What are the pros and cons of using progestin-only contraceptives, such as Mirena (levonorgestrel-releasing intrauterine system (LNG-IUS)) and Micronor (progestin-only pill (POP)), for birth control?

Pros and Cons of Progestin-Only Contraceptives

Progestin-only contraceptives are strongly recommended for women with contraindications to estrogen, particularly those with thrombophilia, positive antiphospholipid antibodies, or high risk of venous thromboembolism, as they provide effective contraception without increasing thrombosis risk. 1, 2

Types of Progestin-Only Contraceptives

1. Progestin-Only Pills (POPs or "Mini-Pills")

• Mechanism: Primarily work by thickening cervical mucus, not consistently inhibiting ovulation 1
• Effectiveness:
  • Typical use failure rate higher than other progestin-only methods due to strict adherence requirements 1
  • Approximately 0.5% failure rate with perfect use 2
• Administration: Must be taken at the same time daily for maximum effectiveness

2. Levonorgestrel-Releasing Intrauterine System (LNG-IUS/Mirena)

• Effectiveness: >99% effective with failure rate <1% 2
• Duration: Provides contraception for 3-7 years depending on the specific product
• Placement: Requires healthcare provider for insertion and removal

3. Progestin Implants

• Effectiveness: >99% effective
• Duration: Provides contraception for 3-5 years
• Placement: Requires healthcare provider for insertion and removal

4. Injectable Progestins (DMPA/Depo-Provera)

• Effectiveness: Highly effective when administered on schedule
• Administration: Injection every 12 weeks
• Note: Some concerns about thrombogenicity compared to other progestin-only methods 1

Advantages of Progestin-Only Contraceptives

1. Safety in High-Risk Populations:

   • Safe for women with contraindications to estrogen 1, 2
   • No increased risk of venous thromboembolism (VTE) with progestin-only pills or LNG-IUS 1
   • Strongly recommended for women with positive antiphospholipid antibodies 1
   • Safe for women with SLE with stable or low disease activity 1

2. Minimal Cardiovascular Risk:

   • No increased risk of stroke with progestin-only pills (RR 1.02,95% CI 0.72-1.44) 2
   • VTE risk with progestin-only pill is not increased (RR 0.90,95% CI 0.57-1.45) 1
   • VTE risk with progestin IUD is not increased (RR 0.61,95% CI 0.24-1.53) 1

3. Additional Non-Contraceptive Benefits:

   • LNG-IUS can reduce menstrual bleeding and may be used for treatment of heavy menstrual bleeding 2
   • Can be used for menstrual suppression in patients with bleeding disorders or those undergoing chemotherapy 1
   • May be suitable for patients on teratogenic medications 1

4. Suitable During Breastfeeding:

   • Can be used safely during breastfeeding 3
   • Does not affect milk production 2

5. Immediate Postpartum Use:

   • Can be started immediately postpartum, unlike combined hormonal contraceptives 3

Disadvantages of Progestin-Only Contraceptives

1. Irregular Bleeding Patterns:

   • Most common side effect across all progestin-only methods 4, 3, 5
   • Unpredictable vaginal bleeding during first months of use 5
   • May lead to discontinuation if patients are not adequately counseled 4

2. Strict Adherence Requirements (for POPs):

   • Must be taken at the same time daily 1
   • Missed pills can significantly reduce effectiveness 1
   • Higher typical use failure rates compared to long-acting methods 1

3. Provider-Dependent Methods (for LNG-IUS and implants):

   • Require healthcare provider for insertion and removal
   • Initial cost may be higher than oral methods

4. Specific Concerns with DMPA:

   • Possible increased risk of HIV acquisition (evidence inconclusive) 1
   • Higher VTE risk than other progestin-only methods (RR 2.67,95% CI 1.29-5.53) 1
   • Not recommended for women with positive antiphospholipid antibodies due to thrombosis concerns 1

5. Other Potential Side Effects:

   • Weight changes
   • Mood changes
   • Headaches
   • Breast tenderness 4

Special Considerations

For Women with Rheumatic and Musculoskeletal Diseases

• Progestin-only contraceptives or IUDs strongly recommended for women with positive antiphospholipid antibodies 1
• No data suggesting increased SLE flare risk with progestin-only pills 1
• IUDs (levonorgestrel or copper) strongly recommended in women with positive aPL 1

For Women at High Risk for HIV

• Advantages of DMPA outweigh theoretical or proven risks 1
• Women should not be denied access to DMPA based on HIV risk 1
• HIV prevention measures should be strongly encouraged alongside contraceptive use 1

For Adolescents

• Progestin-only pills provide an option for those with safety concerns about estrogen 1
• Long-acting methods may be preferable due to higher typical effectiveness rates 2

Algorithm for Selecting a Progestin-Only Method

1. Assess for contraindications to estrogen:

   • History of VTE, stroke, or ischemic heart disease
   • Positive antiphospholipid antibodies
   • Thrombogenic mutations
   • Complicated valvular heart disease
   • Smoking in women ≥35 years
   • SLE with moderate to severe disease activity

2. If any contraindications to estrogen exist:

   • First choice: Consider long-acting reversible contraceptives (LNG-IUS or implant) for highest effectiveness
   • Second choice: Progestin-only pills if patient prefers oral method and can adhere to strict timing
   • Avoid DMPA in women with positive aPL due to potential thrombogenicity

3. If no contraindications to estrogen but patient prefers progestin-only method:

   • Counsel on irregular bleeding as main side effect
   • Discuss effectiveness rates and user requirements for each method
   • Select method based on patient preference and lifestyle factors

4. For all patients using progestin-only methods:

   • Provide thorough counseling about expected bleeding patterns
   • Educate about correct use and what to do if doses are missed (for POPs)
   • Schedule follow-up to assess satisfaction and address concerns

By understanding the pros and cons of progestin-only contraceptives, healthcare providers can help patients make informed decisions that align with their medical needs and personal preferences.