What is the safest and most effective contraceptive method for a woman with Hashimoto thyroiditis?

Contraception in Hashimoto Thyroiditis

All standard contraceptive methods are safe and effective for women with Hashimoto thyroiditis, as this autoimmune thyroid condition does not create specific contraindications to any contraceptive option. 1

Key Clinical Principle

Hashimoto thyroiditis is an autoimmune disorder characterized by lymphocytic infiltration of the thyroid gland, leading to hypothyroidism in many cases, but it does not affect thrombotic risk, cardiovascular function, or hormonal metabolism in ways that would contraindicate specific contraceptive methods. 2, 3 The disease primarily affects thyroid function through antibody-mediated destruction of thyrocytes, but does not alter the safety profile of contraceptive hormones. 2

Recommended Contraceptive Options

First-Line: Long-Acting Reversible Contraceptives (LARCs)

The levonorgestrel-releasing intrauterine device (LNG-IUD) or subdermal implant should be considered first-line choices, as they are the most effective reversible options with failure rates less than 1% per year. 1

• LNG-IUD advantages: Provides highly effective contraception for 5-7 years, reduces menstrual bleeding by 40-50%, and induces amenorrhea in approximately 35% of users after 2 years. 4, 5, 6
• Implant advantages: Can be inserted at any time during the menstrual cycle if pregnancy is reasonably excluded, requires only backup contraception for 7 days if inserted more than 5 days after menses. 1
• Safety profile: Both methods are safe in women with obesity (BMI ≥30 kg/m²) without restriction. 1
• Long-term data: The LNG-IUD has been studied for up to 12-13 years of continuous use with excellent safety, showing mean hemoglobin increases of 1.35 g/dl due to reduced menstrual blood loss. 6

Copper IUD

• The copper IUD is a highly effective non-hormonal alternative with no systemic effects, making it particularly suitable for women who prefer to avoid hormones. 1, 5
• Contraceptive efficacy is similar to combined oral contraceptives when used correctly, with approximately 6 pregnancies per 1000 woman-years. 5
• Important caveat: May increase menstrual bleeding and cramping for several months after insertion, which could be problematic if the patient already experiences menstrual irregularities. 4, 5

Combined Hormonal Contraceptives (CHCs)

• CHCs (pills, patches, or rings) are safe for women with Hashimoto thyroiditis, as the condition does not increase thrombotic risk. 1
• Mandatory pre-initiation requirement: Blood pressure measurement must be performed before starting CHCs. 1
• Low-dose formulations containing 20 mcg ethinyl estradiol are appropriate for most women. 4
• Extended or continuous regimens can be used to manage dysmenorrhea if present. 7

Progestin-Only Methods

• Progestin-only pills (POPs): Require no examination before initiation and need backup contraception for 2 days (norethindrone/norgestrel) or 7 days (drospirenone) if started more than 5 days after menses. 1
• Depot medroxyprogesterone acetate (DMPA): Generally safe but should be used with caution in women at increased risk for osteoporosis, which may be relevant if the patient is on long-term glucocorticoid therapy for other conditions. 4

Clinical Implementation Algorithm

1. Assess patient preferences and medical history: Confirm diagnosis of Hashimoto thyroiditis and current thyroid function status. 2

2. Offer LARC as first-line: Present LNG-IUD or implant as most effective options with lowest failure rates. 1

3. If LARC declined or contraindicated:

   • Offer copper IUD for non-hormonal option 1
   • Offer CHCs if no cardiovascular contraindications (check blood pressure first) 1
   • Offer progestin-only methods as alternatives 1

4. Pre-insertion requirements:

   • For IUDs: Bimanual exam and cervical inspection required; screen for STIs if risk factors present but do not delay insertion unless purulent cervicitis visible. 1
   • For implant: No examination required. 1
   • For CHCs: Blood pressure measurement mandatory. 1

5. Special consideration for levothyroxine users: No drug interactions exist between levothyroxine and any contraceptive method, so standard dosing applies. 2

Important Clinical Pearls

• No thyroid-specific contraindications: Hashimoto thyroiditis does not create category 3 or 4 contraindications for any contraceptive method according to WHO Medical Eligibility Criteria. 1

• Pregnancy considerations: Women with Hashimoto thyroiditis and positive thyroid peroxidase antibodies have a 2-4 fold increased risk of recurrent miscarriages and preterm birth, making effective contraception particularly important until pregnancy is desired. 2

• Postpartum considerations: Women with Hashimoto thyroiditis may experience postpartum thyroiditis with transient hyperthyroidism followed by hypothyroidism, but this does not affect contraceptive choice. 8

• Barrier methods: Condoms and other barrier methods have no contraindications and can be used alone or as backup. 4

Common Pitfalls to Avoid

• Do not assume thyroid disease creates hormonal contraceptive contraindications: Unlike conditions affecting thrombotic risk or cardiovascular function, Hashimoto thyroiditis does not alter the safety of estrogen-containing contraceptives. 1

• Do not delay IUD insertion for STI screening: Unless purulent cervicitis is visible, IUD placement should proceed with concurrent STI testing if indicated. 1

• Do not require unnecessary examinations: BMI measurement is not required for medical eligibility, and pelvic exams are only needed for IUD insertion. 1