CFB OG03 Fertility Regulation
Fertility regulation encompasses the clinical methods and physiological principles used to control reproductive capacity, including contraception, assisted reproduction, and management of the hormonal and cellular mechanisms governing gametogenesis, ovulation, and fertilization.
Fertility Regulation
Fertility regulation sits at the intersection of public health (population control) and individual autonomy (family planning). This lecture covers everything from preventing pregnancy to ending an unwanted one, and you need to know each method's mechanism, efficacy, side effects, contraindications, and counselling points. The examiners love this topic because it tests pharmacology, physiology, ethics, law, and clinical decision-making all at once.
Learning Objectives [1]:
- Describe the different contraceptive methods and discuss methods used to terminate pregnancy.
- List currently available methods of contraception (including sterilization) and describe their mechanisms of action, effectiveness, side effects, and medical eligibility criteria.
- Describe different methods of termination of pregnancy and its legal aspect.
- Counsel couples on contraceptive choice (including sterilization), taking into account risks and benefits.
- Counsel couples requesting termination of pregnancy, with special attention to psychosocial considerations.
Key framing from the lecture: "Contraception is a choice, not a prescription!" — The method must be tailored to the individual's needs, preferences, obstetric/gynae/medical history, motivation, and social/cultural background. [1]
How this fits into exams: Past papers have asked about emergency contraception choice (MCQ 2023 Q12), COC side effects (MCQ 2021 Q11), condom use for sex workers (MCQ 2022 Q14), and ethics of fertility regulation (SAQ 2020 Q12, SAQ 2022 Q10). Expect MCQs on mechanism/contraindication discriminators and SAQs on counselling/legal aspects.
I. Natural Methods
The principle is simple: a woman normally ovulates only once a month; the ovum lives ~24 hours after ovulation, whereas sperm is viable for up to 7 days in the female genital tract. [1] If you avoid intercourse during the fertile window, you avoid pregnancy.
The "fertile window" is therefore approximately Days 8–19 in a standard 28-day cycle (sperm deposited up to 7 days before ovulation can still fertilize the egg that lives 1 day after ovulation).
| Method | How It Works | Key Rules | Limitations |
|---|---|---|---|
| Standard Days Method | For cycles 26–32 days; abstain Days 8–19 | Should NOT use if > 2 cycles outside this range in past year | Rigid, only works for very regular cycles |
| Calendar/Rhythm | Abstain from (shortest cycle − 20) to (longest cycle − 10) based on past 12 months | Requires ≥12 months of cycle records | Many women have irregular cycles |
| BBT Method | Temperature rises ~0.5°C after ovulation (progesterone effect); abstain from Day 1 of menses until 3rd consecutive day of BBT elevation | Must measure at same time each morning before getting up | Only identifies ovulation retrospectively; illness/poor sleep affects BBT |
| Cervical Mucus Method | Mucus becomes thin, clear, stretchy, slippery around ovulation (oestrogen effect); abstain from first noting such mucus until 4 days after cessation | Requires training to assess mucus | Infections, medications can alter mucus |
| Sympto-thermal | Combines BBT + cervical mucus; abstain when mucus sticky/moist until 3rd day of BBT shift OR 4th day after mucus cessation, whichever is later | Most accurate natural method | Complex, requires commitment |
| Urine LH Test | OTC kits detect LH surge | NOT recommended for contraceptive purpose per lecture [1] | Only detects impending ovulation, not the full fertile window |
Why BBT works: After ovulation, the corpus luteum secretes progesterone, which acts on the hypothalamic thermoregulatory centre to raise basal temperature by ~0.5°C. This shift confirms ovulation has occurred. The limitation is that it only tells you ovulation has happened, not that it is about to happen, so it can't protect you from intercourse in the days leading up to ovulation.
Advantages: No religious objection, no equipment/medication, no physical side effects, both partners share responsibility.
Disadvantages: Highly dependent on motivation and commitment of both partners, requires learning period, failure rate 24–40 per 100 women-years in typical use [1], menstrual irregularity makes timing unreliable.
Not reliable because pre-ejaculatory fluid may already contain sperms. [1] The man must withdraw before ejaculation, but this requires perfect timing and self-control. Failure rates are high (around 20% in typical use).
