- - - - - Moderate to severe stress - Sexually transmitted infection -
Cigarette smoking
Recreational drug use
Moderate to excessive drinking (more than 6 drinks a week or more than 2 drinks at a time)
Polycystic ovarian syndrome (PCOS)
Endometriosis
Fibroids / polyps in the uterus
Early menopause (before age 40)
Cancer
Thyroid disorder
Diabetes or insulin resistance
Chronic depression
Disease of the liver or kidney