Welcome to our Menstrual Health Glossary, a comprehensive, evidence-based reference guide designed to support better understanding of menstrual health, hygiene, and reproductive wellness.

This glossary defines commonly used terms related to menstrual products, biological processes, gynecological conditions, and cycle management. Whether you're new to menstruation, managing a specific health concern, or simply looking to deepen your knowledge, this resource offers clear, accurate, and scientifically grounded explanations to help you make informed decisions about your menstrual care.

Absorbency

The ability of a material to absorb and retain liquid. In the context of menstrual hygiene products, absorbency is a critical performance metric used to evaluate how much menstrual fluid the product can retain without leaking.

Amenorrhea

A medical condition characterized by the absence of menstruation during a woman’s reproductive years. It is categorized into two main types:

• Primary amenorrhea refers to the failure to initiate menstruation by age 15 in girls with normal growth and secondary sexual characteristics.
• Secondary amenorrhea is defined as the cessation of menstruation for three consecutive months in women with previously regular cycles, or for six months in women with irregular cycles, excluding pregnancy, lactation, or menopause as causes.

Breakthrough Bleeding

This is unscheduled vaginal bleeding or spotting that occurs between regular menstrual periods or during hormone-based contraceptive use, particularly during the initial months of starting oral contraceptives, the contraceptive patch, hormonal intrauterine devices (IUDs), or other hormonal methods.

It is typically light and occurs due to fluctuations or inadequate levels of circulating estrogen, which fail to stabilize the endometrial lining, leading to shedding of the uterine lining outside the expected menstrual cycle.

Cervical Mucus

A fluid secreted by the cervical glands located in and around the cervical canal. It plays a crucial role in reproductive physiology, particularly in fertility and the menstrual cycle. The composition, volume, and consistency of cervical mucus varies throughout the menstrual cycle in response to hormonal changes, primarily estrogen and progesterone levels.

Cervix

The lower, narrow end of the uterus that forms a canal between the uterus and the vagina. Anatomically, it typically measures approximately 2.5 to 3.5 centimeters in length and consists of two main regions: the ectocervix, which protrudes into the vagina, and the endocervical canal, which connects the uterine cavity to the vaginal environment. The external opening of the cervix, known as the external os, varies in shape depending on age, hormonal status, and childbirth history, typically round in women who haven’t given birth yet and slit-like in women who have already given birth.

Copper IUD (See also: “Hormonal IUD, Implant”)

A small, T-shaped, non-hormonal contraceptive device that is inserted into the uterus to prevent pregnancy. It is typically made of plastic and wrapped with a fine copper wire, which acts as a spermicide by releasing copper ions that are toxic to sperm. Once inserted, a copper IUD can provide long-term contraception lasting up to 10, depending on the brand and model.

Cramps (see also: “Dysmenorrhea”)

A common term for the pain or discomfort in the lower abdomen before or during menstruation. Medically, this is called dysmenorrhea, which may range from mild to severe. The pain is primarily caused by the contraction of the uterine muscles in response to the release of prostaglandins, biochemicals that facilitate the shedding of the uterine lining during menstruation. Higher levels of prostaglandins are associated with increased frequency and intensity of uterine contractions, leading to stronger cramps.

Dilation and Curettage (D&C)

This is a minor surgical procedure in which the cervix is dilated to allow the insertion of surgical instruments into the uterus to remove part of the uterine lining (endometrium). This is done using a curette, a spoon-shaped instrument, for diagnostic or therapeutic purposes. D&C is commonly performed to diagnose or treat abnormal uterine bleeding, remove tissue after a miscarriage or abortion, or investigate the cause of infertility.

Discharge

Vaginal discharge is a fluid secreted by glands in the cervix and vaginal walls that serves to maintain vaginal hygiene, protect against infection, and support reproductive function. It is composed primarily of water, electrolytes, epithelial cells, cervical mucus, and various microorganisms that contribute to maintaining the acidic environment (pH 3.8–4.5) of the vagina.

The volume, texture, and color of discharge may vary depending on the menstrual cycle phase, hormonal fluctuations, age, and health status.

Disposable Pads

Disposable pads, also known as sanitary pads or menstrual pads, are single-use absorbent products designed to absorb menstrual fluid during menstruation. Constructed primarily from layers of non-woven fabrics, superabsorbent polymers (SAP), and polyethylene back sheets, these products offer external protection by adhering to the inner lining of underwear. They are among the most commonly used menstrual hygiene products globally, particularly in higher- and middle-income countries.

