Emergency contraception: A simple, safe, and effective approach to preventing pregnancy after unprotected intercourse

Introduction

Though emergency contraception (EC) has been in use for more than 25 years, studies continue to indicate that health professionals do not routinely counsel about EC, and men and women remain largely unaware of its availability.[1-3]

Up to half of pregnancies in Canada are unintended. Twenty percent of these proceed to an abortion, and that number increases to 50% in adolescents aged 15 to 19 years. Unintended pregnancy occurs not only when no method of contraception is used but, just as often, when a conventional method has failed. Emergency contraception (also called “morning after” treatment or postcoital contraception) is a safe and effective way of preventing an accidental pregnancy after unprotected sex. Use of emergency contraceptive pills can reduce the risk of pregnancy by at least 75% and use of a copper-bearing intrauterine device (IUD) can reduce the risk of pregnancy to less than 1%.[4] In Canada 30% of women will have had an abortion at some time during their reproductive lives. The continued high rates of unintended pregnancies and abortions demonstrate that contraception continues to be underused in Canada. It is clear that EC will have an impact on reducing unintended pregnancy only if women and men know about the methods and are able to access them when needed.

What’s available

There are three emergency contraceptive methods licensed for use in Canada: two hormonal preparations and the postcoital insertion of a copper-bearing IUD. Currently, emergency contraception options are available with a prescription from walk-in clinics and physician offices. Planned Parenthood clinics, some student health services, and youth clinics have emergency contraceptive methods immediately available. Since December 2000, emergency contraceptive pills have also been available directly to women (without a prescription) from many pharmacies in BC.

Indication for use

Emergency contraception should be considered for any woman who has had unprotected intercourse within the previous 72 hours and does not wish to be pregnant.

Emergency contraceptive pills (ECPs) may be offered for unprotected sexual intercourse at any time during the menstrual cycle and more than once per cycle if required. To help ensure that ECPs are taken as soon as possible after unprotected sex, they may be provided to a woman in advance of need. This is especially appropriate for women relying on a barrier method or natural family planning.

A copper-bearing IUD may be offered 5 days after unprotected intercourse at any time during the menstrual cycle.

Sexually transmitted diseases

It is important to ensure that men and women understand that emergency contraception provides no protection against sexually transmitted diseases (STDs). Any time emergency contraception is provided, both at assessment and again at follow-up, the clinician should provide counseling concerning STDs. Information ought to incorporate prevention and modes of transmission, including safer sex practices, signs and symptoms of STDs, and the availability of confidential testing. The use of latex condoms for all sexually active men and women should be consistently encouraged.

Emergency contraceptive pills

Emergency contraceptive pills are the most commonly used emergency contraceptive method. The current treatment schedule is one dose within 72 hours of unprotected intercourse followed by a second dose 12 hours later.[5] The two options are:

• Combined estrogen/progestin emergency contraceptive pills providing 0.1 mg of ethinyl estradiol and 0.5 mg of levonorgestrel in each of two doses separated by 12 hours (Ovral).

• Progestin-only emergency contraceptive pills providing 0.75 mg levonorgestrel in each of two doses separated by 12 hours (Plan B).

The progestin-only regimen is significantly more effective than the combined regimen and has a considerably lower incidence of nausea and vomiting. It reduces the risk of pregnancy by 85% (compared to 75% with the combined regimen) and is associated with a 50% lower incidence of nausea and a 70% lower incidence of vomiting.[6] For these reasons, the progestin-only regimen is likely to become the standard ECP treatment.

Alternate emergency treatment regimens can be created from other available low-dose oral contraceptive products available in Canada. The following products contain the hormones that have been most widely studied, and should be taken in each of two doses separated by 12 hours:

Mechanism of action

Multiple mechanisms of action of ECPs have been suggested. Studies have shown that ECPs can inhibit or delay ovulation.[6-8] ECPs may also prevent implantation by altering the endometrium.[9,10] Other possible mechanisms include interference with corpus luteal functioning, thickening of the cervical mucous, and alterations in the tubal transport of sperm or egg.[11,12] ECPs are not abortifacients and cannot and do not interrupt an established pregnancy.

Timing

Treatment should be initiated within 72 hours after unprotected intercourse. A recent randomized controlled trial conducted by the World Health Organization demonstrated that effectiveness of hormonal emergency contraception declined significantly with increasing delay between unprotected intercourse and the initiation of treatment.[6,13] This finding indicates that ECPs should be taken as soon as possible after unprotected intercourse.

