What role does CYP2D6 play in fertility?

CYP2D6 is a key drug-metabolizing enzyme involved in breaking down estrogens and certain medications used in fertility treatments (e.g., tamoxifen, some antidepressants). However, a direct, clinically meaningful role of CYP2D6 variants in natural fertility is not well established. Most evidence relates to hormone or drug metabolism rather than fertility outcomes like egg quality, sperm function, or implantation rates. The evidence is therefore best described as mechanistic or unclear. Direct-to-consumer DNA tests for CYP2D6 in the context of fertility are not clinically validated for this purpose and should not guide decisions without specialist input. Consulting a reproductive endocrinologist is recommended before interpreting such results.