Dysmenorrhea (see also: “Cramps”)

A medical term that refers to painful menstrual cramps originating in the lower abdomen, occurring immediately before or during menstruation. It is classified into two types:

• Primary dysmenorrhea involves recurrent, cramp-like pain associated with menstruation in the absence of any identifiable pelvic pathology. It typically begins within 6 to 12 months after menarche (onset of menstruation) and is most common in women under the age of 25.
• Secondary dysmenorrhea, on the other hand, results from identifiable pelvic conditions such as endometriosis, adenomyosis, fibroids, or pelvic inflammatory disease. It is more likely to occur in older women and may become progressively worse over time.

Endometriosis

A chronic, often painful gynecological disorder in which tissue similar to the endometrium (the lining of the uterus) grows outside the uterine cavity. These ectopic endometrial-like tissues are most commonly found on the ovaries, fallopian tubes, pelvic peritoneum, and other pelvic structures, but in rare cases may occur in locations such as the lungs or brain. The lesions respond to hormonal fluctuations of the menstrual cycle, often resulting in inflammation, scarring, adhesions, and the formation of ovarian cysts known as endometriomas.

Estrogen

A group of steroid hormones that play a critical role in the regulation of the female reproductive system and the development of secondary sexual characteristics. The three major naturally occurring estrogens in women are estradiol, estrone, and estriol, with estradiol being the most potent and predominant during reproductive years. Estrogens are primarily synthesized in the ovaries, but they are also produced in smaller amounts by the adrenal glands, placenta (during pregnancy), and adipose tissue.

The table below compares the three main types of estrogen, highlighting their primary sources, dominant life stages, and typical blood concentration ranges.

Estrogen Type	Primary Source	Life Stage Dominance	Known Concentration Range in Blood
Estradiol	Ovaries	Reproductive years	30–400 pg/mL
Estrone	Adipose tissue, ovaries, adrenal glands	Postmenopause	10–138 pg/mL
Estriol	Placenta	Pregnancy	Up to 14,000 pg/mL

Flow (Menstrual)

Flow refers to the volume and rate at which menstrual blood and endometrial tissue are expelled from the uterus through the vagina during menstruation. Flow is typically categorized as light, moderate, or heavy, based on the quantity of blood loss per cycle, as well as the frequency of absorbent product changes required by the individual.

Follicular Phase

The follicular phase is the first phase of the menstrual cycle, occurring between the first day of menstruation and ovulation. It typically lasts about 10 to 14 days, but can vary significantly among individuals and cycles. Hormonal changes in the follicular phase initiate the development of ovarian follicles, one of which will mature to release an egg during ovulation.

Gynecologist

A medical doctor who specializes in diagnosing, treating, and managing conditions related to the female reproductive system, including the uterus, ovaries, fallopian tubes, cervix, vagina, and vulva. Gynecologists are trained to address menstrual disorders, fertility issues, sexually transmitted infections (STIs), hormonal imbalances, gynecological cancers, and menopause-related changes.

Hormonal Balance

The state in which hormones are produced, secreted, and regulated at optimal levels to support critical physiological processes in the human body. In individuals assigned female at birth, this balance involves key reproductive hormones including estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), which fluctuate cyclically during the menstrual cycle.

Hormonal IUD (See also: “Copper IUD, Implant”)

A small, T-shaped contraceptive device inserted into the uterus that releases a synthetic progestin hormone, typically levonorgestrel, to prevent pregnancy. It is a form of long-acting reversible contraception (LARC) with effectiveness rates over 99% when properly inserted and maintained. Hormonal IUDs function primarily by thickening cervical mucus to block sperm from reaching an egg, thinning the endometrial lining to prevent implantation, and in some cases, suppressing ovulation.

Hormone Replacement Therapy (HRT)

Refers to the clinical administration of estrogen or a combination of estrogen and progesterone to alleviate symptoms associated with hormonal decline, primarily during menopause. It is commonly prescribed to manage vasomotor symptoms such as hot flashes, night sweats, and vaginal dryness, and to prevent osteoporosis in postmenopausal individuals.

Implant (Contraceptive) (See also: “Copper IUD, Hormonal IUD”)

A contraceptive implant is a small, flexible rod approximately 4 cm in length and 2 mm in diameter that is inserted subdermally (under the skin), typically in the upper arm, to provide long-acting reversible contraception (LARC). The implant releases a synthetic progestin hormone, most commonly etonogestrel, into the bloodstream at a controlled rate. It prevents pregnancy primarily by inhibiting ovulation, thickening cervical mucus to block sperm, and thinning the endometrial lining to reduce the likelihood of implantation.