If the second dose is taken earlier than or up to 24 hours rather than precisely at 12 hours, there may not be any significant reduction in efficacy, and though this practice still needs confirmation, it does allow for some flexibility if taking the second dose 12 hours later is difficult (e.g., if it falls in the middle of the night). Timing of the second dose can be altered (to slightly less than or slightly more than 12 hours) to improve compliance.[14] The effectiveness of ECPs does not drop to zero after 72 hours and may be provided up to 5 days after unprotected intercourse, though patients should be informed that the effectiveness is unknown if the method is delayed beyond 72 hours.[15]

Safety

The only absolute contraindication to use of emergency contraceptive pills is confirmed pregnancy, because they will not work if a woman is already pregnant. There are no other medical contraindications on currently available evidence. Because the dose of hormones is relatively small and the pills are used for a short period of time, the contraindications associated with regular use of oral contraceptives do not apply to emergency contraceptive pills. Progestin-only ECPs (or insertion of a copper-bearing IUD) may be the method of choice for women with particular medical conditions or risk factors in which there is an absolute contraindication to estrogen use (e.g., focal migraine at time of request or history of increased thromboembolic risk), or for those women who suffered severe nausea after taking the estrogen-progestin ECPs previously.

There is no evidence of teratogenicity when ECPs are inadvertently taken during pregnancy.[16]

If a woman is taking drugs that are known to reduce the efficacy of oral contraceptives through the induction of liver enzymes (e.g., rifampicin), the usual practice is to double the dose of ECP. However, it is not known whether this is necessary and its safety has not yet been formally evaluated.[17]

Side effects

The most commonly reported side effects are nausea and vomiting. With the combined ECP, 50.5% of women experience nausea and 18.8% report vomiting.[6,18] An anti-emetic such as 50 mg dimenhydrinate (Gravol) given orally 30 minutes before each dose may reduce the risk of nausea (by 27%) and vomiting (by 64%).[19] When prescribing the medication, it may be sensible to offer women an extra dose of ECP to be used if vomiting occurs within 1 hour of ingestion. For those women who have suffered severe nausea after taking the combined ECP regimen, the progestin-only ECP has been shown to have a significantly lower incidence of nausea and vomiting and should be the treatment of choice.[6] Other side effects include headache, bloating, and breast tenderness, but they are uncommon. There may be some menstrual disturbance, but most women have their menstrual period on time or slightly early.

Copper-bearing intrauterine device

A copper-bearing IUD has the highest efficacy of any currently available emergency contraception and is the method of choice where efficacy is the priority. The failure rate has been estimated to be less than 0.1%.[20]

Only copper-bearing IUDs are suitable for use as postcoital contraception.[21] Currently, the only available device in Canada, since the discontinuation of the Gynae-T380, is the Nova-T.

Mechanism of action

The primary action of the copper-bearing IUD is the induction of a foreign-body reaction within the endometrium and upper reproductive tract. This sterile inflammatory response is toxic to the sperm and egg and effectively interferes with transport or implantation. In addition, copper has a specifically toxic effect on sperm.

Timing

Regardless of the number of episodes of unprotected intercourse, a copper-bearing IUD can be safely and effectively inserted up to the time of implantation, which is 5 days after the most likely day of ovulation. (i.e., up to day 19 of a 28-day cycle). However, if it is difficult to determine the time of ovulation, it is recommended that use of the copper-bearing IUD be restricted to 5 days after unprotected intercourse.

The copper-bearing IUD can be removed during the patient’s next menstrual period or retained for up to 5 years.

Safety

It is important to establish that a woman is not already pregnant before inserting an IUD. Additional screening should follow the usual IUD screening criteria. Contraindications to regular copper IUD use include:

• Current pelvic inflammatory disease or STD

• Past history of severe pelvic inflammatory disease

• Known allergy to copper

• History of Wilson’s disease

• Undiagnosed vaginal bleeding

• Abnormalities of the uterus resulting in a distorted cavity

• Immunosuppressive disease (e.g., HIV, leukemia)

Because of the risk of postinsertion pelvic infection, women should be tested for STDs (including bacterial vaginosis) at the time of insertion. Appropriate antibiotic cover is advisable where an STD risk is suspected or identified.

Side effects

Common side effects for postcoital copper-bearing IUD insertion are the same as those for regular IUD use. At the time of insertion, possible side effects include uterine perforation, pain, and an increased risk of pelvic inflammatory disease (within the first 20 days after insertion). Later side effects include increased menstrual pain or bleeding.

