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Principles of contraception 

Principles of contraception

Chapter:
Principles of contraception
Author(s):

John Guillebaud

DOI:
10.1093/med/9780199204854.003.0806

November 28, 2012: This chapter has been re-evaluated and remains up-to-date. No changes have been necessary.

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Essentials

Continued use of any method of contraception is related directly to its acceptability. Advisers should be competent to give information about the efficacy, risks, side effects, advantages, disadvantages, and noncontraceptive benefits of each method.

Ignorance, especially about conditions not yet evaluated by the World Health Organization or the United Kingdom Medical Eligibility Committee, should be admitted during consultations, in which the clinician and the user, or couple, should be on equal terms: a ‘consultation between two experts’.

Too often, the combined oral contraceptive (‘the Pill’) is regarded as being synonymous with contraception. Providers everywhere should promote long-acting reversible contraceptives—injectables, implants and intrauterine methods—which can be forgotten about once administered; an essential attribute of effective continuing contraception.

Introduction

It should be self-evident that:

  • Human needs, along with those of all other species sharing the world, will never be met sustainably without stabilizing human numbers: currently increasing, according to the Population Reference Bureau (www.prb.org) by more than 82 million a year and reaching 7000 million in 2011.

  • No woman on Earth who wishes to exercise the right to control her own fertility should be denied the means to do so, by her partner or an outside agency, or through lack of correct information or choice of affordable and accessible contraceptives.

To be effective, contraceptives must be used correctly, consistently, and continuously. Continued use of any contraceptive is related directly to its acceptability. Therefore, couples should be given accurate information about all methods that are medically appropriate and helped to choose what is best for them. Health professionals who give advice about contraception should be competent to give information about efficacy, risks, side effects, advantages, disadvantages, and noncontraceptive benefits of each method. Too often, the combined oral contraceptive (‘the Pill’) is regarded as being synonymous with contraception. Providers too rarely inform women about new, improved, reversible contraceptives, especially the long-acting reversible contraceptives, which are widely misunderstood. Box 8.6.1 presents a ‘wish list’ for an ideal contraceptive. No available method meets all these criteria, but the levonorgestrel intrauterine system (LNG-IUS) meets more than any other.

Most women who seek contraception are young and healthy. They present fewer problems than over-35s, teenagers, and those with intercurrent diseases or risk factors like high BMI and smoking.

Young people

For young people of both genders, ‘sex and relationships education’ (SRE) should be promoted rather than ‘sex education’. When seeking advice on sex, relationships, contraception, pregnancy, and parenthood, young people are entitled to accessible, confidential, nonjudgemental, and unbiased support and guidance that recognizes the diversity of the traditions of their cultures and faiths. We should listen to their views and respect their opinions and choices. Valid choices include postponing sexual intercourse as well as having safer sex without risk of conception.

However, girls who start having sexual intercourse when they are very young (early coitarche) may escape becoming pregnant for several cycles, partly because a large proportion of early postpubertal menstrual cycles are infertile. As a result, they often do not seek advice until they have already conceived. Easier access to emergency contraception is an obvious priority. A socially enforced norm must be promoted, as it is in the Netherlands, that relationships may include sex only when contraception is adequate. Wherever mutual monogamy is uncertain, this must include condoms for safer sex. In this age group, long-acting reversible contraceptives should be offered more frequently. Whereas default in using the combined oral contraceptive leads to conception, long-acting reversible contraceptives have the ‘default state’ of contraception. Intrauterine methods are only relatively contraindicated in this age group, but injectables and implants are usually preferred.

Sexually transmitted infections

Taking a quick and practical sexual history should be part of all contraceptive consultations, not just those involving intrauterine devices or young people.

Ask:

  • ‘When did you last have sex?’ and then immediately

  • ‘When did you last have sex with anybody different?’

Much can be learnt from the second of this pair of open questions, whether the response is ‘about 20 years ago …’ or ‘3 months ago’ (the latter making it unthreatening to go on and clarify whether this was a change of partner or a one-night stand—and whether there have been others in the past year).

Relative effectiveness of available contraceptive methods

(Fig. 8.6.1)

Fig. 8.6.1 The choice of methods available in the UK, 2009. (Reproduced with kind permission of Dr Anne MacGregor.)

Fig. 8.6.1
The choice of methods available in the UK, 2009. (Reproduced with kind permission of Dr Anne MacGregor.)

