Part A · three distinct concepts — often conflated, fundamentally different
Three separate dimensions — each independently variable
Biological sex
The biological characteristics: chromosomes, hormones, gonads, and anatomy. Primarily determined at conception; develops through fetal development and puberty. Mostly binary in distribution but includes variation (intersex).
Assigned at birth based on visible anatomy. May not reflect internal anatomy, chromosomes, or hormones.
Gender identity
A person's internal, psychological sense of their own gender — who they are. May or may not correspond with biological sex. Not the same as gender expression (how you present yourself). A core aspect of self.
Not a choice. Research suggests it is established early in development, with neurobiological components.
Sexual orientation
The pattern of emotional, romantic, and/or sexual attraction to others. Defined by the gender(s) a person is attracted to, not by their own gender. Distinct from gender identity — transgender people have all orientations.
Also not a choice. Strong evidence for biological and developmental (prenatal hormonal) contributions.
The key independence: These three dimensions can combine in any way. A person can be biologically male, identify as a woman (transgender), and be attracted to men (heterosexual) — or any other combination. Gender identity says nothing about sexual orientation; biological sex says nothing about gender identity. Each dimension is its own axis.
Three independent axes — any combination is possible
Part B · biological sex — the biology in detail
Chromosomal sex
XX, XY, and variations
Typically: XX = female, XY = male. The Y chromosome carries the SRY gene which triggers male development. But chromosomal variations exist: XXY (Klinefelter syndrome, ~1 in 500–650 males), XYY, X0 (Turner syndrome, ~1 in 2,500 females), XXX. Chromosomes determine initial gonadal development but are not the whole story — all subsequent sex characteristics depend on hormones.
Hormonal sex
Oestrogen, testosterone, and others
Both sexes produce both oestrogen and testosterone — in different proportions. Testosterone (produced primarily by testes, adrenals) drives male secondary characteristics. Oestrogen and progesterone (ovaries, adrenals) drive female secondary characteristics. Hormonal variation is continuous — there is no hard line. Some biological females have higher testosterone than some biological males.
Gonadal sex
Ovaries, testes, or ambiguous
Gonads develop from the same embryonic tissue (bipotential gonad). SRY gene triggers testes development; without SRY, ovaries develop by default. Some intersex conditions involve ambiguous or atypical gonadal development.
Intersex
~1.7% of the population (Fausto-Sterling estimate)
Intersex describes people whose biological sex characteristics don't fit typical definitions of male or female — in chromosomes, hormones, gonads, or anatomy. Examples: congenital adrenal hyperplasia (CAH, XX individuals with virilised anatomy), androgen insensitivity syndrome (XY individuals with complete or partial female anatomy). Intersex is not the same as being transgender.
Sex determination — the timeline
Genetically set, anatomically expressed later
Chromosomal sex is set at fertilisation. The embryo is anatomically undifferentiated until about week 6–7. SRY triggers testes development ~week 7; testosterone from fetal testes drives male anatomy week 8–12. Without this hormonal cascade, female anatomy develops. External genitalia differentiate from the same embryonic structures (homologous organs).
Sex is mostly binary, not entirely
Bimodal distribution, not a strict binary
The statement "biological sex is binary" is approximately true — the vast majority of people are clearly chromosomally, hormonally, and anatomically male or female. But variations exist at every level. The ~1.7% intersex estimate (narrower clinical definitions give ~0.018%) is comparable in scale to red hair. Biology accommodates the spectrum even if the distribution is strongly bimodal.
Fetal sex differentiation timeline
Part C · gender identity — the spectrum explored
Part D · sexual orientation — the full spectrum
Part E · the Kinsey scale — history and limitations
Alfred Kinsey's 0–6 scale (1948) — a landmark and a limitation
0
Exclusively heterosexual
1
Mostly hetero, incidental same-sex
2
Mostly hetero, more than incidental
3
Equally hetero and homosexual
4
Mostly homosexual, more than incidental
5
Mostly homosexual, incidental hetero
6
Exclusively homosexual
What it contributed
Kinsey's 1948 "Sexual Behavior in the Human Male" was groundbreaking: it quantified that non-heterosexual behaviour and attraction were far more common than society admitted, and challenged the idea that sexuality was simply binary. It introduced the idea of a spectrum of orientation. Revolutionised scientific and public understanding.
Its limitations
The scale only captures one dimension (same-sex vs opposite-sex attraction) and conflates behaviour with attraction. It doesn't capture asexuality (no attraction to anyone), pansexuality, or the distinction between romantic and sexual attraction. Modern models (Klein Sexual Orientation Grid, Storms model) attempt to address these gaps.
Part F · three important distinctions
Orientation vs behaviour vs identity
Three separate things
Orientation is who you are attracted to. Behaviour is who you have sex with. Identity is how you label yourself. A person can be attracted to both sexes (orientation), only have had opposite-sex relationships (behaviour), and identify as straight (identity). Or any other combination. These don't always align — and that's normal. Research focuses on attraction, not self-label or behaviour.