Mechanism: Hyperprolactinaemia due to breastfeeding → anovulation. [1]
Efficacy: 98% effective IF all three criteria are met:
- Woman is fully breastfeeding
- Within 6 months postpartum
- Remaining amenorrhoeic
If ANY of the above criteria is breached, should NOT rely on LAM. [1]
Why it works from first principles: Suckling stimulates afferent nerve pathways from the nipple → hypothalamus → increased prolactin secretion → prolactin inhibits GnRH pulsatility → suppressed FSH/LH → no follicular development → anovulation. As breastfeeding frequency drops (supplementary feeds, solids at ~6 months), prolactin falls and ovulation resumes — often before menses return, which is why you can't rely on LAM once any criterion is breached.
These methods prevent conception by separating the ovum from the sperms either by mechanical means or by use of a spermicide. [1]
General advantages: No systemic side effects, immediate contraception, easily accessible.
General disadvantages: User-dependent, rely on couple's motivation/compliance, may cause discomfort or reduced sensation. For better effectiveness, consistent and correct use must be emphasized, and emergency contraception as a back-up method should be taught. [1]
| Method | Key Points | Failure Rate (typical use) |
|---|---|---|
| Male condom | Thin rubber sheath; also reduces HIV/STI transmission; breakage/slippage possible; latex allergy in some; should NOT use with oil-based lubricants | Up to 18 per 100 women-years |
| Female condom (Femidom®) | Inserted into vagina before penetration; under woman's control; allows continued intimacy in resolution phase; more expensive, hanging part may look awkward | ~21 per 100 women-years |
| Diaphragm | Thin plastic cap with elastic rim; various sizes; stretches across upper vagina; must be used with spermicidal jelly/cream | 6–20 per 100 women-years |
| Cervical cap | Worn over cervix; more tedious to use; now out of favour | Variable |
| Spermicides alone | Jelly, cream, foaming tablet, film, sponge; relatively high failure rate alone; messy; can cause vaginal irritation | High |
High-Yield Exam Point on Spermicides
Frequent use of nonoxynol-9 (the most commonly used spermicide) can increase HIV/STD transmission risk, probably by vaginal epithelial damage. It should NOT be used in those at high risk for HIV/STD infection. [1]
Spermicide-lubricated condoms do NOT provide additional protection against pregnancy or STD according to current evidence — use of spermicidal condoms is no longer encouraged. [1]
This is a classic exam discriminator: if a question asks about the BEST contraceptive for a sex worker or someone at high STI risk, do NOT pick "male condom with spermicide." Pick male condom alone. See 2022 MCQ Q14 where the answer is male condom (B), NOT condom + spermicide (C). [6]
III. Hormonal Contraceptives
Hormonal methods are either combined (oestrogen + progestogen) or progestogen-only. [1]
Forms available in Hong Kong [1]:
- Combined oral contraceptives (COCs)
- Progestogen-only pills (POPs)
- Progestogen-only injectable (Depo-Provera®)
- Combined injectable contraceptives (CICs, e.g. Cyclofem®)
- Transdermal contraceptive patch (e.g. Evra®)
Failure rate: < 0.5 per 100 women-years with perfect use; up to 9 per 100 women-years in typical use. [1]
A. Combined Oral Contraceptive (COC) Pills
Composition: Ethinylestradiol 20–35 mcg + a progestogen:
- 2nd generation: levonorgestrel
- 3rd generation: gestodene, desogestrel
- Newer: drospirenone
- Pills containing natural oestradiol have been recently introduced. [1]
Mechanism of action (triple mechanism):
- Inhibiting ovulation (primary mechanism — suppresses GnRH → ↓FSH/LH → no follicular development/LH surge)
- Thickens cervical mucus (progestogen effect — blocks sperm penetration)
- May reduce endometrial receptivity to the embryo (thinner endometrium less hospitable for implantation)
Why ovulation suppression works from first principles: The exogenous oestrogen and progestogen provide negative feedback to the hypothalamus and anterior pituitary, suppressing the pulsatile GnRH release needed to drive FSH (for follicle recruitment) and the mid-cycle LH surge (for ovulation). Without the LH surge, the dominant follicle never ruptures.
How to take: One tablet daily at about the same time, starting within first 5 days of cycle, typically 21 days of active pills followed by a 7-day pill-free interval (PFI); some packages include placebo pills during PFI; some newer preparations have shorter hormone-free breaks. [1]
COC carries non-contraceptive benefits: [1]
- Improving cycle regularity
- Reducing menstrual flow and dysmenorrhoea
- Reducing ovarian cysts and benign breast lesions
- Reducing pelvic inflammatory disease
- Protects against ovarian and endometrial cancers
Why protective against ovarian cancer? Suppression of ovulation means less "incessant ovulation" (each ovulation involves surface epithelial disruption and repair → opportunity for malignant transformation). Each year of COC use reduces ovarian cancer risk by ~5%, and protection persists for years after stopping.
