Describe the classification of methods, with their mechanism, advantages and limitations of contraception.

Definition

Contraception is the voluntary prevention of pregnancy by temporary (reversible) or permanent (irreversible) methods, enabling couples to plan the number and spacing of their children.

Methods of Contraception

Classification

A. Temporary (spacing) methods

• Barrier — male/female condom and diaphragm (with spermicide); prevent sperm–ovum meeting and also guard against sexually-transmitted infection, but have a higher failure rate.
• Hormonal — combined oral pills (oestrogen + progestin) acting mainly by inhibiting ovulation; progestin-only pills, injectable DMPA, subdermal implants, the vaginal ring and the patch. Highly effective; cautions include thromboembolism (oestrogen) and irregular bleeding (progestin).
• Intra-uterine devices — copper IUCD (Cu-T 380A) (a foreign-body and spermicidal copper effect) and the levonorgestrel-releasing IUS (Mirena); long-acting and reversible.
• Natural / fertility-awareness — calendar (rhythm), basal temperature and cervical-mucus methods, withdrawal and lactational amenorrhoea; no side-effects but less reliable.
• Emergency contraception — after unprotected intercourse (see short note).

B. Permanent (terminal) methods

• Female sterilisation — tubal ligation (laparoscopic/minilap, post-partum), occluding the fallopian tubes.
• Male sterilisation — vasectomy (no-scalpel), interrupting the vas deferens; simpler and safer than female sterilisation but requires confirmation of azoospermia.

Measuring Effectiveness

Efficacy is expressed by the Pearl index — the number of accidental pregnancies per 100 woman-years of exposure; the lower the index, the more effective the method. Long-acting reversible methods (IUCD, implant) and sterilisation have the lowest indices, while barrier and natural methods have the highest.

Newer / Non-hormonal Options

Centchroman (ormeloxifene, "Saheli") is a non-steroidal once-weekly oral contraceptive (a selective oestrogen-receptor modulator) suited to lactating women; the levonorgestrel-IUS additionally reduces menstrual loss.

The Ideal Contraceptive

Should be safe, effective, acceptable, reversible (for spacing), cheap, easy to use and free of side-effects. No single method is ideal; the choice is individualised to the couple's age, parity, family plans, health and preference.

Selection (counselling Points)

• Spacing the family — barrier, hormonal or IUCD.
• Completed family — IUCD or sterilisation.
• Postpartum / lactating — progestin-only methods, IUCD (PPIUCD) or lactational amenorrhoea.
• Avoid oestrogen in smokers > 35 years and those with thromboembolic/cardiovascular risk.

Contraceptive methods, ranked by effectiveness: permanent methods (tubal ligation, vasectomy) are the most effective; long-acting reversible contraceptives (copper IUCD, LNG-IUS, implants) are almost as effective because they remove user error; hormonal methods (the combined pill, progestogen-only pill, injectables) depend on correct use; barrier methods are less effective but uniquely also prevent sexually transmitted infection; and natural methods are the least effective.

WHY 'effectiveness' Depends on the User, Not Just the Method

A concept that transforms contraceptive counselling is why methods are judged by 'typical use' rather than 'perfect use' effectiveness. Every method has a theoretical failure rate achieved when it is used perfectly — but real people forget pills, run out of supplies, and use condoms inconsistently. The gap between the two can be enormous: the combined oral contraceptive pill is over 99% effective in perfect use, but only about 91% effective in typical use, because a pill must be remembered every single day for decades. Methods that depend on the user therefore fail far more often in practice than their impressive theoretical figures suggest. This is precisely the argument for the long-acting reversible contraceptives (LARC) — the copper IUCD, the LNG-IUS and implants — whose effectiveness is essentially the same in typical as in perfect use, because once inserted there is no daily decision to be made, nothing to remember and nothing to run out of; their typical-use failure rates rival sterilisation, yet they are fully reversible. Understanding that the commonest cause of contraceptive failure is not the method but its use explains why LARC is now promoted so strongly, and why counselling must match the method to the woman's life, not merely to her preference.

WHY the Condom Remains Indispensable

A point of great public-health importance is why the condom retains a unique place despite being far from the most effective contraceptive. Its typical-use failure rate (around 18%) is poor compared with an IUCD or an implant. Yet it is the only contraceptive method that also provides a barrier against sexually transmitted infection — including HIV, gonorrhoea, chlamydia and, importantly, HPV. No hormonal method, no IUCD and no sterilisation offers any protection whatever against infection: a woman with an implant is fully protected from pregnancy and entirely unprotected from HIV. This is why the concept of 'dual protection' is emphasised — using a highly effective method for contraception together with a condom for infection, particularly for young people, those with multiple partners, and anyone at risk. The condom is also cheap, needs no prescription, has no systemic side-effects and is under the man's control (making it one of the few methods that shares contraceptive responsibility). Understanding that pregnancy and infection are two separate risks requiring two separate defences explains why the condom cannot be replaced by more effective contraception, and why it remains central to reproductive health.

• Methods: barrier (condom, diaphragm), hormonal (COC, pop, DMPA, implant), intrauterine (Cu-IUCD, LNG-IUS), permanent (tubectomy, vasectomy) and natural.
• Judge methods by typical-use, not perfect-use, effectiveness — LARC (IUCD, LNG-IUS, implant) is best because it removes user error.
• The condom is the only method that also prevents STI/HIV — hence 'dual protection'.
• COC: inhibits ovulation; reduces ovarian and endometrial cancer; avoid in smokers over 35, hypertension and thromboembolic risk.
• Cu-IUCD (CuT 380A) lasts 10 years and also serves as emergency contraception up to 5 days; LNG-IUS also treats menorrhagia.