How are HDL and fertility related?

The provided context does not contain information on the relationship between HDL and fertility. In general scientific literature, HDL cholesterol is involved in steroid hormone synthesis, but there is no strong evidence for a direct causal role in fertility. Observational studies suggest associations between low HDL and reduced fertility in women (e.g., PCOS, endometriosis) and men (sperm quality), but these are not robust enough for clinical prediction or intervention. HDL is not an established fertility marker; AMH, FSH, and antral follicle count are more relevant. The evidence level is human-moderate (observational).