Romantic vs sexual attraction
Separable components
Sexual attraction: physical/sexual desire. Romantic attraction: desire for emotional intimacy, partnership, and romance. Most people experience both for the same gender(s). But some are romantically attracted to one gender and sexually to another. Asexual people may have strong romantic attraction without sexual. The two-axis model captures this better than the Kinsey scale.
Gender expression vs gender identity
How you present vs who you are
Gender expression is external: clothing, hair, mannerisms, pronoun preferences. Gender identity is internal: your sense of being a man, woman, neither, or other. These often align but don't have to. A cisgender man may have a feminine gender expression without this affecting his gender identity. Neither tells you about sexual orientation.
Sex assigned at birth vs gender
A medical observation vs a psychological reality
"Sex assigned at birth" (SAAB) refers to the sex recorded at birth based on visible anatomy — male, female, or intersex. It's a medical designation. Gender is the person's lived psychological experience. For cisgender people they align. For transgender and non-binary people they don't fully. The medical community now formally distinguishes these.
Part G · prevalence — what the numbers say
Population estimates — with important caveats about measurement
~3–4%
US adults identifying as gay or lesbian (Gallup 2023)
~5–6%
US adults identifying as bisexual (largest LGB subgroup)
~7.6%
Gen Z adults in US identifying as LGBT+ (vs 2.6% of Baby Boomers)
~0.5–1.7%
Population identifying as transgender (estimates vary widely by method)
~1%
Population identifying as asexual (varies by study: 0.4–4%)
Dot visualisation — 100 representative people, US adult population (approximate)
Straight (≈87%)
Gay/lesbian (≈3.5%)
Bisexual (≈5.5%)
Other LGBT+ (≈4%)
Why numbers vary so much: Stigma causes underreporting in less accepting environments. Self-labelling varies — many people attracted to the same sex don't use the label "gay" or "bisexual." Gen Z's higher rates reflect both genuine differences and greater willingness to identify. Measurement method matters enormously: anonymous surveys consistently produce higher rates than face-to-face interviews. The underlying rates of same-sex attraction are higher than the rates of self-identification as gay/lesbian/bisexual.
Part H · generational trends — how identification has changed
LGBT+ identification by US generation — Gallup longitudinal tracking
Why the trend is rising: The increase from Boomers to Gen Z is real and substantial. The leading explanations are: greater social acceptance and reduced stigma enabling honest self-reporting; wider awareness of identity labels (especially bisexual, non-binary, queer) enabling identification; possible genuine cohort effects from reduced social pressure against same-sex attraction. The full explanation is probably all three, with measurement playing a significant role.
Bisexual identification leads growth: The biggest driver of the increase is rising bisexual identification, particularly among women. Among Gen Z women, bisexual is more common than straight + gay combined in some surveys. This does not mean sexual behaviour has changed as dramatically — the gap between same-sex attraction (behaviour/attraction) and bisexual identity has historically been larger than the gap for gay/lesbian identification.
Part I · the two-axis model — romantic and sexual attraction separately
The romantic–sexual split: why one axis isn't enough
The Kinsey scale treats attraction as one-dimensional. But sexual and romantic attraction are empirically separable — most people experience them together, but for a meaningful minority they diverge. Explore combinations below.
Sexual attraction axis
Romantic attraction axis
Select one option from each axis to see how they combine.
Part J · the science of sexual orientation — what research shows
Lines of evidence — where the science points and its limits
Select a line of evidence to explore the research.
Part K · medical and legal history — the key milestones
How the medical and legal framing has evolved
1948
Kinsey publishes Sexual Behavior in the Human Male — first large-scale quantitative study of sexual behaviour. Introduces the 0–6 scale and demonstrates that same-sex behaviour is far more common than publicly acknowledged.
1952
APA's DSM-I lists "homosexuality" as a "sociopathic personality disturbance." This classification was not based on clinical evidence but on societal attitudes prevailing at the time.
1969
Stonewall riots, New York — patrons of a gay bar resist police raids. Widely credited as catalysing the modern LGBTQ+ rights movement.
1973
APA removes homosexuality from the DSM-II, citing lack of evidence that it constitutes a disorder. Replaced with "Sexual Orientation Disturbance" (distress about orientation), which was itself removed in 1987.
1990
WHO removes homosexuality from the ICD-10. May 17 is now celebrated as International Day Against Homophobia, Transphobia and Biphobia (IDAHOTB) to mark this date.
1991
Simon LeVay publishes study finding structural differences in the INAH-3 region of the hypothalamus between heterosexual and homosexual men, suggesting neurobiological components to orientation. Findings subsequently replicated with some refinements.
2003
Lawrence v. Texas — US Supreme Court strikes down sodomy laws, decriminalising same-sex activity across the United States.
2013
DSM-5 replaces "Gender Identity Disorder" with "Gender Dysphoria" — shifting focus from identity (not a disorder) to clinically significant distress. Major conceptual and terminological shift in transgender healthcare.
2015
Obergefell v. Hodges — US Supreme Court rules same-sex marriage is constitutionally protected. Similar milestones occurred earlier in Netherlands (2001, first country), Spain (2005), Canada (2005).