Why protective against endometrial cancer? The progestogen component opposes oestrogen's proliferative effect on the endometrium, preventing the unopposed oestrogen stimulation that drives endometrial hyperplasia → cancer.
| Risk | Details |
|---|---|
| VTE (venous thromboembolism) | Increased risk; higher with 3rd-generation pills (gestodene, desogestrel) vs 2nd-generation (levonorgestrel); but absolute risk is small [1] |
| MI and stroke | Small increase in risk; modern low-dose pills generally safe in young healthy women without vascular risk factors [1] |
| Breast cancer | Minimal increase |
| Cervical cancer | Minimal increase |
| Minor side effects | Nausea, vomiting, dizziness, breast tenderness, fluid retention, weight gain, breakthrough bleeding — usually disappear after a few cycles [1] |
2021 MCQ Q11 — COC Side Effects
"Which is a recognised side effect of COC?" Answer: D. Increased risk of venous thromboembolism. [5]
The distractors were: increased risk of endometrial cancer (WRONG — COC is PROTECTIVE), increased infertility (WRONG — fertility usually returns in 1–3 months), increased ovarian cancer (WRONG — COC is PROTECTIVE). This is a high-yield discriminator.
After stopping COC, fertility usually returns in 1–3 months; there is no adverse effect on the fetus when COC is used immediately before or inadvertently during pregnancy. [1]
No need to "take a break" for long-term users; can be used till age 50 in the absence of contraindication. [1]
Although COC is a non-prescription drug in Hong Kong, medical assessment should be undertaken at the start to exclude contraindications, and annual review thereafter is recommended. [1]
More common contraindications include: [1]
- Full breastfeeding
- Non-breastfeeding women within 21 days postpartum (due to hypercoagulable state postpartum)
- Heavy smokers older than 35 years
- Co-existing risk factors for arterial cardiovascular disease
- Hypertension
- History of VTE / IHD / CVA / breast cancer / migraine (specifically migraine with aura for combined hormonal methods)
- Major surgery or prolonged immobilization
Why breastfeeding is a contraindication: Oestrogen suppresses prolactin and therefore reduces milk production. Postpartum women are also at heightened VTE risk, and adding exogenous oestrogen on top of the already hypercoagulable postpartum state is dangerous.
Why smoking + age > 35? Smoking causes endothelial damage and promotes a prothrombotic state. Oestrogen in COC independently increases clotting factor synthesis (especially fibrinogen, factors VII, X) and reduces antithrombin III. The combination of endothelial damage + procoagulant state in an older woman → unacceptably high risk of MI and stroke.
This is commonly tested. The lecture provides a specific protocol: [1]
| Scenario | Action |
|---|---|
| 1 pill missed | Take the missed pill as soon as remembered; continue remaining pills as scheduled |
| ≥2 pills missed | Take 1 pill ASAP; continue remaining pills at scheduled time; use additional protection for 7 days. If pills missed in Week 1 → consider emergency contraception (because the pill-free interval has effectively been extended, allowing follicular development). If pills missed in Week 3 → omit the pill-free interval and start a new pack right after the active pills (to prevent extending the hormone-free interval into a dangerously long gap). |
Why the Week 1 and Week 3 rules differ: In Week 1, missing pills means the PFI has been extended beyond 7 days — the hypothalamic-pituitary axis may have had enough time to "escape" suppression and recruit a follicle. Sperm from recent intercourse could still be viable → emergency contraception needed. In Week 3, the risk is that starting the PFI early creates the same extended gap problem, so you skip the PFI entirely.
Example: desogestrel. [1]
Mechanism: Cervical mucus thickening (all POPs); desogestrel also consistently inhibits ovulation. [1]
Advantages:
- Does not interfere with lactation → suitable for breastfeeding women [1]
- No oestrogen-related effects on blood pressure, haemostatic, and metabolic parameters [1]
Disadvantages:
- Menstrual irregularity: prolonged spotting, irregular short cycles, amenorrhoea [1]
- Regular pill-taking required: not later than 12 hours for desogestrel [1]
Fertility returns immediately upon discontinuation. [1]
Why POPs are safe in breastfeeding: They contain no oestrogen, so they don't suppress prolactin or reduce milk supply. Progestogens are present in breast milk in very small amounts but have no known adverse effects on the infant.
