What is the best oral contraceptive (OC) pill to start with in Canada?

Best Oral Contraceptive Pill to Start in Canada

For most women in Canada, a combined oral contraceptive pill containing levonorgestrel or norethisterone with ≤35 mcg of ethinyl estradiol is the best first-line oral contraceptive option due to its effectiveness, relatively low risk of venous thromboembolism, and availability through the healthcare system. 1

Types of Oral Contraceptives Available

There are two main categories of oral contraceptives to consider:

1. Combined Hormonal Contraceptives (CHCs)

• Contain both estrogen (usually ethinyl estradiol) and progestin
• First-year typical failure rate: 5% 2
• Perfect use failure rate: 0.1% 2
• Continuation rate at one year: 71% 2

2. Progestin-Only Pills (POPs)

• Contain only progestin, no estrogen
• First-year typical failure rate: 5% 2
• Perfect use failure rate: 0.5% 2
• Approximately 9 out of 100 women become pregnant in the first year with typical use 3

Selection Algorithm for Oral Contraceptives

Step 1: Screen for Contraindications to Combined Hormonal Contraceptives

Avoid CHCs in women with:

• History of venous thromboembolism (VTE) or arterial thrombotic disease 4
• Current or history of breast cancer 5
• Liver tumors or active liver disease 5
• Uncontrolled hypertension 4
• Migraine with aura 4
• Age ≥35 years who smoke 4
• Multiple cardiovascular risk factors 4

Step 2: Choose the Appropriate Pill Type

If no contraindications to CHCs:

• First choice: Combined pill with levonorgestrel or norethisterone + ≤35 mcg ethinyl estradiol 1
  • These provide effective contraception
  • Have relatively lower risk of VTE compared to newer progestins
  • Are available through the Canadian healthcare system

If contraindications to CHCs exist:

• Alternative: Progestin-only pill (POP)
  • Safe for women with contraindications to estrogen
  • Requires more precise timing of administration
  • May be associated with more irregular bleeding patterns 3

Step 3: Consider Special Situations

For women with PMDD:

• Consider drospirenone-containing CHCs, which are FDA-approved for PMDD 5
• Effectiveness for PMDD beyond three menstrual cycles has not been evaluated 5

For women with acne:

• Drospirenone-containing CHCs are indicated for moderate acne vulgaris in women ≥14 years 5

For women with problematic menstrual symptoms:

• Extended or continuous regimens may be beneficial 6
• These regimens can improve health-related quality of life in women who find their menses problematic 6

Important Counseling Points

Effectiveness

• Emphasize that effectiveness depends on correct and consistent use
• Typical failure rates (5%) are higher than perfect use rates (0.1-0.5%) 2

Side Effects

• Common side effects include unscheduled spotting or bleeding, especially during the first 3-6 months 3
• These bleeding irregularities are generally not harmful and usually improve with persistent use 3
• Enhanced counseling about expected bleeding patterns reduces method discontinuation 3

Special Considerations

• Vomiting or diarrhea can affect pill absorption
  • If vomiting occurs within 24 hours of taking a pill, no additional action needed
  • If vomiting/diarrhea continues for 24-48 hours, backup contraception should be used 3

Pitfalls to Avoid

1. Not considering drug interactions: Effectiveness may be reduced when used with anticonvulsants, certain antimicrobials, HIV protease inhibitors, or St. John's wort 4

2. Overlooking VTE risk: The risk of VTE with CHCs is 3-4 per 10,000 woman-years compared to 1 per 10,000 woman-years in non-users 5

3. Failing to consider extended regimens: Extended pill regimens with fewer or no inactive pills may be preferable for some women 1

4. Inadequate counseling on correct use: The most common reason for contraceptive failure is incorrect or inconsistent use

5. Not discussing emergency contraception: Emergency contraception should be discussed as a backup method in case of missed pills or other contraceptive failures 7