2019
ICD-11 (WHO) removes "Gender Incongruence" from the mental health chapter and reclassifies it under "Conditions related to sexual health." Formally establishes that being transgender is not a mental illness.
2019
Large genome-wide association study (GWAS) of ~470,000 people in Science finds no single "gay gene" — rather, dozens of genetic variants each with small effects, accounting for 8–25% of variance in same-sex behaviour. Genetic effects not sufficient for prediction at individual level.
Part L · global legal landscape — a snapshot
Same-sex relationships — legal status by region (approximate 2024)
Where marriage equality exists: Predominantly Western Europe, North and South America (notably including Brazil, Argentina, Colombia, Mexico), South Africa, Australia, New Zealand, and Taiwan (Asia's first, 2019). The pace of adoption has accelerated: from 1 country in 2001 to 36+ by 2024.
Where criminalisation remains: Primarily across sub-Saharan Africa, the Middle East, Central and Southeast Asia. Death penalty provisions exist in parts of Iran, Saudi Arabia, Yemen, Qatar, UAE, and under some interpretations of law in Nigeria and Pakistan. Over 60 countries still criminalise consensual same-sex activity.
Part M · safe sex & protection — health, autonomy, and informed choices
Why safe sex matters — four intersecting dimensions
Physical health
Unprotected sex carries risks of sexually transmitted infections (STIs) and, for people with reproductive capacity, unintended pregnancy. Many STIs are asymptomatic for long periods yet cause long-term harm or are transmissible to others. Consistent, correct use of protection dramatically reduces these risks.
Prevention is more effective than treatment for most STIs. Many are permanently manageable but not curable.
Consent and autonomy
Safe sex is inseparable from consent. Both people have the right to know the risks involved, to agree on protection methods, and to withdraw consent at any point. Removing or sabotaging protection without a partner's knowledge ("stealthing") is a form of sexual assault in many jurisdictions.
Informed consent means both partners understand what is and is not being used for protection and agree to it freely.
Emotional wellbeing
Anxiety about STIs or unintended pregnancy significantly affects sexual wellbeing and relationship satisfaction. Using protection consistently reduces this background stress. Open communication about sexual health also builds trust and intimacy in relationships.
Sexual health conversations, though sometimes awkward, consistently improve relationship quality and trust when approached honestly.
An important reframe: Safe sex is not about shame or fear. It is about informed autonomy. Understanding the options, their effectiveness, and how to use them correctly is a form of self-knowledge and mutual respect. No single method is right for everyone -- the best approach depends on relationship context, reproductive goals, health history, and personal values.
Consent and communication -- what clear, ongoing consent looks like in practice
FRIES framework (Planned Parenthood)
A widely used framework for understanding consent:
Freely given
Not under pressure, coercion, intoxication, or obligation.
Reversible
Anyone can change their mind at any time, even mid-activity.
Informed
Both parties know what they are agreeing to, including protection methods.
Enthusiastic
Consent is active and willing, not the absence of refusal.
Specific
Agreeing to one activity does not imply agreement to others.
Communication topics to address
Open discussion before or at the start of a sexual encounter normalises safe sex and reduces misunderstanding:
STI testing history -- when you were last tested and results.
Protection preferences -- which methods each partner is comfortable with.
Contraception -- whether either partner is using hormonal or long-acting methods.
Boundaries -- what each person is and is not comfortable with.
Relationship context -- expectations around exclusivity or other partners.
Consent and same-sex / queer relationships: Consent principles apply identically regardless of the genders involved. The specific risk profile changes (e.g., pregnancy risk is absent in many same-sex encounters; some STI transmission routes differ), but the need for communication, mutual agreement, and ongoing check-ins is universal.
Protection and contraception -- overview by category
Contraceptive effectiveness comparison -- typical use vs perfect use (% preventing pregnancy per year)
Barrier methods -- the only forms of contraception that also protect against STIs
External (male) condom
~98% effective (perfect use)
A sheath that fits over the penis, collecting semen and blocking transmission of body fluids. The only male-controlled method that prevents both pregnancy and STIs. Made of latex (most common), polyurethane, or polyisoprene (for latex allergy). Correct use: check expiry date, open carefully (no teeth), squeeze tip to remove air, roll down fully, withdraw before losing erection, hold base while withdrawing. Use a new condom for each act.
Internal (female) condom
~95% effective (perfect use)
A pouch inserted into the vagina (or anus for anal sex) before intercourse. Made of nitrile -- no latex allergy concern. Can be inserted up to 8 hours in advance. Offers the person with a vagina more control. Also protects against STIs. The outer ring remains outside the body. Do not use simultaneously with a male condom -- friction reduces effectiveness of both.
Dental dams
Barrier for oral sex
A thin sheet of latex or polyurethane placed over the vulva or anus during oral sex. Prevents skin-to-skin transmission of herpes, HPV, and fluid-borne STIs. Not widely distributed by default but can be improvised from a condom (cut lengthwise) or non-microwaveable plastic wrap. Particularly relevant for lesbian, bisexual women, and people engaging in oral-anal contact.