Mechanism: Suppresses ovulation + thickens cervical mucus. [1]
Failure rate: 0.1–0.6%. Very effective because they are user-independent once injected.
| Injectable | Type | Frequency | Key Points |
|---|---|---|---|
| Depo-Provera® | Progestogen-only depot (medroxyprogesterone acetate) | Every 3 months | Free from oestrogen-related effects; can be used in lactating women; reduces menstrual loss and dysmenorrhoea; BUT menstrual irregularity/hypo-/amenorrhoea may be unwanted. Long-term users have lower bone mass (usually recovers after discontinuation). Users should be educated on primary prevention of osteoporosis. Delay in return of fertility (½ to 1 year) after discontinuation. [1] |
| Cyclofem® | Combined injectable | Monthly | Better cycle control than Depo-Provera but bleeding problems may still occur. Action, adverse effects, and contraindications similar to COCs. [1] |
Why Depo-Provera affects bone: Chronic high-dose progestogen suppresses the HPO axis, leading to hypoestrogenism. Oestrogen is critical for maintaining bone mineral density (it inhibits osteoclast activity). Without adequate oestrogen, bone resorption exceeds formation → reduced BMD. This is reversible because once Depo-Provera is stopped, the HPO axis recovers and oestrogen levels normalize.
Why delayed fertility return with Depo-Provera? The depot formulation creates a large intramuscular reservoir of drug that is slowly released over months. Even after the injection interval, residual drug continues to suppress the HPO axis. It takes 6–12 months for complete clearance and restoration of ovulatory cycles.
Newer forms developed: [1]
- Combined contraceptive patch (e.g. Evra®): Applied and changed weekly for 3 consecutive weeks, then a patch-free week for withdrawal bleeding. Action similar to COC.
- Vaginal ring (e.g. NuvaRing®): Not yet available in HK
- Subdermal implant (e.g. Nexplanon®): Not yet available in HK. Action similar to POP.
Long-term safety data on adverse effects are still awaited. [1]
IV. Intrauterine Contraceptive Device (IUD)
Inert IUDs have been phased out now. [1]
Two types currently used:
- Copper-bearing IUD (e.g. Copper-T)
- Levonorgestrel-releasing IUD (LNG-IUD, Mirena®)
The exact mechanism of action of IUD is not known; it may work by: [1]
- Causing a foreign body reaction in the endometrium (sterile inflammatory response → hostile to implantation)
- Copper may inhibit sperm function and transport and reduce gamete viability (copper ions are toxic to sperm, impairing motility and acrosome reaction)
- LNG-IUD: local progestogen effect → thickens cervical mucus, thins endometrium, may partially suppress ovulation
| Feature | Copper IUD | LNG-IUD (Mirena®) |
|---|---|---|
| Failure rate | < 1 per 100 women-years | < 1 per 100 women-years |
| Duration | 5–10 years | 5 years |
| Systemic effects | None | Local progestogen; minimal systemic |
The device can be inserted and removed by a simple office procedure. [1]
Highly effective, long-acting, reversible, and user-independent. Effective immediately after insertion. No systemic side effect (copper IUD). LNG-IUD offers additional non-contraceptive benefit of improving menorrhagia and dysmenorrhoea. [1]
| Effect | Copper IUD | LNG-IUD |
|---|---|---|
| Menstrual change | Menorrhagia or dysmenorrhoea | Prolonged spotting first 3–6 months; reduced/absent menstruation subsequently |
| Other | Pain, vaginal bleeding, increased vaginal discharge | Same |
| Infection risk | Increased in the 20 days after insertion; long-term risk beyond 3 weeks is very low | Same |
| Perforation | Traumatic perforation of uterus at time of insertion (rare but serious) | Same |
| Expulsion/translocation | Occasionally happens | Same |
Risk minimized by proper pre-insertion screening and aseptic technique. [1]
Absolute contraindications: [1]
- Known or suspected pregnancy
- Current infection of the genital tract
- Undiagnosed vaginal bleeding
- Uterine abnormalities with endometrial cavity distortion
- Current gestational trophoblastic neoplasia
Relative contraindications: [1]
- Increased risk of STD
- Severe thrombocytopenia (risk of heavy bleeding)
- Beyond 40 hours but within 4 days postpartum (uterus is soft and involution incomplete → ↑perforation risk)
LNG-IUD should NOT be used in women with breast cancer. [1] (Because progestogens may stimulate hormone-receptor-positive breast cancer cells.)
