Contraception - combined hormonal methods
Exam Tips
- Mechanism: CHC primarily prevents ovulation via LH/FSH suppression; mucus/endometrial effects are secondary.
- UK first-line COC in many patients: monophasic ~30 mcg ethinylestradiol with levonorgestrel or norethisterone.
- Start rules: day 1 start gives immediate cover; later starts usually need 7 days of condoms (9 days for Qlaira).
- Postpartum: avoid CHC in breastfeeding women before 6 weeks; consider VTE risk carefully in all postpartum starts.
- After oral EC: start immediately after levonorgestrel EC, but wait 5 days after ulipristal before starting CHC.
- Use ACHES red flags in OSCE counselling to demonstrate safety-netting competence.
Definition
Combined hormonal contraception (CHC) includes the combined oral contraceptive pill, transdermal patch, and vaginal ring, each containing an oestrogen plus a progestogen to prevent pregnancy. In UK practice, CHC is a highly effective reversible method used from menarche to perimenopausal years when medically eligible, with regimen choice tailored to bleeding preference, adherence, comorbidity, and thrombotic risk.
Pathophysiology
CHC mainly works by suppressing the hypothalamic-pituitary-ovarian axis: exogenous oestrogen and progestogen reduce FSH/LH release, preventing the LH surge and ovulation. Progestogen also thickens cervical mucus and impairs sperm penetration; endometrial receptivity and tubal transport are altered, further reducing fertilization/implantation probability. The traditional 21/7 schedule triggers a hormone-withdrawal bleed rather than true menstruation; extended/continuous regimens reduce hormone-free intervals and can reduce hormone-withdrawal symptoms and escape ovulation risk. See Figure: HPO axis feedback suppression in a standard reproductive endocrinology diagram.
Risk Factors
- Venous thromboembolism risk factors (personal/family VTE history, thrombophilia, immobility, obesity, smoking, increasing age)
- Migraine with aura (stroke risk increases with oestrogen-containing methods)
- Postpartum state, especially early postpartum and with additional VTE risk factors
- Cardiovascular risk factors (hypertension, diabetes with vascular disease, significant dyslipidaemia)
- Smoking age 35 years or over
- Current or past breast cancer or severe liver disease (method-specific contraindication)
- Drug interactions reducing efficacy (enzyme-inducing antiepileptics, rifampicin/rifabutin, St John's wort)
- Poor adherence with daily oral dosing (higher user-failure risk)
Clinical Features
Symptoms
- Usually asymptomatic when well tolerated
- Common early adverse effects: nausea, breast tenderness, breakthrough bleeding/spotting, headaches
- Cycle-control goals: lighter/less painful withdrawal bleeds or fewer bleeds on tailored regimens
- Warning symptoms requiring urgent assessment (ACHES): severe abdominal pain, chest pain/dyspnoea, severe headache/neurological symptoms, eye/visual symptoms, severe leg pain/swelling
Signs
- Baseline blood pressure and BMI/weight recorded before initiation
- No routine pelvic or breast examination required solely to start CHC
- Raised blood pressure on follow-up may require method change
- Signs of VTE or stroke are red flags and mandate immediate cessation and urgent evaluation
Investigations
Management
Lifestyle Modifications
- Shared decision-making on method (pill vs patch vs ring), bleeding pattern preference, and adherence capacity
- Counsel on perfect vs typical use effectiveness and missed-method actions
- Use condoms for STI protection (CHC does not protect against STIs)
- Smoking cessation and cardiovascular risk reduction advice
- Safety-net counselling for VTE/stroke symptoms and when to seek urgent care
- Provide up to 12 months' supply where appropriate to reduce gaps in use
Pharmacological Treatment
Combined oral contraceptive (first-line monophasic)
- Ethinylestradiol 30 micrograms + levonorgestrel 150 micrograms tablet once daily (e. g, 21 active tablets then 7-day break, or tailored extended/continuous regimen)
- Ethinylestradiol 30-35 micrograms + norethisterone 0.5-1 mg tablet once daily (monophasic option)
In UK guidance, monophasic ~30 mcg ethinylestradiol with levonorgestrel or norethisterone is a common first choice. Start day 1 cycle for immediate cover; if started later, use condoms for 7 days (9 days for estradiol valerate/dienogest formulation such as Qlaira). Contraindications/safety: migraine with aura, current/past VTE or thrombophilia, severe hypertension, smoking >=35 years with significant smoking, major surgery with prolonged immobility, severe liver disease, current breast cancer.
Combined transdermal patch
- Norelgestromin 203 micrograms/24 hours + ethinylestradiol 33.9 micrograms/24 hours patch, changed weekly for 3 weeks then 1 patch-free week
Useful when daily pill adherence is difficult. Same oestrogen-related contraindications as COC. Check patch adherence and skin issues; if patch detaches or change is delayed, follow missed patch rules and use backup contraception as indicated.
Combined vaginal ring
- Etonogestrel 11.7 mg + ethinylestradiol 2.7 mg vaginal ring (releases about 120/15 micrograms daily), keep in place for 3 weeks then 1 ring-free week
Monthly user action may improve adherence compared with daily pills. Same contraindications as other CHC. If ring removed/expelled for prolonged periods, backup contraception is required per missed ring guidance.
Quick-start and post-emergency contraception timing
- After levonorgestrel emergency contraception: start CHC immediately, use condoms for 7 days (9 days for Qlaira)
- After ulipristal acetate emergency contraception: delay CHC start for 5 days, then use condoms for 7 days after starting
This avoids pharmacodynamic interaction that can reduce ulipristal efficacy. If vomiting occurs within about 3 hours of oral pill intake, repeat pill and use missed-pill guidance.
Complications
- Venous thromboembolism (DVT/PE)
- Ischaemic stroke (especially with migraine with aura or additional risk factors)
- Myocardial infarction in high-risk users
- Hypertension or worsening blood pressure control
- Breakthrough bleeding leading to discontinuation/non-adherence
- Contraceptive failure from missed doses or drug interactions
Prognosis
For medically eligible users, CHC is safe, effective, and rapidly reversible, with fertility typically returning quickly after cessation. Continuation and success depend on method fit, adherence support, and proactive management of bleeding side effects and risk factors.
Sources & References
✅NICE Guidelines(1)
📖Textbook References(4)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1701)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1709, 1710)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1710)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 80)[context]