Diaphragm / cervical cap
~88% (typical use with spermicide)
A dome-shaped cup inserted to cover the cervix, used with spermicide. Does not protect against STIs. Must be fitted by a healthcare provider. Less commonly used than condoms or hormonal methods in most high-income countries, but an option for those who prefer non-hormonal barrier methods and accept the lower effectiveness against STIs.
Spermicide
~72% alone (not recommended as sole method)
Chemical agents (nonoxynol-9) that immobilise or kill sperm. Available as creams, gels, foam, or suppositories. No STI protection. Frequent use of nonoxynol-9 can irritate vaginal tissue and may actually increase STI susceptibility. Best used as a supplement to other methods, not alone.
Gloves for manual sex
Barrier for hand-to-genital contact
Latex or nitrile gloves reduce skin-to-skin STI transmission during manual stimulation of genitals or anus -- particularly relevant if either partner has cuts or sores on their hands, or in contexts where hygiene is a concern. Not a common topic in mainstream safe-sex education but relevant in many contexts.
Step-by-step: correct condom use
Select a step to see guidance.
Hormonal and long-acting contraceptives
Sexually transmitted infections -- prevention, testing, and treatment
Select an STI to see transmission, symptoms, testing, and treatment.
Prevention strategies beyond condoms
PrEP (Pre-Exposure Prophylaxis)
A daily antiretroviral medication (tenofovir/emtricitabine) taken by HIV-negative people to prevent HIV acquisition. When taken consistently, PrEP reduces HIV risk from sex by ~99%. Recommended for people at substantial HIV risk. Does not protect against other STIs -- condoms remain important.
PEP (Post-Exposure Prophylaxis)
Antiretroviral medication taken after potential HIV exposure. Must be started within 72 hours (sooner is better). Taken daily for 28 days. Approximately 80% effective when started promptly. Not a substitute for PrEP -- it is an emergency measure. Available at emergency departments and sexual health clinics.
Vaccination
HPV vaccine (Gardasil 9) prevents the strains responsible for ~90% of cervical cancers and most genital warts. Recommended for all people before sexual debut (ideally 9--12) and effective up to age 26 (and with discussion, to 45). Hepatitis B vaccine is standard childhood immunisation -- prevents a sexually transmissible liver infection.
Regular testing
Many STIs are asymptomatic. The CDC recommends annual STI testing for all sexually active people under 25, and for people with multiple partners regardless of age. Testing frequency should increase with number of partners. Knowing your status protects both you and your partners.
Emergency contraception -- what it is, how it works, and time windows
Levonorgestrel pill (Plan B / Next Choice)
Up to 120 hours
A high-dose progestogen that delays or inhibits ovulation. Most effective when taken within 24 hours (95% effective); effectiveness declines to ~58% by 72 hours; low effectiveness after 72 hours. Available over the counter in most countries. Less effective in people over 70 kg / 154 lb -- ulipristal acetate or copper IUD is preferred. Does not terminate an existing pregnancy.
Ulipristal acetate (ella / ellaOne)
Up to 120 hours
A selective progesterone receptor modulator -- delays or inhibits ovulation. More effective than levonorgestrel across the full 5-day window, and effectiveness does not decline as steeply over time. Equally effective up to 120 hours. Requires a prescription in some countries. Cannot be taken alongside combined hormonal contraceptives -- there is an interaction.
Copper IUD
Up to 120 hours -- most effective option
The copper IUD (e.g., Paragard) is over 99.9% effective as emergency contraception when inserted within 5 days of unprotected sex. Works by preventing fertilisation and implantation. Has the added benefit of continuing as highly effective long-term contraception for 5--10+ years. Requires a healthcare provider appointment. The best option for people over 70 kg.
How emergency contraception works -- and what it does not do
All emergency contraceptive methods work primarily by delaying or preventing ovulation -- preventing the egg and sperm from meeting. They do not end an established pregnancy (they are not abortifacients). This is confirmed by medical and scientific consensus. If a pregnancy is already implanted, emergency contraception has no effect on it.
Pregnancy options -- the full picture
If an unintended pregnancy occurs, the options are: continuing the pregnancy and parenting, continuing the pregnancy and pursuing adoption, or terminating the pregnancy (abortion). All are legitimate medical choices. Abortion is legal in most of Europe, North America, and Australia; laws vary significantly worldwide and within countries (notably the United States post-Dobbs 2022). The WHO classifies safe abortion as essential healthcare.
Myths, risks, and common mistakes -- debunked
Select a myth or mistake to see the evidence.
Part N · menstruation — biology, cycle, symptoms, products, culture
What a period actually is — biology in plain terms
The shedding event
A period is the monthly shedding of the uterine lining (endometrium) when pregnancy does not occur. The lining thickens every cycle in preparation for a possible implanted embryo. When no embryo arrives, hormones drop, the lining detaches, and the body expels it through the vagina over roughly 3 to 7 days.
Average total blood loss per period: 30–80 ml. Anything consistently above 80 ml is medically defined as heavy menstrual bleeding (menorrhagia).