V. Emergency Contraception (Postcoital Contraception)
Emergency contraception is a back-up for contraceptive failure or after an incident of rape. [1]
Critical Principle
Neither the hormonal nor intrauterine methods of emergency contraception act as an abortifacient. [1] They work by preventing or delaying ovulation (hormonal) or preventing implantation (copper IUD). They do NOT disrupt an established pregnancy.
| Regimen | Dose | Timing | Notes |
|---|---|---|---|
| Yuzpe regimen | EE 100 mcg + LNG 0.5 mg (or norgestrel 1 mg), 2 doses 12 hours apart | Within 72h | Nausea/vomiting common (oestrogen effect); now largely superseded |
| Levonorgestrel-only | 1.5 mg single dose | Within 72h (recommended regimen) | Much less nausea than Yuzpe; preferred first-line hormonal EC |
| Ulipristal | 30 mg single dose | Up to 120 hours (5 days) after unprotected sex | Selective progesterone receptor modulator; delays ovulation even after LH surge has begun |
Mechanism: Act mainly by interfering with ovulation. [1]
Failure rate: ~1–2%. [1]
No known contraindications for use of hormonal emergency contraception; no known teratogenic effects even if used inadvertently during pregnancy. [1]
Not advised to be used repeatedly; a reliable regular birth control method should be adopted afterwards. [1]
Copper-bearing IUD can be used within 5 days of unprotected intercourse. [1]
Mechanism: May act by preventing implantation (the sterile inflammatory reaction and copper toxicity to sperm/embryo) [1].
Failure rate: < 0.1% — the most effective form of emergency contraception. [1]
It can be continued for long-term contraception. [1] — This is a major advantage: one intervention solves both the acute problem and future contraceptive needs.
2023 MCQ Q12 — Emergency Contraception
Stem: 40-year-old woman, completed family (3 children), no further fertility wish. Condom slipped last night. What is the MOST APPROPRIATE treatment?
Answer: A. Copper intrauterine device. [7]
Why? She has completed her family → she needs long-term contraception anyway. The copper IUD is the most effective EC method (failure rate < 0.1% vs 1–2% for hormonal), AND it provides ongoing contraception for 5–10 years. The question specifically says "no further fertility wish," which is the examiners' clue to pick IUD. If this were a teenager not wanting IUD insertion, levonorgestrel would be the first-line hormonal option.
VI. Sterilisation
A permanent method of contraception, suitable for couples who do not want any more children. [1]
Couples need to be counselled carefully on the irreversibility and operative risks involved. [1]
Factors that may influence later regret: [1]
- Young age ( < 30 years)
- Being single or married for < 5 years
- Not having children of both sexes
- Unstable marital relationship
- Coercion from others to have the operation
- Objection from spouse
- Recent life crisis (e.g. after pregnancy termination or delivery, separation or divorce, death of spouse)
These are counselling points you must be able to list in an SAQ or OSCE. The reason they matter: sterilisation reversal is technically difficult, expensive, and has variable success rates. A decision made under duress or emotional distress is more likely to be regretted.
Performed via mini-laparotomy or laparoscopy. [1]
Fallopian tube occluded by: ligation, application of clips or rings, diathermy, or resection. [1]
Failure rate: 2–5 per 1000 lifetime risk. [1]
Risks: operative complications (visceral damage, bleeding, wound complications) and increased risk of ectopic pregnancy in case of failure. [1]
Why ectopic risk increases if sterilisation fails: If a partial recanalisation occurs, the tubal lumen may be narrowed enough to allow sperm through but too narrow for the larger fertilised ovum to pass back to the uterus → tubal ectopic pregnancy. This is an important counselling point.
Simple operation performed under local anaesthesia as day surgery. [1]
Failure rate: 0.5 per 1000 lifetime risk. [1] (Lower than female sterilisation — important comparison.)
NOT immediately effective — a reliable birth control method must be used until at least 2 negative semen tests consecutively. [1]
Why not immediately effective? Sperm already present in the vas deferens distal to the vasectomy site can persist for weeks to months. Typically, it takes ~20 ejaculations or ~3 months to clear residual sperm. The two consecutive negative semen analyses confirm azoospermia.
VII. Termination of Pregnancy (TOP)
A pregnancy can be terminated under the circumstance if two registered practitioners are of the opinion, formed in good faith, that: [1]
(a) the continuance of the pregnancy would involve risk to the life of the pregnant woman or of injury to the physical or mental health of the pregnant woman, greater than if the pregnancy were terminated, OR
(b) there is substantial risk that if the child were born, it would suffer from such physical or mental abnormality as to be seriously handicapped.
