About one in ten Australian couples are infertile. Endocrine research has helped thousands of couples to have children. Endocrinologists diagnose and treat hormone imbalances that can cause infertility, and also assess and treat patients with reproductive problems. They work with patients who need hormone replacement. Problems treated by endocrinologists specializing in reproductive endocrinology include menopause symptoms, irregular periods, endometriosis, polycystic ovary syndrome (PCOS), premenstrual syndrome, and impotence.