What is in the flow
Menstrual fluid is not purely blood. It is roughly half blood and half a mix of endometrial tissue, cervical mucus, vaginal secretions, and small amounts of unfertilised egg material. The dark or brown colour often seen at the start or end is older, oxidised blood; bright red is fresher flow.
Clots up to the size of a 10-cent coin are normal. Frequent large clots are not, and they warrant a clinical conversation.
When it begins and ends
Menarche (first period) typically occurs between ages 9 and 15, with the global average sitting around 12. Menopause (final period) occurs on average around 51, defined retrospectively as 12 consecutive months without bleeding. Between those bookends sit roughly 450 cycles in a typical lifetime, a substantial fraction of a person's life.
Earlier menarche has shifted globally over the last century, attributed largely to improved nutrition and rising body fat percentages.
Who menstruates: Most cisgender women between menarche and menopause, but also many transgender men and non-binary people with a uterus who have not started testosterone or had a hysterectomy. Some intersex people menstruate; others do not. Pregnancy, lactation, hormonal contraception, certain medical conditions, and significant weight loss or athletic training can pause periods entirely. "People who menstruate" is the inclusive descriptor; "women" is approximately but not strictly equivalent.
The 28-day cycle — four phases, two organs, a hormonal dance
Explore each phase — what is happening hormonally and what it feels like
Why 28 days is an average, not a rule
Normal cycle length
21–35 days
Anywhere in this range counts as a regular cycle. The famous "28 days" is the population median, not a target. The follicular phase varies most between individuals (and cycle to cycle); the luteal phase is more fixed at around 14 days. A short luteal phase (under 10 days) can affect fertility and warrants investigation if conception is the goal.
Short cycles (polymenorrhoea)
Under 21 days
Persistently short cycles can indicate anovulation, thyroid dysfunction, perimenopause, stress, or hormonal imbalance. Occasional short cycles are not concerning, especially in the first few years after menarche or in the years approaching menopause when cycle irregularity is expected.
Long cycles (oligomenorrhoea)
Over 35 days
Common in adolescence and perimenopause. In adults of reproductive age, persistently long cycles can signal polycystic ovary syndrome (PCOS — affecting around 10% of people of reproductive age), thyroid disease, hypothalamic amenorrhoea (often from low body weight or intense exercise), or hyperprolactinaemia.
Absent periods (amenorrhoea)
No bleed for 3+ cycles
Primary amenorrhoea: no menarche by age 15. Secondary amenorrhoea: previously regular cycles that have stopped. Causes range from pregnancy (the most common) through hormonal contraception, breastfeeding, weight loss, athletic training, stress, PCOS, premature ovarian insufficiency, and pituitary disorders. A persistent absence warrants medical investigation.
Irregular cycles
Variation greater than 7–9 days
A few days of variation between cycles is entirely normal. Substantial unpredictability (where you genuinely cannot estimate when the next period will arrive) is worth tracking and discussing with a clinician. Common in the first 2–3 years post-menarche, in perimenopause, with PCOS, with significant stress or life changes, and after stopping hormonal contraception.
Tracking — why and how
Apps, calendars, or a notebook
Tracking reveals your own pattern, helps predict symptoms, supports conception or contraception decisions, and gives clinicians useful data. Note start date, flow intensity, pain, mood, and any unusual symptoms. Apps like Clue, Flo, and Natural Cycles are widely used; a basic calendar works equally well. Be aware that data privacy with some apps has been a documented concern, particularly in jurisdictions where reproductive choices are legally constrained.
Symptoms — what is normal, what is not
PMS and PMDD — when premenstrual symptoms are clinically significant
Premenstrual syndrome (PMS)
A cluster of physical and emotional symptoms appearing in the luteal phase (the week or two before a period) and resolving within a few days of bleeding starting. Affects roughly 75% of menstruating people to some degree.
Physical
Bloating, breast tenderness, headaches, fatigue, food cravings, mild cramping.
Regular exercise, sleep, reduced caffeine and alcohol, magnesium and B6 (modest evidence), tracking to anticipate. Hormonal contraception can flatten symptoms by removing the cyclical hormone swing.
Premenstrual dysphoric disorder (PMDD)
A severe form recognised in DSM-5. Affects roughly 3–8% of menstruating people. Symptoms are debilitating and disrupt work, relationships, or self-care. PMDD is not "bad PMS". It is a distinct neurobiological condition reflecting abnormal sensitivity to normal hormonal shifts.
Severity
Marked mood swings, intense irritability or anger, hopelessness, anxiety, sometimes suicidal ideation, all confined to the luteal phase and lifting at menstruation.
Diagnosis
Requires prospective symptom tracking across at least two cycles, with significant impairment confined to the luteal window. Retrospective recall is unreliable.
Treatment
SSRIs (effective even when taken only in the luteal phase), hormonal suppression of ovulation, cognitive behavioural therapy. PMDD is treatable and not a character flaw. Getting a name for it is often itself transformative.
