PCOS may cause symptoms: 1. Menstrual irregularities, missed periods, or very light periods 2. Large ovaries or ovaries with many cysts 3. Excessive body hair, such as on the chest, abdomen, and back (hirsutism) 4. Weight gain, especially around the abdomen (belly fat) 5. Oily skin or acne 6. Thinning hair or male-pattern baldness 7. Infertility 8. Overgrowth of skin on the neck or under the arms (skin tags) 9. A dark or thick patch of skin on the back of the neck, under the arms, and under the breasts.