Contraception Planning for Women with Hypothyroidism on Levothyroxine
All standard contraceptive methods are safe and appropriate for women with hypothyroidism on levothyroxine, and you should offer the full range of options without restriction. There is no contraindication to any form of hormonal or non-hormonal contraception in this population 1.
Contraceptive Options
Recommended Approach to Counseling
Use a tiered counseling approach, presenting the most effective methods first 1:
Tier 1 (Most Effective): Long-acting reversible contraceptives (LARCs)
- Intrauterine devices (IUDs) - both hormonal and copper
- Contraceptive implants
Tier 2 (Moderately Effective): Short-acting hormonal methods
- Combined oral contraceptives (estrogen-progestin)
- Progestin-only pills
- Injectable contraceptives
- Contraceptive patch or ring
Tier 3 (User-Dependent): Barrier methods
- Condoms (should be made readily available) 1
- Diaphragms
Important Consideration: Hormonal Contraception May Be Protective
Recent evidence suggests hormonal contraception may actually reduce the risk of developing hypothyroidism 2. In a study of over 18,000 women, all forms of hormonal contraception showed protective effects, with progestin-only methods and IUDs having the strongest protective effect (odds ratios of 0.14 and 0.12 respectively), and combined estrogen-progestin contraceptives also showing significant protection (odds ratio 0.30).
TSH Monitoring When Using Hormonal Contraception
Key Monitoring Principle
Check TSH 4-8 weeks after initiating hormonal contraception, as estrogen-containing contraceptives can increase levothyroxine requirements 3.
Monitoring Algorithm
Baseline: Ensure TSH is at goal before starting contraception
- For non-pregnant women with hypothyroidism, maintain TSH within normal reference range 4
After Starting Hormonal Contraception:
- Measure TSH at 4-8 weeks after initiation 3
- This is particularly important for estrogen-containing methods (combined oral contraceptives, patch, ring)
- Progestin-only methods are less likely to affect levothyroxine requirements
Ongoing Monitoring:
- Once stable on contraception, return to routine monitoring every 6-12 months 3
- Recheck TSH 4-8 weeks after any change in contraceptive method or levothyroxine dose
Why This Matters
Estrogen increases thyroxine-binding globulin (TBG), which can reduce free thyroid hormone availability and potentially increase levothyroxine requirements. The FDA label explicitly recommends remeasuring TSH within 4-8 weeks when initiating drugs that alter levothyroxine bioavailability or metabolism 3.
Practical Implementation
Prescribing Considerations
- Provide one year's supply of hormonal contraceptives to reduce barriers to use 1
- Physical assessment is typically limited to blood pressure measurement before starting hormonal contraceptives 1
- No pelvic examination is required before prescribing oral contraceptives
- If reasonably certain the patient is not pregnant, any contraceptive may be started immediately 1
Common Pitfall to Avoid
Do not withhold or discourage hormonal contraception in women with well-controlled hypothyroidism. The interaction is manageable through TSH monitoring and dose adjustment if needed. Failing to offer the full range of contraceptive options may lead to unintended pregnancy, which carries far greater risks for women with hypothyroidism 4.
Special Consideration: Planning for Pregnancy
If the patient is planning pregnancy in the near future, counsel that:
- Levothyroxine requirements typically increase by 25-50% during pregnancy 3
- TSH should be checked as soon as pregnancy is confirmed 4, 3
- Target TSH <2.5 mIU/L in first trimester 4, 3
- Women planning conception with subclinical hypothyroidism benefit from levothyroxine treatment to reduce miscarriage risk 4