Any treatment for termination of pregnancy must be carried out in a hospital approved in the Government Gazette or the Family Planning Association of Hong Kong. [1]
Legal Requirements for TOP in HK — Exam Must-Know
You need to remember THREE things:
- Two registered practitioners must agree
- Two grounds: maternal health/life risk OR fetal abnormality
- Approved venue only: Government Gazette hospital or FPAHK
There is no gestational age limit specified in the HK Offences Against the Person Ordinance (Cap 212, Section 47A), unlike the UK (which generally limits to 24 weeks). However, practically, second-trimester TOP is more complex and risky.
The lecture emphasises a specific counselling framework: [1]
Attitude:
- Be understanding, sympathetic, and non-judgemental
- Respect client's informed decision
- Do NOT imply irresponsible or immoral acts or induce guilt
Content of counselling:
- Reason(s) for requesting TOP
- Contraceptive history: reason for contraceptive failure, plan for future contraception
- Options: continuation of pregnancy, adoption, termination of pregnancy
- Assess psychosocial issues
- Explain method and risks of abortion procedure
Assessment:
- Medical, drug, and allergy history
- Rhesus type (important — if Rh-negative, need anti-D prophylaxis to prevent Rh isoimmunisation in future pregnancies)
- Ascertain dating by history, examination ± ultrasound
- Screen or empirical antibiotic prophylaxis for STIs (to prevent ascending infection during the procedure)
| Method | Details | Advantages | Disadvantages |
|---|---|---|---|
| Medical abortion | Mifepristone 200 mg PO, followed by Misoprostol (vaginal, sublingual, or buccal route) 1–2 days later | Less invasive; avoids risks of anaesthesia and surgical procedure | May take hours–days; cramping; bleeding |
| Surgical abortion | Suction evacuation | Quicker in achieving complete abortion | Requires anaesthesia; risks of perforation, cervical trauma |
Complete abortion rate for medical method: > 95%. [1]
How mifepristone + misoprostol works:
- Mifepristone is an anti-progestogen (progesterone receptor antagonist). Progesterone is essential for maintaining the decidua. Blocking progesterone → decidual necrosis → detachment of conceptus. It also sensitises the myometrium to prostaglandins and softens the cervix.
- Misoprostol is a prostaglandin E1 analogue. It stimulates myometrial contractions and cervical dilatation → expulsion of products of conception.
Dilatation and evacuation (D&E) can be safe and effective if performed by experienced personnel. [1]
However, the medical method is more commonly adopted for second-trimester abortions. [1]
Regimen: Misoprostol 400 mcg PV Q3H (up to 5 times/day). [1]
Misoprostol is a prostaglandin which stimulates uterine contraction and cervical dilatation → expulsion of conceptus. [1]
Complications: infection, bleeding, failed or incomplete abortion. Suction evacuation may be needed for retained products or heavy bleeding. [1]
Complete abortion rate within 24 hours: 80–90%. [1]
The client's ongoing contraceptive practice should be reinforced. [1]
IUD can be inserted immediately after surgical abortion or second-trimester abortion. [1]
Hormonal contraceptives can be started right after the abortion. [1]
During follow-up: assess for complications, contraceptive compliance and problems, and be aware of emotional or social problems. [1]
| Method | Mechanism | Failure Rate (typical use) | Advantages | Disadvantages | Key Contraindications |
|---|---|---|---|---|---|
| Natural methods | Periodic abstinence around ovulation | 24–40/100 WY | No side effects, no religious objection | Requires motivation, learning, regular cycles | None medical; not for irregular cycles |
| Male condom | Barrier | 18/100 WY | STI protection, accessible | Breakage, reduced sensation, latex allergy | Latex allergy |