Irregular Periods

Irregular periods refer to menstrual cycles that deviate significantly from the average cycle length of approximately 28 days. Clinically, a menstrual cycle is considered irregular if the length between periods varies by more than seven to nine days from month to month, or if the total cycle length is consistently shorter than 21 days or longer than 35 days.

Luteal Phase

This is the latter phase of the menstrual cycle, lasting from ovulation to the onset of menstruation. It typically spans 11 to 17 days, with an average duration of 14 days in individuals with regular cycles. During this phase, the ruptured ovarian follicle transforms into a structure known as the corpus luteum, which secretes the hormone progesterone. Elevated progesterone levels help maintain the endometrial lining of the uterus in preparation for potential embryo implantation.

Menarche

The first occurrence of menstruation in a female human, marking the onset of reproductive capability and one of the key milestones of puberty. It typically occurs between the ages of 10 and 16 years, with global averages ranging from 12 to 13 years old, though age of onset can be influenced by genetic, nutritional, socioeconomic, and environmental factors.

Menopause

The permanent cessation of menstrual periods resulting from the loss of ovarian follicular activity. It is retrospectively diagnosed after 12 consecutive months of amenorrhea without any other pathological or physiological cause. The average age of natural menopause is approximately 51 years in most populations, although it can range from 45 to 55 years. Menopause marks the end of a woman’s reproductive years and is associated with a significant decline in circulating estrogen and progesterone levels produced by the ovaries.

Menstrual Cup (See also: “Menstrual Disc”)

A reusable, disc or bell-shaped device made of medical-grade silicone, rubber, or elastomer that is inserted into the vaginal canal to collect menstrual fluid. Unlike disposable pads or tampons, which absorb blood, menstrual cups collect it, allowing for longer use per cycle. A typical menstrual cup can collect between 15 to 30 milliliters of fluid, depending on its size and design, which is roughly twice the capacity of a super-absorbency tampon.

Menstrual Cup Wipe

A menstrual cup wipe is a pre-moistened, disposable cleaning cloth specifically formulated for sanitizing a menstrual cup when access to clean water and soap is limited. These wipes are commonly made using skin-safe, alcohol-free solutions that help remove menstrual residue and reduce microbial growth without damaging the medical-grade silicone found in most menstrual cups. They are individually wrapped for portability and are often marketed for use in public restrooms, during travel, or in outdoor settings.

Nixit Menstrual Cup Wipes

Menstrual Cycle

A recurring physiological process in individuals with female reproductive systems, characterized by hormonal fluctuations and changes in the uterus and ovaries, which prepare the body for potential pregnancy. A typical cycle lasts approximately 28 days, but durations between 21 and 35 days are considered normal in adults.

Menstrual Disc (See also: “Menstrual Cup”)

A reusable or single-use, internal menstrual product designed to collect menstrual fluid. Unlike tampons or menstrual cups that sit in the vaginal canal, menstrual discs are placed in the vaginal fornix where they rest horizontally to collect menstrual blood. Discs are typically made from medical-grade material, holds a higher capacity than traditional cups, and are designed to conform to the body’s anatomy, providing leak-free menstruation management for up to 12 hours per use.

Nixit Menstrual Disc

Menstruation

The regular discharge of blood and mucosal tissue from the inner lining of the uterus (endometrium) through the vagina. This process is part of the menstrual cycle and typically occurs in individuals with a uterus from puberty (menarche) until menopause, excluding periods of pregnancy and certain health conditions. Menstruation is regulated by hormonal fluctuations, primarily involving estrogen and progesterone.

Ovulation

Ovulation is the phase of the menstrual cycle during which a mature ovarian follicle ruptures and releases an oocyte (egg) into the fallopian tube, where it may be fertilized by sperm. It typically occurs once per cycle, approximately midway through, around day 14 in a 28-day cycle, although timing can vary between individuals and cycles. Ovulation is regulated by the hypothalamic–pituitary–gonadal axis and is triggered by a surge in luteinizing hormone (LH), which follows a gradual rise in estrogen levels produced by the developing follicle.

Ovulation Predictor Kits (OPK)

These are over-the-counter diagnostic tools designed to detect the surge in luteinizing hormone (LH) in urine that precedes ovulation. Ovulation is typically triggered by a peak in LH levels, which occurs approximately 24 to 36 hours before the release of an egg from the ovary. OPKs aid individuals in identifying the most fertile window of the menstrual cycle, which can enhance timing for conception.

Pads

Also known as sanitary pads or menstrual pads, are absorbent products designed to be worn externally in the underwear to manage menstrual flow. They are classified as a type of menstrual hygiene product and are typically made of layers of absorbent material such as cellulose fiber, absorbent polymers, and a fluid-impermeable backing to prevent leakage.

