Contraceptive Methods
Contraceptive methods are techniques, devices, or medications used to prevent pregnancy by inhibiting ovulation, fertilization, or implantation.
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References
[1] Lecture slides: CFB (OG03) Fertility Regulation.pdf (contraceptive methods, efficacy and eligibility) [2] Lecture slides: Block C - The woman needs that drug_ Oral contraceptives, Drugs affecting uterine motility.pdf (combined and progestogen contraception)
Contraceptive Methods
Contraception refers to the deliberate prevention of pregnancy through various methods, serving both as a population health strategy and as an individual means of family planning. Without proper contraceptive practices, undesired pregnancies burden individuals and society with psychosocial, financial, and health consequences — including risks associated with termination of pregnancy [1].
"Contraception is a choice, not a prescription!" — the method must be tailored to the individual's needs and preferences [1].
Who it applies to: Any person of reproductive potential (and their partner) seeking to delay, space, or limit pregnancy.
What a safe clinician must NOT miss:
- Contraindications to combined hormonal methods (especially VTE risk, smoking > 35 years, hypertension, migraine with aura)
- Drug interactions (especially enzyme-inducing AEDs and anticonvulsants reducing efficacy of hormonal contraception) [5]
- Screening for STI risk (some methods do NOT protect against STIs)
- The patient's autonomy and informed consent — never be prescriptive or judgemental
For each contraceptive method, you shall know the mechanisms of action, efficacy, method of use, benefits and drawbacks, and contraindications. [1]
- Efficacy is expressed as failure rate per 100 women-years (typical use vs. perfect use) — know both figures.
- Reversibility — distinguish permanent (sterilisation) from reversible methods.
- User-dependence — methods requiring daily/coital compliance have wider gaps between typical and perfect use.
- Dual protection — only barrier methods (condoms) reduce STI/HIV transmission.
- Mechanism of action — suppression of ovulation, barrier to sperm, hostile endometrial/cervical environment, or combination.
- Contraindications are method-specific; oestrogen carries the most restrictions.
- Non-contraceptive benefits matter (e.g. menstrual regulation, acne, endometriosis).
- Emergency contraception is a safety net, not a primary method.
- Counselling approach — shared decision-making centred on patient goals, medical eligibility, and lifestyle.
"Family planning care should not have a singular focus of preventing unintended pregnancy… focus on people reaching their desired reproductive outcomes by supporting them to make informed decisions about their fertility and contraceptive use that are aligned with their preferences and reproductive goals." [2][3]
Understanding contraception requires understanding the menstrual cycle:
| Phase | Events | Relevance to Contraception |
|---|---|---|
| Follicular (Day 1–14) | FSH stimulates follicular development → rising oestradiol | COC/POP suppress FSH → inhibit folliculogenesis |
| Ovulation (Day ~14) | LH surge triggers ovum release | Ovulation suppression is the primary mechanism of hormonal contraception |
| Luteal (Day 14–28) | Corpus luteum secretes progesterone → endometrial maturation | Progestogens thin endometrium, thicken cervical mucus |
| Menstruation | Withdrawal of progesterone → endometrial shedding | Pill-free interval mimics progesterone withdrawal |
- Ovum viability: ~24 hours post-ovulation [1]
- Sperm viability: up to 7 days in the female genital tract [1]
- This gives a fertile window of approximately Day 8–19 in a regular 28-day cycle
I. Natural Methods
Based on periodic sexual abstinence around the time of ovulation. The ovum lives only ~24 hours after ovulation; sperm is viable for up to 7 days. [1]
| Method | Rule | Key Detail |
|---|---|---|
| Standard Days Method | Abstinence Day 8–19 | Only for women with regular 26–32 day cycles; not suitable if > 2 cycles outside this range in past year [1] |
| Calendar / Rhythm Method | Abstain from (shortest cycle – 20) to (longest cycle – 10) | Based on past 12 months of cycle data [1] |
| BBT Method | Abstain from Day 1 of menses until 3rd consecutive day of BBT elevation [1] | BBT shows slight fall at ovulation then rises ~0.5°C and stays elevated until next menses |
| Cervical Mucus (Billings) Method | Abstain when mucus becomes thin, clear, stretchy, slippery → until 4 days after mucus cessation [1] | |
| Sympto-thermal | Combine BBT + cervical mucus: abstain when mucus becomes sticky/moist → until 3rd day of BBT shift OR 4th day after mucus cessation, whichever is later [1] | |
| Urine LH Test | Over-the-counter kits detect LH surge | None is recommended for contraceptive purpose [1] |
Advantages: No religious objection, no equipment/medication, no physical side effects, shared responsibility enhancing partner communication [1]
Disadvantages: Highly dependent on commitment and motivation of both partners. Effectiveness lower than most other methods. Failure rate in typical use: 24–40 per 100 women-years. [1] Requires learning period and daily monitoring.