When to see a clinician: Severe pain that disables you, bleeding lasting more than 7 days, soaking through a pad or tampon every hour for several hours, large clots, bleeding between periods, periods stopping for 3+ months outside of pregnancy or known cause, mood symptoms that affect your safety or functioning. Period pain that requires you to miss school or work regularly is not "just normal". Endometriosis, adenomyosis, and fibroids are common, under-diagnosed, and treatable.
Period products — the full landscape
Disposable pads
External, absorbent
Worn in underwear. Range from panty liners through to overnight or postpartum pads. Easy, no insertion required, widely available. Should be changed every 4–6 hours to prevent odour and irritation. Some people react to fragrances or plastics; unscented and cotton-topped options exist. Environmental footprint is the main drawback: a person uses thousands across a lifetime.
Tampons
Internal, absorbent
Inserted into the vagina, absorbing flow before it leaves the body. With or without applicator. Allow swimming and tighter clothing. Must be changed every 4–8 hours. Toxic shock syndrome (TSS) is a rare but serious risk associated with leaving tampons in too long or using higher absorbencies than needed. Use the lowest absorbency that suits your flow and change regularly.
Menstrual cups
Internal, reusable, 5–10 years
A soft silicone or rubber cup that sits in the lower vagina, collecting rather than absorbing. Emptied every 4–12 hours, rinsed, reinserted. Steep learning curve (often 2–3 cycles to feel confident), but very low cost over time and minimal environmental footprint. Holds more than a super tampon. Brands include DivaCup, Mooncup, Saalt, OrganiCup, and many regional options.
Menstrual discs
Internal, reusable or disposable
Similar concept to cups but sit higher, behind the pubic bone. Often allow mess-free sex during menstruation. Higher capacity than cups. Reusable versions (e.g., Nixit, Saalt Disc) are silicone; disposable versions (Flex) are single-use. Slightly trickier removal than a cup for beginners.
Period underwear
External, reusable, 2–3 years
Absorbent layers built into underwear (Thinx, Modibodi, Knix, others). Worn alone for light to moderate days or as backup with other products on heavier days. Washed and reused. Comfortable, leak-resistant, low-effort. Front-loaded cost is higher than disposables but cheaper over the product lifespan. Some early Thinx products were found to contain PFAS in 2020, and many brands now publish testing.
Reusable cloth pads
External, reusable, 3–5 years
Cotton or bamboo pads with snap-on wings, washed after use. Cheaper than period underwear, breathable, free of plastic, but require laundering after each use. Used worldwide and especially valuable where disposables are inaccessible or unaffordable. Brands include GladRags, Hannahpad, and many independent makers.
Choosing what works: No single product is "best". Flow intensity, comfort with insertion, lifestyle, environmental priorities, and budget all matter. Most people use a mix across a cycle (cup or tampon by day, pad or underwear at night, for instance). Trying new products outside of a stressful moment helps. Period poverty, the state of being unable to afford menstrual products, affects an estimated 500 million people globally and is increasingly addressed through free-product schemes in schools and public buildings (Scotland became the first country to make products free in 2020).
Cultural, social, and global perspectives — the social life of menstruation
Taboo and silence
Near-universal, varying in severity
Most cultures have historically treated menstruation as something to be hidden. Euphemisms abound across languages: "Aunt Flo," "shark week," "ces jours-là," "el mes," "having the painters in." Surveys consistently find that significant minorities of menstruating people feel shame, hide products at school or work, or avoid disclosing they are on their period. The taboo is gradually weakening in many places but remains powerful.
Religious practices
Varied, from restrictive to celebratory
Orthodox Judaism observes niddah: separation during menstruation, with ritual immersion (mikveh) after. Hindu traditions in parts of South Asia exclude menstruating people from temples or kitchens, though practices vary enormously by region and reform movements push back. Some Christian denominations historically restricted communion during menstruation. Islamic practice exempts menstruating women from fasting and prayer. Some Indigenous traditions celebrate menarche with rite-of-passage ceremonies.
Chhaupadi (Nepal)
Banned 2017, still practised
A practice in parts of rural western Nepal where menstruating people are isolated in huts away from the family home. Has caused deaths from cold, smoke inhalation, animal attacks, and assault. Criminalised in 2017 and pushed against by health workers and women's organisations, but persists in some regions. A stark illustration of how taboo can become lethal.
Period poverty
~500 million affected globally
Inability to afford menstrual products or to access clean water and private sanitation. Linked to school absenteeism, infections from improvised materials, and reduced economic participation. Addressed through free-product policies (Scotland 2020, New Zealand schools 2021, parts of the US and UK), tax removal ("tampon tax" abolitions across many jurisdictions), and NGOs distributing reusables.
Menstrual leave
Policy in several countries
Japan, South Korea, Indonesia, Taiwan, Zambia, and Spain (2023, the first European country) offer some form of menstrual leave. Debate continues about whether such policies reduce stigma and support those with severe symptoms or, conversely, reinforce stereotypes and discourage hiring. Take-up rates are often low even where the right exists, partly due to social pressure.
