Introduction

The invention of the oral contraceptive pill has proved one of the most important milestones in the history of medicine, at least as ranked by voters in a recent British Medical Journal poll. Introduced in the 1960s, combined oral contraceptive pills (containing both estrogen and a progestin) have become the most widely used method of reversible contraception in the world. The combined oral contraceptive pill (OC) is a highly effective method of reversible contraception. Failure rates are extremely low with perfect use (0.1%). But failure rates for typical use range from 2 to 9%. Contraceptive counselling needs to include an assessment of which method would best suit a woman’s medical needs as well as her lifestyle and ability to be adherent; in other words, the best “user-method fit.”

As the pill has evolved, it’s been modified in an effort to decrease side effects, maintain effectiveness, improve compliance, and extend the time on active pills beyond 21 days. The high levels of synthetic hormones used in early OCs were associated with greater health risks, so the estrogen and progestin dosages were decreased, leading to today’s low-dose formulations. Newer progestins, which theoretically may confer greater benefits and fewer side effects, have been developed. Most low-dose OCs contain 20-35 mcg of ethinyl estradiol (EE) in combination with a progestin.

In addition to providing effective contraception, the OC has many other health benefits including a decreased risk of endometrial and ovarian cancers, control of menstrual bleeding, improved cycle regularity, relief from cyclic pelvic pain, decreased acne and hirsutism, and decreased PMS symptoms.¹ Although the OC has been intensively studied and used by millions of women worldwide, there are still a number of controversies and myths and, therefore, many questions may arise when prescribing OCs.

Who should (or should not) take oral contraceptive pills?

In the absence of contraindications, the OC may be considered for any woman seeking a reliable, reversible method of contraception or who would like to take advantage of its non-contraceptive benefits.² In women with certain medical conditions or risk factors, OC use may be associated with an increased risk of complications. We’ll discuss contraindications and risks next month in part 2.

Age itself is not a contraindication to the OC. Experts agree that healthy, non-smoking women may continue to continue to take the OC until menopause² and that there is no “lower age limit” for starting the OC once menarche has occurred. Indeed, the WHO states that age alone is not a medical reason for denying any contraceptive method to adolescents.³ There is no evidence that starting the OC at a younger age is associated with a decrease in final adult height, an increased risk of cancer, or future fertility problems. Minors who present for contraception are usually considered to be mature and in most cases are entitled to confidentiality.⁴

What do you need to consider when starting the OC?

Before prescribing the OC, a history should rule out potential contraindications. The physical exam ought to include a BP check, but a pelvic exam — although an important part of well-woman care — is not mandatory prior to providing the OC.² Lab tests aren’t usually required.

The choice of pill for first time users should rest on clinician judgement and patient preference. Ideally, a low-dose pill (< 35 mcg EE) that provides effective contraception, acceptable cycle control, possible non-contraceptive benefits, and the least side effects for that particular woman is preferred. Unless the adverse events are severe or intolerable, she should try the pill for at least three months before considering switching to another — many of the initial “nuisance” side effects such as breakthrough bleeding, headache, nausea and bloating will resolve after the first three months of use.

Pills containing 20 mcg of EE have been shown to be as effective in preventing pregnancy as 30-35 mcg pills. These 20 mcg pills have comparable cycle control after the first few months of use and reduced symptoms of bloating and breast tenderness at the outset. A Cochrane Review, however, did find that 20 mcg pills had higher rates of bleeding pattern disruptions and early trial discontinuation.⁵ There’s no evidence that 20 mcg pills have better safety profiles than 30-35 mcg pills. Nor have multiphasic pills been shown to be safer or more effective than monophasic pills with the same dose of EE.

Much depends on the patient’s preference for frequency of menstruation. Current approved OC regimen choices include 21/7 (21 days of hormones with a 7 day hormone-free interval), 24/4 (24 days of active pills with a 4 day HFI), and 84/7 (84 days of active pills with a 7 day HFI). A 365-day regimen is available in other countries (an active pill is taken every day). Of course, this can also be achieved by using any of the monophasic pills that are currently available in Canada. Alternatively, a woman and her healthcare provider can design different regimen durations, provided that the HFI doesn’t exceed 7 days at any time.

What are the current recommendations for missed pills?

Counselling women on what to do if they miss a pill can be confusing. The revised WHO recommendations for missed OCs take into account the fact that the chance of pregnancy depends on when the pills are missed and how many are missed.³ The greatest chance of pregnancy occurs when the hormone-free interval (HFI) is extended by more than 7 days (i.e. at the beginning or end of the 21 days of active pills). The WHO suggests more caution with 20 mcg pills than with 30-35 mcg pills, although they recognize that there’s limited evidence to support this recommendation. According to the WHO, a woman taking a 30-35 mcg OC could miss up to 2 active hormonal pills or start a pack up to 2 days late without requiring backup or emergency contraception. Women taking a < 20 mcg OC could miss 1 active pill or start their pack one day late without requiring additional precautions. Those who missed 3 or more active 30-35 mcg pills (or 2 or more active 20 mcg pills) were advised to take an active pill as soon as possible, continue taking one pill daily, use a back-up method of contraception for 7 days, and consider the use of emergency contraception. If pills were missed in the third week, she should finish the active pills, omit the HFI, and then start a new pack of pills right away.

There was some controversy over the new WHO guidelines, and the Society of Obstetricians and Gynecologists of Canada (SOGC) published their own guidelines in 2008 for missed hormonal contraception. Notably, given the limited evidence available they did not distinguish between 20 mcg and 30-35 mcg pills.⁶ The guidelines are summarized in Table 2 (http://www.parkhurstexchange.com/node/5311)

Do OC’s have a role in acne therapy?

A reduction in acne and hirsutism is usually seen with OC use. This is mediated by an increase in sex hormone-binding globulin (SHBG), thereby reducing circulating free testosterone; by LH inhibition and decreased androgen synthesis, and decreased 5-alpha reductase activity in the skin. While only certain OCs have an official Health Canada indication for acne, almost all OCs will help to improve acne symptoms. The OC containing the anti-androgen cyproterone acetate is approved in Canada only for the treatment of moderate to severe acne but it’s also an effective method of birth control.

Women who have acne and require contraception may benefit from an OC provided that they have no contraindications. Those with moderate to severe acne may wish to consider this as a primary treatment option for acne, along with other therapy. Because it provides reliable contraception, it can be an excellent adjunct to teratogenic acne medications such as oral isotretinoin.

What’s the future of the oral contraceptive pill?

The OC continues to be the most commonly used method of reversible contraception in the world. We’ve seen the pill evolve as hormonal dosages have decreased, new synthetic progestins have been developed, and new dosing regimens have been approved. This process is bound to continue as researchers seek an effective OC with the fewest possible side effects and hopefully a number of non-contraceptive benefits.