Failure rates are usually expressed as conceptions per 100 woman-years. In Box 8.6.2, ‘perfect use’ means that the method is used consistently and correctly. ‘Typical’ use depends on such characteristics as age, social class, acceptability of conception, etc., in the population studied. Note the huge difference in failures between ‘perfect’ and ‘typical’ use of the combined pill (0.3 vs 8). The data come from the United States of America but the ‘perfect use’ figures can be used anywhere, for comparing methods.

a Failure rates given here are for ‘perfect’ users (using the method consistently and correctly) vs typical users. They are expressed as percentages of women unintentionally conceiving within the first year of contraception, except for (1) emergency contraception, where the failure rate is the percentage conceiving in that cycle out of 100 who presented after a single coital exposure, and (2) sterilization, where the failure rate is the percentage experiencing a failure within 10 years after the procedure.

b Failures are exceptionally rare and therefore the rate is difficult to estimate (0 failures in the 2500 users prior to marketing).

Table mainly modified from Family Planning Association (2009), with no claims to being fully comprehensive.

Iatrogenic (doctor-caused) pregnancies frequently result from avoidable errors and omissions by service providers, especially not allowing sufficient discussion time for new users.

Eligibility criteria for contraceptives

In general, contraceptive users are medically fit and can use any available contraceptive method safely. However, certain contraceptives pose health risks for people with medical conditions. Since most trials of new contraceptive methods deliberately exclude subjects with chronic medical conditions, there is little direct evidence on which to base sound prescribing advice.

WHO system for Medical Eligibility Criteria (WHOMEC)

These internationally agreed guidelines, initially devised at a World Health Organization Workshop in Atlanta in 1994, are based on evidence-based systematic reviews and expert opinion. In 2006, the Faculty of Family Planning & Reproductive Health Care (FFPRHC) developed a version of WHOMEC adjusted for British practice (UKMEC), and this is strongly recommended.

The WHO classification is summarized in Box 8.6.3. Clinical judgement is required: (1) In all WHO 3 conditions; or (2) if more than one condition applies. As a working rule, two WHO 2 conditions move the situation to WHO 3; and if any WHO 3 condition applies, the addition of either a WHO 2 or a WHO 3 condition normally means WHO 4, i.e. ‘Do not use’.

Prescribers often have to help couples make a decision, despite a frustrating absence of good evidence, or even for conditions not yet evaluated by WHOMEC/UKMEC, a clear statement of expert opinion. Such ignorance should be admitted and strongly underpins the concept that the consultation should always be on equal terms with the user: ‘a consultation between two experts’.

Further reading

Campbell M (2006). Consumer behaviour and contraceptive decisions: resolving a decades-long puzzle. J Fam Plann Reprod Health, 32, 241–4.Find this resource:

Guillebaud J (2001). Commentary—Medical-eligibility criteria for contraceptive use. Lancet, 357, 1378–9.Find this resource:

Guillebaud J (2007). Contraception today, 6th edition. Informa Healthcare, London.Find this resource:

    Guillebaud J (2009). Contraception—your questions answered, 5th edition. Churchill Livingstone, Edinburgh.Find this resource:

      Family Planning Association (2009). Your guide to contraception. Family Planning Association, London.Find this resource:

        Websites

        Cochrane Collaboration. Cochrane systematic reviews in fertility regulation. www.cochrane.org/reviews/en/topics/64.html

        Faculty of Family Planning and Reproductive Health Care (2006). UK Medical Eligibility Criteria. http://www.ffprhc.org.uk/admin/uploads/298_UKMEC_200506.pdf [See especially the Summary Table for all Common Reversible Methods 143–8.] Also UK Selected Practice Recommendations www.ffprhc.org.uk/admin/uploads/Final%20UK%20recommendations1.pdf

        National Institute for Health and Clinical Excellence (2005). The effective and appropriate use of long-acting reversible contraception. www.nice.org.uk/Guidance/CG30.

        Royal College of Obstetricians and Gynaecologists (2003). Male and female sterilization. Evidence-based Guidelines No 4. http://www.rcog.org.uk

        World Health Organization (2004). WHO Medical Eligibility Criteria (WHOMEC) for contraceptive use, 3rd edition. http://www.who.int/reproductive-health.

        World Health Organization (2005). WHO Selected Practice Recommendations (WHOSPR) for contraceptive use, 2nd edition. http://www.who.int/reproductive-health.