Room is for everyone who menstruates.

Spotting

Also called: intermenstrual bleeding; bleeding between periods.

Spotting is light bleeding outside your usual period. Clinicians also call bleeding between periods “intermenstrual bleeding”. It has many possible causes, including hormonal contraception and hormonal changes. Canada’s SOGC lists bleeding between periods, particularly if you are not on birth control, as a change worth checking with a healthcare provider.

Says who? SOGC, yourperiod.ca, “Is my bleeding normal?”; healthdirect (Australia), “Bleeding between periods”.

Superabsorbent polymer

Also called: SAP.

A superabsorbent polymer (SAP) is a material made of tiny granules, usually polyacrylate, mixed into the core of many disposable period pads to lock fluid in. Researchers note that SAPs reduce surface wetness after absorbing and hold fluid under pressure, which helps keep it from coming back to the surface. Not every product contains SAP. Some makers list their core materials.

Says who? Birchall et al., Polymers, 2026.

TSS

Also called: toxic shock syndrome.

TSS is a rare but serious illness caused by toxins from bacteria. Health Canada requires tampon boxes to say that tampons “are associated with Toxic Shock Syndrome (TSS)”. HealthLink BC names tampon and menstrual cup use among the risks. Signs include high fever, vomiting or diarrhea, dizziness, fainting, or a rash that looks like a sunburn. If this happens while you are using a tampon or cup, remove it. Health Canada says to get immediate medical help; HealthLink BC says to call 9-1-1 or go to the nearest emergency department right away.

Says who? Health Canada, Appendix 2 and “Menstrual tampons”; HealthLink BC, “Toxic shock syndrome”.

Wicking

Wicking is drawing moisture away from the skin and spreading it through a fabric or layer, so the surface feels drier. The top layer of a disposable period pad is designed to do this. Clinicians describe period underwear as “generally… manufactured from multiple layers of polyester designed to wick moisture away from the skin”. The number of layers varies.

Says who? Liberty et al., Obstetrics & Gynecology, 2023; Birchall et al., Polymers, 2026.