Evidence check: CYP1A2 in the context of Fruchtbarkeit

The link between CYP1A2 and fertility is indirect, primarily through its role in estrogen metabolism and caffeine clearance. CYP1A2 hydroxylates estradiol; certain variants (e.g., rs762551) alter enzyme activity. 'Slow' metabolizers may have higher estrogen levels, potentially affecting fertility. Additionally, slower caffeine metabolism combined with high intake is associated with longer time-to-pregnancy and increased miscarriage risk. However, these findings come from observational studies with small effect sizes; no RCTs demonstrate clinical utility of CYP1A2 testing for fertility. Environmental, dietary, and lifestyle factors dominate. A single-gene test is insufficient for personalized fertility advice. Evidence is moderate, and results should not replace medical consultation. Safety note: high caffeine intake during pregnancy is discouraged regardless of genotype.