- Not reliable because pre-ejaculatory fluid may already contain sperms [1]
Prevent conception by separating ovum from sperm by mechanical means or spermicides. No physical side effects, provide immediate contraception, easily accessible. User-dependent — rely on motivation and compliance. [1]
| Method | Details | Failure Rate (typical use, per 100 women-years) |
|---|---|---|
| Male condom | Thin rubber sheath over penis; also reduces HIV/STI transmission; breakage/slippage possible; latex allergy in some; NOT to be used with oil-based lubricants [1] | Up to 18 |
| Female condom (Femidom®) | Inserted into vagina before penetration; under woman's control; hanging-out part may look awkward; more expensive [1] | ~21 |
| Diaphragm + spermicide | Thin plastic cap with elastic rim; various sizes; placed across upper vagina with spermicidal jelly/cream | 6–20 |
| Cervical cap | Worn over cervix; more tedious to use | Similar to diaphragm |
Spermicides
- Available as jelly, cream, foaming tablet, film, sponge [1]
- Using spermicides alone → relatively high failure rate [1]
- May cause vaginal irritation and discharge
- Frequent use of nonoxynol-9 can increase HIV/STD risk via vaginal epithelial damage → should NOT be used in those at high risk for HIV/STD [1]
- Spermicide-lubricated condoms do NOT provide additional protection against pregnancy or STD → no longer encouraged [1]
Exam Point
Never recommend spermicide-only methods or spermicide-coated condoms as first-line. Know that nonoxynol-9 increases HIV transmission risk in high-risk individuals.
III. Hormonal Contraceptives
Composed of combined (oestrogen + progestogen) or progestogen-only regimens. Very effective reversible methods: failure rate < 0.5 per 100 women-years with perfect use, up to 9 per 100 women-years in typical use. Do not interrupt spontaneity of coitus. [1]
Forms available in Hong Kong: [1]
- Combined oral contraceptives (COCs)
- Progestogen-only pills (POPs)
- Progestogen-only injectable
- Combined injectable contraceptives (CICs)
- Transdermal contraceptive patch
A. Combined Oral Contraceptive (COC) Pills
Each COC pill contains an oestrogen (E) + a progestogen (P). Most common oestrogen is ethinyl oestradiol (EE). Progestin varies by generation. [2]
| Generation | Example Progestin | Key Feature |
|---|---|---|
| 1G | Norethisterone | Older, more androgenic |
| 2G | Levonorgestrel | Most widely studied, lowest VTE risk among COCs |
| 3G | Desogestrel, gestodene | Less androgenic, slightly higher VTE risk |
| 4G | Drospirenone | Anti-androgenic + anti-mineralocorticoid; used in Yasmin®/Yaz® |
Each hormone-containing pill taken continuously for 21 or 24 days, then hormone-free pills for remaining 7 (21/7 regimen) or 4 (24/4 regimen) days of cycle to allow bleeding. [2]
- Yasmin®: 0.03 mg ethinyl oestradiol + 3 mg drospirenone (21/7)
- Yaz®: 0.02 mg ethinyl oestradiol + 3 mg drospirenone (24/4)
Hormone-free period: oestrogen withdrawal → no negative feedback on FSH → some follicular development → endogenous oestradiol secretion → endometrial growth → then atrophy and withdrawal bleeding. [2]
Shorter hormone-free interval (24/4 vs 21/7) = better efficacy (less well-developed follicle) BUT increased chance of unscheduled breakthrough bleeding. [2]
- Oestrogen component:
- Suppresses FSH → inhibits follicular development
- Stabilises endometrium (reduces breakthrough bleeding)
- Progestogen component:
- Suppresses LH surge → prevents ovulation (primary mechanism)
- Thickens cervical mucus → hostile to sperm penetration
- Thins endometrium → less receptive to implantation
- Reduces tubal motility
| Component | Side Effect | Clinical Note |
|---|---|---|
| Oestrogen | Nausea, breast tenderness, headache, fluid retention | Dose-related |
| Oestrogen | Thrombotic conditions: DVT, PE, stroke, MI | Endothelial dysfunction → pro-thrombotic state, enhanced by smoking; increased coagulation — increased synthesis of clotting factors [2] |
| Oestrogen | Hypertension | More activated renin-angiotensin-aldosterone system; also promotes thrombosis [2] |