| COC | Ovulation suppression + cervical mucus + endometrium | 9/100 WY | Non-coital, ↓dysmenorrhoea, ↓cancer risk | VTE risk, daily pill taking | VTE hx, smoking > 35, breastfeeding, migraine with aura |
| POP (desogestrel) | Cervical mucus + ovulation inhibition | ~9/100 WY | Safe in breastfeeding, no oestrogen effects | Menstrual irregularity, strict timing | Few absolute |
| Depo-Provera® | Ovulation suppression + cervical mucus | 0.1–0.6% | Q3 months, private, ↓menorrhagia | ↓BMD, delayed fertility return, menstrual irregularity | Osteoporosis risk factors (relative) |
| Copper IUD | Foreign body reaction + copper spermicidal | < 1/100 WY | 5–10 years, user-independent | Menorrhagia, dysmenorrhoea, perforation risk | Pregnancy, genital infection, cavity distortion |
| LNG-IUD (Mirena®) | Local progestogen + IUD effect | < 1/100 WY | 5 years, ↓menorrhagia, ↓dysmenorrhoea | Initial spotting, amenorrhoea | Breast cancer, as for copper IUD |
| EC – Levonorgestrel | Delays ovulation | ~1–2% | OTC, single dose | Not for regular use | None absolute |
| EC – Copper IUD | Prevents implantation | < 0.1% | Most effective EC; continues as LARC | Requires insertion procedure | As for copper IUD |
| Female sterilisation | Tubal occlusion | 2–5/1000 lifetime | Permanent | Irreversible, surgical risks, ectopic if failure | Desire for future children |
| Vasectomy | Vas deferens interruption | 0.5/1000 lifetime | Simple, local anaesthesia, lowest failure | Irreversible, not immediately effective | Desire for future children |
IX. Integration with Related Material
When counselling about contraception, always consider the couple's fertility intentions. The GC 117 lecture on infertility reminds us that sperm concentration threshold for efficacy in male hormonal contraception is 3 million/mL [2] — a concept tested in research but not clinical practice. More importantly, knowledge of contraceptive mechanisms helps you understand how to reverse infertility: if COC suppresses ovulation, then ovulation induction (with letrozole, clomiphene, or gonadotrophins) is the logical treatment for anovulatory infertility.
The GC 114 lecture notes that in PCOS, COC pills are used for menstrual regulation and prevention of endometrial hyperplasia/cancer [3]. This is one of the non-contraceptive therapeutic uses of COC that examiners love.
GC 160 emphasises that "family planning care should not have a singular focus of preventing unintended pregnancy" — it should support people in making informed decisions aligned with their preferences and reproductive goals [8]. This is the modern framing of reproductive autonomy.
HSG is used to assess fallopian tube patency and uterine anatomy in infertility investigation. Patent fallopian tubes show free spill of contrast into the peritoneal cavity [9]. This was tested in 2018 Rotation 3 MCQ Q23 — answer is HSG. Important to understand that tubal patency assessment is part of the infertility workup after failed natural conception, and is relevant when counselling about sterilisation reversal.
X. Likely Exam Questions
-
A 26-year-old G0P0 woman wants contraception. She has no medical history and doesn't smoke. Which is a recognised side effect of COC?
- Answer: Increased risk of VTE (NOT endometrial cancer, NOT ovarian cancer, NOT infertility) [5]
-
A 25-year-old sex worker wants contraception and STI protection. Best option?
- Answer: Male condom (NOT condom + spermicide — nonoxynol-9 increases HIV risk with frequent use) [6]
-
A 40-year-old woman, completed family, condom failure last night. Most appropriate EC?
- Answer: Copper IUD (most effective EC + ongoing LARC for someone with no further fertility wish) [7]
-
Which emergency contraceptive can be used up to 120 hours after unprotected intercourse?
- Answer: Ulipristal 30 mg (levonorgestrel only approved to 72h; copper IUD within 5 days)
-
A breastfeeding mother 3 months postpartum wants hormonal contraception. Which is most appropriate?