Activism and visibility
Rising since the 2010s
A wave of menstrual activism: period emoji campaigns, free-product legislation, art projects, athlete openness about cycle effects on performance, and renewed scientific funding into endometriosis and PMDD. The shift from euphemism to direct language ("period," "menstruation") is itself a cultural change. The phrase "menstrual equity" has entered policy vocabulary, framing access to products and information as a matter of basic rights.
The bigger picture: Menstruation sits at an intersection of biology, gender, religion, economics, and law. The same physiological event is celebrated in one culture, hidden in another, criminalised in a third. Improving menstrual experience worldwide is partly a medical project (better treatments for pain, endometriosis, PMDD), partly a material one (products, water, sanitation), and partly a cultural one (information, normalisation, language). The three reinforce one another.
Part O · Q&A
1. What is the difference between being transgender and being intersex?
They are completely different phenomena that are frequently confused. Intersex refers to biological variation — a person whose chromosomes, hormones, gonads, or anatomy don't fit typical male or female definitions. It's a biological condition, not a gender identity. Most intersex people identify as the gender they were assigned at birth. Transgender refers to gender identity — a person whose gender identity doesn't match the sex they were assigned at birth. A transgender person's biological characteristics are typically standard male or female; the mismatch is between their biology and their gender identity. A person could theoretically be both intersex and transgender, but they are distinct things. Intersex is a biological description; transgender is a description of the relationship between a person's sex assigned at birth and their gender identity.
2. What does gender dysphoria mean medically, and how is it different from general unhappiness about one's body?
Gender dysphoria (DSM-5 diagnosis) is clinically defined as significant distress or impairment caused by a marked incongruence between one's experienced or expressed gender and one's assigned gender, lasting at least 6 months. The key components: the distress must be clinically significant — affecting social, occupational, or other important areas of functioning. It's not simply being unhappy about one's appearance. Many transgender people experience dysphoria; some do not — being transgender doesn't require a diagnosis of dysphoria. The DSM-5 moved from "Gender Identity Disorder" to "Gender Dysphoria" in 2013, distinguishing the identity (which is not a disorder) from the distress caused by social context and bodily incongruence (which can cause genuine clinical suffering). The ICD-11 (WHO) uses "Gender Incongruence" and classifies it under sexual health rather than mental health — reflecting the consensus that being transgender is not a mental illness.
3. What is the difference between pansexual and bisexual? Why do some people prefer one term over the other?
The definitions overlap significantly, and many bisexual and pansexual people use the terms interchangeably. The most common distinction: bisexual originally meant "attraction to both men and women" — but most bisexual people and bisexual advocacy organisations now define it as "attraction to one's own gender and other genders" or simply "attraction to multiple genders." Pansexual explicitly means "attraction regardless of gender" — including non-binary, genderfluid, and agender people — with "pan" (all) emphasising the gender-blind nature of the attraction. The practical difference is often one of emphasis and political/community identity rather than meaningfully different experience. Some people prefer "bisexual" because of its history and community; others prefer "pansexual" because it explicitly includes non-binary people in a way they feel "bisexual" may not; others use both. Neither is more valid — they represent different frameworks for describing overlapping experiences.
4. What does medical transition involve, and what are the different steps?
Medical transition is not a single event but a range of possible interventions that a transgender person may pursue — some, all, or none. Social transition (not medical): changing name, pronouns, clothing, and social presentation — often the first step, can occur at any age. Hormonal transition: cross-sex hormone therapy — transgender women take oestrogen (and often anti-androgens) to feminise; transgender men take testosterone to masculinise. Effects include changes in body fat distribution, skin, body hair, voice (testosterone), breast development (oestrogen), and emotional changes. These happen over months to years. Puberty blockers: for adolescents, GnRH agonists pause puberty, buying time for decision-making. Effects are largely reversible. Surgical options vary widely — for transgender women: orchiectomy, vaginoplasty, facial feminisation surgery, breast augmentation. For transgender men: mastectomy (top surgery) is most common; phalloplasty or metoidioplasty for genital surgery. Not all transgender people pursue surgery — it is a personal decision based on dysphoria, health, finances, and individual needs. The medical standard of care is guided by WPATH (World Professional Association for Transgender Health) Standards of Care.
5. Is sexual orientation a choice? What does the scientific evidence say?
The scientific consensus is clear: sexual orientation is not a conscious choice. The evidence comes from multiple directions. Twin studies: identical twins show higher concordance for same-sex orientation than fraternal twins, suggesting a genetic component — but concordance is not 100%, indicating environment (likely prenatal) also plays a role. Prenatal hormonal exposure: the fraternal birth order effect (gay men statistically have more older brothers than heterosexual men) is explained by a maternal immune response to male-specific proteins that increases with each male pregnancy. The H-Y antigen hypothesis suggests this affects prenatal brain development. Brain structure: studies (beginning with LeVay 1991) found structural differences in the hypothalamus between heterosexual and homosexual men. Finger length ratios (2D:4D): a marker of prenatal androgen exposure, shows consistent differences between lesbian women and heterosexual women. Large-scale GWAS (2019, ~470,000 participants) found dozens of genetic variants associated with same-sex behaviour but no single "gay gene" — confirming a complex, polygenic, and partly environmental picture. The most important practical point: "conversion therapy" — attempts to change sexual orientation through psychological or religious intervention — is not only ineffective but causes documented psychological harm, and is banned by professional medical organisations worldwide on this basis.