| Progestogen | Menstrual irregularities (most common with POP), weight gain, mood changes, acne (androgenic progestins), reduced libido |
Breakthrough Bleeding [2]
Oestrogen breakthrough bleeding: when exogenous oestrogen with atrophic progestogen-dominant endometrium; the endometrium thins and breaks through at unpredictable intervals. Progestogen breakthrough bleeding: occurs with progestogen-only methods where endometrium becomes atrophic and unstable. [2]
- "Oestrogen dose too high" → nausea, headache, fluid retention, breast tenderness, thrombotic events
- "Oestrogen dose too low" → breakthrough bleeding
- "Progestin dose too high" → weight gain, depression, acne, decreased libido
- "Progestin dose too low" → breakthrough bleeding, menstrual irregularities
Contraindicated in pregnancy, breast cancer, and other conditions (that allow usage of POP instead) [2]
| Absolute Contraindications (WHO Category 4) | Rationale |
|---|---|
| Smokers > 35 years old | Synergistic CVD risk with oestrogen |
| Known cardiovascular or coronary artery disease | Oestrogen pro-thrombotic |
| Thromboembolic disorders (current/past DVT, PE) | Oestrogen increases clotting factors |
| Thrombophlebitis | |
| Migraine with aura | Increased stroke risk |
| Uncontrolled hypertension | |
| Active liver disease / liver tumour | Impaired oestrogen metabolism |
| Breast cancer (current) | Hormone-sensitive tumour |
| Pregnancy | Teratogenic concern |
High-Yield Drug Interaction
AEDs (anti-epileptic drugs) affect efficacy of ALL hormonal contraception (COCP, progestogen implants). Advise barrier contraception (condom, copper IUCD) or increase hormonal dosage if must use hormonal methods. [5]
- Regulation of menstrual cycle
- Reduction of dysmenorrhoea
- Treatment of acne (especially with anti-androgenic progestins like drospirenone)
- Reduced risk of ovarian and endometrial cancer
- Treatment of endometriosis symptoms
- Management of PCOS symptoms
Combined OC pills: downregulate HPG axis → ↓ ovarian androgen secretion → effective in reducing both inflammatory and comedonal acne lesions. Must balance against risks: ↑ CVS risk, ↑ VTE, ↑ Ca breast, ↑ Ca cervix. [7]
Slightly lower efficacy than COC because ovulation is not always inhibited — progestin dose in POP much lower than in COC → less inhibition on FSH → some follicular development and oestradiol release → possible ovulation from oestradiol-triggered LH surge. [2]
- Most commonly taken every day (28-pill pack) without pill-free period [2]
- Exception: drospirenone POP taken for 24 days + 4 days placebo [2]
Key mechanism: Primarily thickens cervical mucus + thins endometrium; ovulation inhibited inconsistently
Who should use POP:
Used by those contraindicated to COCs, usually due to oestrogenic/oestrogen-like effects on vascular conditions: [2]
- Smokers > 35
- History of/current VTE
- Hypertension
- Cardiovascular disease
Contraindications to POP: Pregnancy and breast cancer [2]
- IM injection every 12 weeks
- Higher progestogen dose → more reliable ovulation suppression than POP
- Advantage: does not rely on woman's memory [1]
- Side effects: weight gain, irregular bleeding/amenorrhoea, delayed return of fertility (up to 12 months), reduced bone mineral density (reversible)
- Subdermal rod inserted in upper arm
- Lasts 3 years
- One of the most effective methods (see efficacy tier chart) [2]
- Side effects: irregular bleeding, headache, mood changes
- Combined hormonal method (oestrogen + progestogen)
- Applied weekly for 3 weeks, patch-free 4th week
- Same contraindications as COC
- Advantage: weekly rather than daily compliance
IV. Intrauterine Devices (IUDs)
Two main types:
- Mechanism: Copper ions are toxic to sperm (spermicidal); also creates a sterile inflammatory reaction in the endometrium that impairs implantation
- Efficacy: Very high; failure rate < 1 per 100 women-years
- Duration: Up to 5–10 years depending on device
- Advantages: Non-hormonal; immediate effectiveness; suitable for women with contraindications to hormones; can be used for emergency contraception within 5 days of unprotected intercourse [1]
- Side effects: Heavier and more painful periods (especially first 3–6 months), risk of expulsion, very small perforation risk at insertion
