In fact, the decrease in menstrual volume and black color after taking short-acting pills for a long time is mainly due to the contraceptive mechanism of the pill, which can prevent pregnancy mainly because it can change the thickness of the endometrium. The endometrium will become thinner and thinner, and the menstrual flow will gradually decrease and become darker, and some people may experience amenorrhea by taking short-acting contraceptives. Once this happens, you can stop taking short-acting contraceptives. If you have resumed menstruation after stopping short-acting contraceptives, and the volume and color of your menstruation have returned to normal, you can consider taking short-acting contraceptives again after 3 months.