Indications for using copper-bearing IUD rather than EC pills

In several situations, the copper-bearing IUD may be the preferred choice over emergency contraception pills:

• When the woman wants to use the IUD as her long-term method of birth control

• When the woman wants the most effective option available

• When there has been multiple exposures prior to 5 days after the calculated ovulation date

• Where presentation is more than 5 days after unprotected intercourse, but still less than 5 days after the calculated ovulation date

• Rarely, if severe nausea prevents a woman from taking ECPs even with an anti-emetic

Assessment

Almost all women can safely use emergency contraception. The only absolute contraindication is confirmed pregnancy. Questions about the date of the last normal menstrual period and timing of unprotected sex will, in most cases, rule out the possibility of an existing pregnancy. Occasionally when the menstrual cycle or sexual history is unclear, a pregnancy test may be necessary prior to treatment.

For all patients, the emergency contraception visit is a good opportunity for education and counseling about sexual health issues in general. Discussion should include recommendations about the regular use of a birth control method of choice and an assessment of the risk for STDs, with information provided on safer sex practices. Routine screening services such as breast examinations and guidelines for regular Pap testing should also be emphasized.

Emergency contraception follow-up

A follow-up visit with a health care provider should take place 3 to 6 weeks after emergency contraception. A pregnancy test is required if there has been little or no bleeding within 3 weeks of emergency treatment. The visit should include provision of ongoing contraception and STD testing and treatment as appropriate. A patient who plans to continue IUD use should receive routine follow-up care according to standard IUD protocols.

Forewarned and forearmed—Issues of access

Forewarned

Educating patients about the availability of emergency contraception in advance of need is an important opportunity for increasing its use. If women don’t know about emergency contraception, they will not request it.[22] Emergency contraception also has the potential to involve men in the contraception loop. Many men do not tell their partners when the condom breaks or slips for fear that there is nothing that can be done. Knowledge of emergency contraception and information about where and how to obtain it when it’s needed will relieve this anxiety and help improve communication between men and women around birth control.

Forearmed

The evidence that emergency contraception is most effective the sooner it is used after intercourse highlights the need for women to have immediate and ready access to it. Anything that delays a woman from starting emergency contraceptive pills impairs the effectiveness of the treatment. Providing women with advance prescriptions ensures that emergency contraceptive pills are taken as soon as possible after unprotected sex. Opportunities for providing advanced prescription of emergency contraceptive pills can occur during routine office visits or specifically at the time of birth control counseling visits.

It has been suggested that providing advance prescriptions of emergency contraceptive pills encourages irresponsible sexual behavior and undermines the use of traditional contraception. The evidence shows that the opposite is true. Advance prescription of emergency contraceptive pills does not lead to them being used more frequently, but does lead to fewer unintended pregnancies; there is also a strong temporal relationship between the use of emergency contraceptive pills and starting regular ongoing contraception within the following year.[23,24]

Conclusion

There is no reason why a woman should face an unintended pregnancy when there is a safe and effective alternative. Treatment with emergency contraception is a standard of care that Canadian health care providers are obliged to offer and may be negligent if they do not.[25] Since emergency contraception is most effective the sooner it is used after intercourse, it is incumbent on physicians and others involved in providing reproductive health care to ensure women who wish to obtain emergency contraception successfully receive it within the limited time frame.

Physicians have the potential to increase the use of emergency contraception and to significantly reduce the rate of unplanned pregnancy and abortion among British Columbians.

Competing interests

None declared.

Strategies to improve access to emergency contraception

• Information on the availability of EC should be displayed and distributed in offices and other health care facilities

• All staff who come into contact with patients (e.g., medical office assistants, receptionists, practice nurses, answering services) should be aware of the availability of EC

• EC should be part of every contraceptive counseling visit

• EC should be discussed routinely during regular office visits

• Provision of advance prescriptions of emergency contraceptive pills eliminates the need for unscheduled office visits and helps ensure that the treatment is started as soon as possible after unprotected sex

• Practices can develop their own packages containing emergency contraceptive pills for dispensing directly to their patients (standard dispensing practices, including labeling and instructions for use, must be followed)

Roey M. Malleson, MBBS, DFFP, MHSC

Dr Malleson is medical director of the Planned Parenthood Association of BC, medical director of the Youth Health Program, head of the Division of Adolescent Health at Children’s and Women’s Health Centre of British Columbia, and a clinical assistant professor in the Department of Family Practice, University of British Columbia.