- Recommended as barrier contraception alternative for women on enzyme-inducing AEDs [5]
- Mechanism: Local progestogen release → thickens cervical mucus, thins endometrium, partially inhibits ovulation
- Efficacy: Among the highest of all reversible methods
- Duration: 5 years (Mirena); 3 years (Kyleena/Jaydess)
- Advantages: Reduces menstrual blood loss (can treat menorrhagia); protective against endometrial hyperplasia; suitable for women who cannot use oestrogen
- Side effects: Initial irregular bleeding/spotting (usually settles), hormonal side effects (less than systemic methods)
Pregnancy can be prevented after unprotected coitus by either giving a hormonal preparation within 72–120 hours or inserting an intrauterine device within 5 days. Neither the hormonal nor intrauterine methods act as abortifacient. [1]
| Method | Regimen | Timeframe | Failure Rate | Notes |
|---|---|---|---|---|
| Yuzpe regimen | EE 100 mcg + levonorgestrel 0.5 mg (or norgestrel 1 mg) × 2 doses 12 hours apart [1] | Within 72 hours | ~2% | Significant nausea/vomiting |
| Levonorgestrel-only (RECOMMENDED) | Levonorgestrel 1.5 mg single dose [1] | Within 72 hours (some efficacy to 120h) | ~1–2% | Much less nausea than Yuzpe |
| Ulipristal acetate | 30 mg single dose [1] | Up to 120 hours after unprotected sex [1] | ~1–2% | Selective progesterone receptor modulator |
| Copper-bearing IUD | Insertion by trained clinician | Within 5 days of unprotected intercourse [1] | < 0.1% [1] | Can be continued for long-term contraception [1]; most effective EC method |
Mechanism: They act mainly by interfering with ovulation [1]
There are no known contraindications for use of hormonal emergency contraception, and no known teratogenic effects even if used inadvertently during pregnancy. [1]
It is not advised to be used repeatedly; instead a reliable regular birth control method should be adopted afterwards. [1]
Emergency Contraception - Must Know
The copper IUD is the most effective emergency contraceptive (failure rate < 0.1%) and has the added benefit of providing ongoing long-term contraception. Hormonal EC works primarily by delaying/inhibiting ovulation — it is NOT an abortifacient.
A permanent method of contraception, suitable for couples who do not want any more children. Couples need to be counselled carefully on the irreversibility and operative risks involved. [1]
| Feature | Male (Vasectomy) | Female (Tubal Ligation) |
|---|---|---|
| Procedure | Division/occlusion of vas deferens | Occlusion/division of fallopian tubes (laparoscopic clips, rings, or excision) |
| Anaesthesia | Local anaesthesia (minor procedure) | General/regional (more invasive) |
| Efficacy | Very high (failure ~0.1%) | Very high (failure ~0.5%) |
| Time to effect | NOT immediate — requires confirmation of azoospermia at ~3 months post-procedure (semen analysis) | Immediate |
| Reversibility | Technically possible but NOT guaranteed; counsel as permanent | Very difficult; IVF usually required |
| Complications | Haematoma, infection, chronic pain, sperm granuloma | Anaesthetic risk, bleeding, infection, damage to pelvic organs, ectopic pregnancy if failure |
Counselling points:
- Emphasise permanence — NOT easily reversible
- Discuss alternative LARC methods as an alternative if unsure
- Informed written consent required
- Young age, low parity, unstable relationship → higher regret rates → counsel carefully
| Tier | Methods | Typical-Use Failure Rate (pregnancies per 100 women in 1 year) |
|---|---|---|
| Most effective (< 1) | Implant, vasectomy, LNG-IUS, Cu-IUD, female sterilisation | < 1 |
| Very effective (1–9) | Injectable, COC pill, POP, patch, vaginal ring | 6–9 (typical) |
| Moderately effective (12–24) | Male condom, female condom, diaphragm/sponge, fertility awareness, withdrawal, spermicides | 12–28 |
Exam Tip
When asked "What is the most effective reversible contraceptive?", the answer is the subdermal implant (failure rate ~0.05%). LARC methods (implant, IUD) are the most effective reversible options because they are not user-dependent.
