Myths vs facts: CYP1A2 and Fruchtbarkeit

The claim that CYP1A2 genotype directly determines fertility is largely a myth. CYP1A2 primarily metabolizes caffeine. Some observational studies suggest that women with the slow-metabolizer variant (e.g., rs762551, AA) who consume high caffeine may have a slightly increased time-to-pregnancy. However, effect sizes are small, findings are inconsistent, and no causal mechanism is established. Fertility is multifactorial: age, hormones, lifestyle, weight, stress, and medical conditions dominate. Evidence is human-observational/mixed, not strong. A genetic test alone cannot predict fertility. For those trying to conceive, moderate caffeine intake (≤200 mg/day per guidelines) is reasonable regardless of genotype. The clinical utility of CYP1A2 testing for fertility remains unproven.