What to watch with TSH and fertility?

When monitoring TSH for fertility, the key is thyroid function. A TSH above 2.5 mU/L is often considered suboptimal for conception and linked to higher miscarriage risk. Genetic variants in TSHR (e.g., rs1991517) can slightly alter TSH sensitivity, but their effect is small and not actionable without lab values. A blood test measuring TSH, free T3, free T4, and thyroid antibodies is essential. DNA tests alone cannot diagnose thyroid dysfunction. If TSH is elevated, medical evaluation and possibly levothyroxine therapy are recommended. Evidence: human-moderate (guidelines, cohort studies).