Special Situations
- Enzyme-inducing AEDs (carbamazepine, phenytoin, phenobarbitone) reduce efficacy of ALL hormonal contraception
- Advise barrier methods (condom) or copper IUD
- If hormonal method must be used → increase dosage
- Plan pregnancy with pre-conception folic acid 5 mg daily
- COC increases VTE risk → avoid in women with prior VTE, thrombophilia, or multiple risk factors
- OC pill use is a risk factor for economy class syndrome (VTE in long-haul flights) [6]
- OCP listed as precipitating factor to avoid in secondary VTE prevention [6]
- Progestogen-only methods are safer in this context
- COC (especially with anti-androgenic progestins) effective for acne
- Must balance benefits against ↑ CVS risk, ↑ VTE, ↑ breast cancer, ↑ cervical cancer risk [7]
- Avoid use of spermicides and diaphragms → use alternative contraceptive methods (spermicides disrupt vaginal flora and increase UTI risk) [8]
- MUST use contraception for females of childbearing potential due to severe teratogenicity [7]
- Two forms of contraception typically required; pregnancy test before starting and monthly during treatment
- Avoid COC (oestrogen suppresses lactation)
- POP, injectable, implant, and IUDs are safe during breastfeeding
- LAM can be used if criteria met (see above)
Structure for contraception counselling:
- Explore patient's needs: Why is she requesting contraception? Spacer vs. limiter?
- Previous contraceptive history: What has she tried? Any failures or side effects?
- Medical/obstetric/gynaecological history: Screen for contraindications
- Social/cultural background: Religious beliefs, partner involvement, motivation
- Present options: Tailored to her situation — explain mechanism, efficacy, side effects, pros/cons for each suitable method
- Shared decision: Let the patient choose
- Teach emergency contraception as a backup
- Arrange follow-up: Check satisfaction and compliance
Practical Cantonese phrases for OSCE:
- 避孕 (bei6 jan4) — contraception
- 你有冇用過避孕方法？ — Have you used any contraceptive methods before?
- 你有冇考慮過長效避孕方法，例如子宮環？ — Have you considered long-acting methods like an IUD?
- 呢個方法可能會有少少副作用... — This method may have some side effects...
Common Pitfalls
- Forgetting to screen for oestrogen contraindications before prescribing COC — always ask about smoking, age, migraine with aura, VTE history, hypertension.
- Not knowing that enzyme-inducing AEDs reduce hormonal contraception efficacy — a classic SAQ scenario.
- Confusing typical vs. perfect use failure rates — examiners want you to quote typical-use rates when counselling.
- Stating emergency contraception is an abortifacient — it is NOT; it works by inhibiting ovulation.
- Forgetting that copper IUD is the most effective emergency contraceptive (< 0.1% failure).
- Not counselling about STI protection — hormonal methods and IUDs do NOT protect against STIs; condoms still needed.
- Prescribing COC to a breastfeeding mother — oestrogen suppresses lactation; use progestogen-only or non-hormonal methods.
High Yield Summary
Contraceptive Methods — Key Exam Points:
- LARC methods (implant, IUD) are the most effective reversible contraceptives — not user-dependent.
- COC: oestrogen + progestogen; primary action = ovulation suppression. Contraindicated in smokers > 35, VTE history, migraine with aura, breast cancer, pregnancy.
- POP: progestogen only; lower efficacy than COC because ovulation not always suppressed. Safe for women with oestrogen contraindications.
- Natural methods: failure rate 24–40 per 100 women-years in typical use — least effective.
- Barrier methods: only condoms protect against STIs.
- Emergency contraception: levonorgestrel 1.5 mg single dose (recommended); copper IUD within 5 days (most effective, < 0.1% failure). Neither is abortifacient.
- Sterilisation: permanent — counsel on irreversibility; vasectomy requires semen analysis at 3 months to confirm azoospermia.
- Drug interactions: enzyme-inducing AEDs reduce all hormonal contraception efficacy → use barrier or copper IUD.
- Always tailor contraception to the individual: "Contraception is a choice, not a prescription!"
Active Recall - Contraceptive Methods
[1] Lecture slides: CFB (OG03) Fertility Regulation.pdf (all pages) [2] Lecture slides: Block C - The woman needs that drug: Oral contraceptives, Drugs affecting uterine motility.pdf (p5, p8) [3] Lecture slides: GC 160. The woman needs that drug Oral contraceptives Drugs affecting uterine motility.pdf (p23) [5] Senior notes: Maksim Medicine Notes.pdf (p259, Neurology — Pregnancy section) [6] Senior notes: Ryan Ho Haematology.pdf (p134, VTE secondary prevention) [7] Senior notes: Ryan Ho Rheumatology.pdf (p128, Acne — systemic therapy) [8] Senior notes: Ryan Ho Urogenital.pdf (p126, Recurrent cystitis)
Shoulder Dystocia
Shoulder dystocia is an obstetric emergency in which, after delivery of the fetal head, one or both fetal shoulders become impacted behind the maternal pubic symphysis, requiring additional maneuvers beyond gentle downward traction to complete delivery.
Adenomyosis
Adenomyosis is the presence of endometrial glands and stroma within the myometrium, causing diffuse uterine enlargement, dysmenorrhea, and menorrhagia.