What are the recommendations for using a low-dose combined oral contraceptive pill (OCP)?

Recommendations for Low-Dose Combined Oral Contraceptive Pills (COCPs)

Low-dose combined oral contraceptive pills are an effective contraceptive method with a 4-7% failure rate with typical use, but require consistent daily use to maintain effectiveness and prevent pregnancy. 1

Effectiveness and Mechanism of Action

• Seven days of continuous combined hormonal contraceptive use is necessary to reliably prevent ovulation, with the recommendations balancing simplicity and scientific precision 2
• Combined oral contraceptive pills (COCPs) are the most commonly used reversible method of contraception in the US, comprising 21.9% of all contraception in current use 1
• COCPs work primarily by inhibiting ovulation, though they also thicken cervical mucus and alter the endometrial lining 2
• Studies show that when pills are taken correctly, the risk of ovulation is low, and even when ovulation occurs, cycles are usually abnormal 2

Recommendations for Missed Pills

If one hormonal pill is late (<24 hours since scheduled time):

• Take the late pill as soon as possible
• Continue taking remaining pills at the usual time (even if taking two pills on the same day)
• No additional contraceptive protection needed
• Emergency contraception generally not needed 2

If one hormonal pill has been missed (24 to <48 hours since scheduled time):

• Take the most recent missed pill as soon as possible (discard other missed pills)
• Continue taking remaining pills at usual time
• Use backup contraception (e.g., condoms) until pills have been taken for 7 consecutive days
• If pills were missed in the last week of hormonal pills, omit the hormone-free interval 2

If two or more consecutive hormonal pills have been missed (≥48 hours):

• Take the most recent missed pill immediately
• Continue taking remaining pills at usual time
• Use backup contraception until pills have been taken for 7 consecutive days
• Consider emergency contraception if pills were missed during the first week and unprotected intercourse occurred in the previous 5 days 2

Blood Pressure Monitoring

• Blood pressure should be checked prior to initiation of combined hormonal contraceptives 2
• Once started, blood pressure should be monitored at follow-up visits, with recommended frequency ranging from every 6 months to annually 2
• If blood pressure increases significantly without another identifiable cause, the COCP should be discontinued 2
• Studies examining increases in blood pressure after COCP initiation found mixed results, with few women developing hypertension 2

Risk Assessment and Contraindications

• COCPs are contraindicated in women with current or past breast cancer 3
• For women with hypertension, the Medical Eligibility Criteria (MEC) designates:
  • Class 3 risk (risks usually outweigh benefits) for women with adequately controlled hypertension or with SBP 140-159 mmHg or DBP 90-99 mmHg
  • Class 4 risk (unacceptable health risk) for those with SBP ≥160 mmHg or DBP ≥100 mmHg 2
• Smoking in combination with COCP use substantially increases the risk of myocardial infarction, especially in women over 35 years old 3
• Estrogen-containing methods increase the risk of venous thrombosis from 2-10 events per 10,000 women-years to 7-10 events per 10,000 women-years 1

Practical Recommendations for Use

• Women who frequently miss COCPs should consider an alternative contraceptive method that is less dependent on user adherence (e.g., IUD, implant, or injectable) 2
• New users of oral contraceptives should be started on preparations containing 0.035 mg or less of estrogen 3
• Studies comparing 7-day hormone-free intervals with shorter intervals found lower pregnancy rates and greater suppression of ovulation with shorter intervals 2
• Studies comparing 30-μg ethinyl estradiol pills with 20-μg ethinyl estradiol pills showed more follicular activity when lower-dose pills were missed 2

Vomiting and Diarrhea Considerations

If vomiting or diarrhea occurs within 24 hours after taking a hormonal pill:

• No need to take another pill
• Continue taking pills daily at usual time
• No additional contraceptive protection needed 2

If vomiting or diarrhea continues for 24 to <48 hours or ≥48 hours:

• Continue taking pills daily at usual time
• Use backup contraception until pills have been taken for 7 consecutive days after vomiting/diarrhea resolves
• Consider emergency contraception if appropriate 2

Common Pitfalls and Caveats

• Inconsistent or incorrect use is a major cause of COCP failure 2
• Extending the hormone-free interval is particularly risky for contraceptive failure 2
• Lower-dose pills (20-μg ethinyl estradiol) may have less room for error when pills are missed compared to higher-dose formulations 2
• The risk of cardiovascular disease with COCP use may increase with age, particularly after age 40, even with newer low-dose formulations 3
• For women over 40, the benefits of low-dose COCP use by healthy non-smoking women may outweigh the possible risks when compared to potential health risks associated with pregnancy 3