Sex Hormones and Contraceptives
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Direct answer
Combined oral contraceptives pair ethinylestradiol 30 µg with a progestin such as levonorgestrel 150 µg in a 21-day, 7-day pill-free pattern (or 24/4), working mainly by suppressing ovulation through gonadotrophin inhibition; their absolute contraindications — migraine with aura, prior venous thromboembolism, breast cancer, uncontrolled hypertension, smoking over age 35, and the postpartum window — decide more exam answers than their mechanisms do. Progestin-only methods span the desogestrel 75 µg mini-pill, depot medroxyprogesterone 150 mg every three months (reversible bone-density reduction, delayed return of fertility), the etonogestrel implant and the levonorgestrel intrauterine system for heavy menstrual bleeding. Emergency contraception is levonorgestrel 1.5 mg within 72 hours (earlier is better), ulipristal 30 mg within 120 hours, or a copper IUD up to five days after intercourse — the most effective option. India's non-hormonal oddity is centchroman (ormeloxifene) 30 mg twice weekly for 12 weeks then weekly, a SERM developed by CDRI and distributed free as Chhaya in the national programme.
What you must remember
- Mechanism of COC: suppression of FSH/LH (no ovulation), plus endometrial thinning and cervical mucus thickening; typical-use failure around 8 per cent versus under 1 per cent for implants and IUDs.
- COC absolute contraindications (WHO category 4): migraine with aura, history of VTE or thrombophilia, breast cancer, severe liver disease, uncontrolled hypertension, smoker aged 35+, and the first 21 days postpartum.
- COC risks and side effects: VTE risk highest in the first year; breakthrough bleeding in the first three months; blood pressure checked annually; the "pill danger signs" mnemonic ACHES (abdominal pain, chest pain, headache, eye problems, severe leg pain) is examinable counselling.
- DMPA 150 mg IM every 3 months (Antara in the Indian programme): irregular bleeding then amenorrhoea; reversible bone mineral reduction; fertility return delayed up to a year — safe in breastfeeding and largely contraindication-free.
- LNG-IUS 52 mg (5 years): first-line drug treatment for heavy menstrual bleeding — reduces blood loss dramatically — and widely used in adenomyosis and dysmenorrhoea.
- Emergency contraception: levonorgestrel 1.5 mg single dose within 72 h (does not terminate an existing pregnancy, no embryotoxicity); copper IUD within 5 days is the most effective emergency method.
- Drug interaction that fails the pill: rifampicin and other enzyme inducers (antitubercular therapy is the Indian classic) — advise barrier cover or switch method; the same logic applies to certain antiepileptics.
- Centchroman 30 mg: non-steroidal SERM; twice weekly for 12 weeks then once weekly; delayed menses is the common complaint; the national programme brand is Chhaya.
A contraceptive counselling session, step by step
A 27-year-old postpartum mother at six weeks, breastfeeding, wants spacing. Screen first: her blood pressure, migraine history (without aura), smoking and VTE history clear her for most methods. Breastfeeding tilts the balance toward progestin-only options in the early weeks — DMPA 150 mg or the desogestrel mini-pill — since combined oestrogen can reduce milk volume. Discuss her plan honestly: DMPA delays fertility return; if she wants another child within a year, the mini-pill or an IUD suits better. Offer the copper IUD 380A immediately as a 10-year method she can forget, and the national programme supplies it free. Counselling includes the return-to-fertility facts and bleeding patterns for each method — most FMGE contraception stems are counselling stems in disguise.
Now the missed-pill question, asked in every exam season: one missed combined pill taken within 24 hours needs no extra precaution; two or more missed pills require taking the most recent pill, using condoms for seven days, and emergency contraception if the gap was in the pill-free run-up. The interaction question follows: starting antitubercular therapy with rifampicin — barrier protection for the duration plus a complementary method, because enzyme induction strips the pill's efficacy.
Where students slip
Candidates rank methods by popularity instead of eligibility — the WHO medical eligibility logic (category 4 means "no") is what the options actually test. The migraine-with-aura contraindication (ischaemic stroke risk) versus migraine without aura (acceptable) is the classic discriminator. Second, emergency contraception confusion: levonorgestrel within 72 hours prevents ovulation, it does not abort — a stem describing its "teratogenic risk" is testing the absence of that risk. Third, DMPA's bone story is reversible and not an absolute contraindication at any age, despite the boxed-warning history in some markets. Finally, centchroman's twice-weekly-then-weekly schedule is a pure Indian-programme detail that separates the NLEM-aware candidate from the rest.
Frequently asked questions
Which contraceptive is contraindicated in migraine with aura?
Combined hormonal contraception, because oestrogen multiplies ischaemic stroke risk; progestin-only methods remain eligible.
What is the schedule of centchroman?
30 mg orally twice weekly for the first 12 weeks, then once weekly — a non-hormonal SERM contraceptive developed in India and provided free under the national programme as Chhaya.
Which emergency contraceptive works up to five days?
The copper IUD (most effective) and ulipristal 30 mg; levonorgestrel 1.5 mg is licensed to 72 hours with best efficacy when taken earliest.
Why does rifampicin cause contraceptive failure?
It induces hepatic CYP enzymes, accelerating oestrogen and progestin metabolism — barrier contraception or a non-hormonal method is advised during therapy.
Which hormonal method treats heavy menstrual bleeding?
The levonorgestrel-releasing intrauterine system, which markedly reduces menstrual loss while providing contraception for five years.