Period Blood Color

Period blood color refers to the visual appearance of menstrual blood, which can vary in hue and consistency depending on several physiological factors, including the age of the blood, flow rate, hormonal fluctuations, and underlying health conditions. The color of menstrual blood typically ranges from bright red to dark brown or even black. Bright red blood generally indicates fresh, active bleeding, while darker shades may signal older blood that has oxidized inside the uterus or vaginal canal before being expelled.

Period Delay

The postponement of the onset of menstruation, typically achieved through hormonal means. This is commonly undertaken for personal, medical, or social reasons and is usually facilitated using oral progestogens such as norethisterone or through continuous use of combined oral contraceptives (COCs).

Period Symptoms

Also referred to as menstrual symptoms, are a range of physiological and psychological changes that occur in individuals during the menstrual phase of the menstrual cycle. These symptoms typically begin one to two days before menstruation and can persist into the early days of the period. They result from hormonal fluctuations, particularly in estrogen and progesterone levels, and vary significantly in intensity and presentation between individuals.

Premenstrual Dysphoric Disorder (PMDD)

A severe, chronic medical condition characterized by pronounced emotional, behavioral, and physical symptoms that occur in the luteal phase of the menstrual cycle and resolve shortly after the onset of menstruation. PMDD is classified as a depressive disorder distinct from Premenstrual Syndrome (PMS) due to its disabling psychiatric impact and functional impairment.

Premenstrual Syndrome (PMS)

A clinically recognized set of physical, emotional, and behavioral symptoms that occur in the latter half of the menstrual cycle, typically during the luteal phase, and resolve with the onset of menstruation. PMS affects an estimated 20% to 40% of menstruating individuals to varying degrees of severity, with approximately 3% to 8% experiencing symptoms severe enough to disrupt daily functioning.

Reusable Pads

Reusable pads are washable, absorbent cloth menstrual products designed to be worn externally in the underwear to collect menstrual flow. Unlike disposable sanitary pads, reusable pads can be laundered and reused multiple times. They are commonly made of layers of absorbent textiles, often featuring a moisture-wicking top layer and a waterproof or water-resistant backing layer to prevent leakage.

Spotting

This refers to light vaginal bleeding that occurs outside of a regular menstrual period. It is generally characterized by the release of a small amount of blood, often insufficient to require the use of a pad or tampon. The blood is typically lighter in color (pink, brown, or rust-red) compared to typical menstrual flow and may appear sporadically or continuously for a short period of time.

Tampon

A cylindrical absorbent device designed to be inserted into the vaginal canal during menstruation to absorb menstrual fluid internally. Tampons are typically made from a blend of cotton and rayon or 100% cotton, and are available in different sizes and absorbencies to accommodate varying menstrual flow levels. Most tampons expand widthwise or lengthwise as they absorb fluid and can be inserted manually or using an applicator made of cardboard or plastic.

Below is a table comparing tampons to other menstrual products:

	Tampon	Menstrual Cup	Menstrual Disc	Sanitary Pad
Reusable	No (Disposable	Yes (Reusable up to 10 years)	Yes (Reusable discs) / No (Disposable discs)	Yes (Reusable cloth) / No (Disposable pads)
Wear Time	4–8 hours	Up to 12 hours	Up to 12 hours	4–8 hours
TSS Risk	Yes	Extremely low	Extremely low	No
Insertion Required	Yes	Yes	Yes	No

Toxic Shock Syndrome (TSS)

A rare, acute, and potentially life-threatening condition caused by bacterial toxin production, most commonly from Staphylococcus aureus or Streptococcus pyogenes. It is characterized by the sudden onset of high fever, hypotension, diffuse macular erythroderma (sunburn-like rash), and multi-organ dysfunction. TSS was first recognized in the late 1970s and is historically linked with high-absorbency tampon use, although it can also arise from surgical wounds, burns, and other localized infections.

Vaginal Wash

A vaginal wash is a liquid cleansing solution formulated specifically for external use on the vulvar area. It is designed to maintain or support the natural pH of the vaginal environment, which discourages the growth of pathogenic microorganisms and supports the proliferation of beneficial lactobacilli species.

Vasomotor Symptoms

Vasomotor symptoms (VMS) are transient, episodic disturbances of thermoregulation characterized primarily by sudden sensations of heat, often with flushing and night sweats, typically arising during the menopausal transition and early postmenopause. They are associated with narrowing and instability of the hypothalamic thermoneutral zone linked to estrogen withdrawal and altered signaling in hypothalamic KNDy (kisspeptin/neurokinin B/dynorphin) neurons, including neurokinin B and its receptor (NK3R).