- Answer: POP (desogestrel) — COC is contraindicated in breastfeeding
-
List 4 contraindications to COC. (4 marks)
- Breastfeeding; smoker > 35; hx VTE; hx breast cancer; migraine with aura; HTN; < 21 days postpartum (any 4)
-
Describe the management of ≥2 missed COC pills in Week 3. (3 marks)
- Take 1 missed pill ASAP; continue remaining pills; use additional protection for 7 days; skip the pill-free interval and start new pack immediately after current active pills
-
What are the legal requirements for TOP in Hong Kong? (3 marks)
- Two registered practitioners agree in good faith; ground is risk to maternal health/life or substantial risk of serious fetal handicap; must be performed at Government Gazette-approved hospital or FPAHK
-
List 4 factors that increase the risk of regret after sterilisation. (4 marks)
- Age < 30; single or married < 5 years; no children of both sexes; unstable marital relationship; coercion; spouse objection; recent life crisis
-
What are the 3 criteria for Lactational Amenorrhoea Method to be effective? (3 marks)
- Fully breastfeeding; within 6 months postpartum; amenorrhoeic (all three must be met)
| Trap | Why Students Get It Wrong | Correct Answer |
|---|---|---|
| "COC increases endometrial cancer" | COC actually PROTECTS against endometrial cancer (progestogen opposes oestrogen) | COC ↓ endometrial cancer |
| "COC increases ovarian cancer" | COC PROTECTS against ovarian cancer (suppresses incessant ovulation) | COC ↓ ovarian cancer |
| "COC causes infertility" | Fertility returns in 1–3 months after stopping | No long-term infertility |
| "Spermicide + condom is better" | Nonoxynol-9 damages vaginal epithelium → ↑ STI risk; no additional protection | Condom alone is sufficient |
| "Vasectomy is immediately effective" | Residual sperm in distal vas; need 2 negative semen analyses | NOT immediately effective |
| "Copper IUD is contraindicated for EC" | Copper IUD within 5 days is the MOST effective EC | Copper IUD is first-line EC for completed families |
| "LNG-IUD for emergency contraception" | Only COPPER IUD can be used for EC; LNG-IUD is NOT approved for this purpose | Copper IUD only |
| "Mifepristone is a prostaglandin" | Mifepristone is an anti-progestogen; MISOPROSTOL is the prostaglandin | Know the difference |
| "Depo-Provera: fertility returns immediately" | Delayed return of fertility (6–12 months) due to depot formulation | Unlike POP where fertility returns immediately |
High Yield Summary
Contraception is a choice, not a prescription — tailor to individual. Know every method's mechanism, efficacy, side effects, and contraindications.
COC: Triple mechanism (suppress ovulation, thicken mucus, thin endometrium). PROTECTS against ovarian and endometrial cancer. Key risks: VTE (higher with 3rd-gen pills), MI/stroke in smokers > 35. Contraindicated in breastfeeding, VTE hx, migraine with aura, smoking > 35, HTN.
POP: Safe in breastfeeding. Desogestrel also inhibits ovulation. Strict timing (≤12h late).
Depo-Provera: Q3 months IM. ↓BMD (reversible). Delayed fertility return (6–12 months).
IUD: Copper (5–10 years) or LNG-IUD Mirena (5 years). Most effective reversible methods (< 1/100 WY). Copper IUD also best emergency contraceptive (< 0.1% failure within 5 days).
Emergency Contraception: Levonorgestrel 1.5 mg single dose (within 72h, recommended hormonal). Ulipristal 30 mg (up to 120h). Copper IUD (within 5 days, most effective, can continue as LARC). None are abortifacients.
Sterilisation: Female (laparoscopy/mini-lap, 2–5/1000 lifetime failure) vs Male (vasectomy, 0.5/1000, simpler but NOT immediate). Counsel on irreversibility and regret factors.
TOP in HK: Two doctors, two grounds (maternal risk or fetal abnormality), approved venue only. First trimester: mifepristone + misoprostol (medical, > 95% success) or suction evacuation (surgical). Second trimester: misoprostol 400 mcg PV Q3H (80–90% within 24h).
Post-abortion: Start contraception immediately. IUD can be inserted right after surgical/2nd-trimester TOP. Hormonal methods can start same day.
Active Recall - Fertility Regulation
[1] Lecture slides: CFB (OG03) Fertility Regulation.pdf (all pages) [2] Lecture slides: GC 117. I want to have a baby male and female infertility.pdf (p18) [3] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p28) [4] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (p19) [5] Past papers: 2021 Fourth Summative Assessment MCQ.pdf (Q11) [6] Past papers: 2022 Fourth Summative MCQ.pdf (Q14) [7] Past papers: 2023 Fourth Summative MCQ.pdf (Q12) [8] Lecture slides: GC 160. The woman needs that drug Oral contraceptives Drugs affecting uterine motility.pdf (p23) [9] Senior notes: Ryan Ho Diagnostic Radiology.pdf (p23) [10] Past papers: 2020 Fourth Summative SAQ.pdf (Q12) [11] Past papers: 2022 Fourth Summative SAQ.pdf (Q10) [12] Past papers: 2025 Fourth Summative MCQ.pdf (Q8) [13] Lecture slides: MBBS_SRH_2025.8.10.pdf (p23)
CFB MED07 Examination Of The Abdomen
A systematic clinical assessment of the abdomen involving inspection, auscultation, percussion, and palpation to identify organomegaly, tenderness, masses, fluid, or other abdominal pathology.
CFB MED01 History Taking And General Examination
History taking and general examination is the foundational clinical process of systematically gathering a patient's medical history through structured interviewing and performing an overall physical assessment to guide diagnosis and management.