6. What does research suggest about the origins of gender identity?
Research on the biological underpinnings of gender identity is ongoing but points to neurobiological and developmental factors. Key lines of evidence: Brain studies have found that certain brain regions in transgender women more closely resemble those of cisgender women than cisgender men, and similarly for transgender men — suggesting that brain development may be partially discordant with birth sex in transgender people. Twin studies show higher concordance for transgender identity among identical vs. fraternal twins, suggesting a heritable component. Prenatal hormone exposure: conditions that alter prenatal androgen exposure (e.g., congenital adrenal hyperplasia in XX individuals) are associated with higher rates of gender dysphoria and gender-nonconforming behaviour, though most affected individuals identify as women. Stability: gender identity is typically stable from early childhood (age 3–4) and does not change with social exposure. The consensus across APA, AMA, WPATH, and other major medical bodies is that being transgender reflects a normal variation in human development with biological underpinnings — not a choice, a pathology, or a social contagion. Childhood social desistance (children who identify as transgender and later identify as cisgender) is real but the statistics are contested — methodological problems in earlier studies mean earlier estimates (suggesting majority desistance) are now considered unreliable by most researchers.
7. What is the fraternal birth order effect and what explains it?
The fraternal birth order effect (FBOE) is one of the most replicated findings in the biology of sexual orientation: gay men, as a group, have a statistically greater number of older brothers than heterosexual men. For each older brother, the odds of a younger male sibling being gay increase by approximately 33%. This effect is specific to biological older brothers — it doesn't appear for adopted brothers, suggesting it's not a socialisation effect but a biological one. The leading explanation (Bogaert, Blanchard, and colleagues) is a maternal immune hypothesis: when a mother carries male fetuses, small amounts of a Y-linked protein called NLGN4Y (previously called HYYY antigen) cross the placental barrier into the mother's bloodstream. Some mothers develop an immune response. With each subsequent male pregnancy, the antibody response strengthens. These antibodies may cross back into the fetal brain and affect development of brain regions involved in sexual attraction — the INAH-3 region of the anterior hypothalamus specifically. A 2017 study (Bogaert et al.) found that mothers of gay sons with older brothers had significantly higher anti-NLGN4Y antibody levels than other mothers, providing the first direct biochemical evidence for the mechanism. The FBOE accounts for roughly 15–29% of gay men (those with older brothers) — meaning most same-sex orientation has other causes, but the effect is a clear, repeatable, and now mechanistically supported example of a prenatal biological influence on sexual orientation.
8. Hormonal contraceptives are very effective -- so why should someone still use condoms if they are on the pill?
Hormonal contraceptives prevent pregnancy through their effects on the reproductive system -- suppressing ovulation, thickening cervical mucus, and thinning the uterine lining. They have absolutely no effect on pathogens. They do not block the transmission of bacteria (chlamydia, gonorrhoea, syphilis), viruses (herpes, HIV, HPV, hepatitis B), or parasites (trichomoniasis). The pill, patch, ring, injection, implant, and all IUDs are silent on STI risk. Condoms are currently the only widely available method that addresses both pregnancy and infection simultaneously. For people in established, mutually monogamous relationships where both partners have been tested and are clear of STIs, relying solely on a hormonal method for pregnancy prevention is a reasonable and common choice. But for new partners, non-exclusive relationships, or any situation where STI status is unknown, combining hormonal contraception with condoms provides dual protection -- high effectiveness against pregnancy and meaningful reduction in STI transmission. This combination is sometimes called "dual protection."
9. What is the difference between emergency contraception and an abortion? Why does the distinction matter?
The distinction rests on when in the reproductive process each intervention acts. Emergency contraception (levonorgestrel, ulipristal acetate, or the copper IUD) works by preventing pregnancy from occurring in the first place -- primarily by delaying or inhibiting ovulation so that sperm and egg never meet. If fertilisation has already occurred, the evidence suggests emergency contraceptives do not prevent implantation, though this was once debated. The medical and scientific consensus is that pregnancy begins at implantation, not fertilisation -- this is the definition used by the American College of Obstetricians and Gynecologists and the WHO. By this definition, emergency contraception is not an abortifacient: it prevents pregnancy rather than terminating one. Abortion, by contrast, ends an established pregnancy after implantation -- through medication (mifepristone plus misoprostol, the "abortion pill") or a surgical procedure. The two are entirely different interventions acting at different points. The distinction matters because: (1) It is medically accurate and affects how people understand their options after unprotected sex; (2) Emergency contraception has been subject to political and religious controversy partly due to the incorrect belief that it causes abortion -- this has led to access barriers in some countries and US states; (3) Confusing the two can deter people from using emergency contraception when it would be appropriate and effective, leading to unintended pregnancies that might then require abortion.