Delayed periods are common, with pregnancy being the most common cause. But there are other medical and lifestyle factors that can affect the menstrual cycle and cause a delay. Weight changes, hormonal disorders and menopause are among the most common causes of late periods. These problems can lead to missing a period for one or two months, or even amenorrhea – the absence of a period for three or more months in a row. Normally, menstrual bleeding occurs around the 28th day, but it can vary and be up to the 35th day. If the delay is longer than this period, the reason must be established. Intense stress can disrupt the production of gonadotropin-releasing hormone (GnRH), which regulates ovulation and the menstrual cycle. Both physical and psychological stress can lead to delayed periods. Missing a period due to a stressful situation is not unusual, but if you are going through prolonged stress and miss three or more periods, consulting a doctor is recommended. Polycystic ovary syndrome (PCOS) is a condition in which hormonal imbalances can lead to late or irregular cycles. Women with PCOS usually have other symptoms besides irregular periods. These symptoms may include weight gain or trouble losing weight, infertility, acne, hair loss or thinning, and growth of facial or body hair. Obesity affects the regulation of estrogen and progesterone and may be associated with missed periods. It can also cause fertility problems. In this case, weight loss can help regulate the menstrual cycle in overweight women. Being underweight can also harm the regularity of menstrual cycles. When the body is deprived of sufficient fat and other nutrients, it can have difficulty producing the necessary hormones. Women who suffer from anorexia or who have an excessively low calorie intake, as well as those who burn more calories through exercise than they take in, may become amenorrhoeic. Then weight gain usually helps restore menstruation. Rapid changes in weight caused by illness, medication, or dietary changes can also cause problems with the secretion or release of hormones, which can lead to a lack of periods. Primary ovarian failure occurs when the ovaries stop functioning normally before the age of 40. This can lead to irregular periods and fertility problems that begin before the typical age of perimenopause. Chronic diseases can affect the menstrual cycle. Some of these conditions include pituitary tumors, adrenal gland disorders, ovarian cysts, liver dysfunction, diabetes, and more.Congenital conditions such as Turner syndrome can also cause problems with menstruation and fertility. Acute illnesses such as pneumonia, heart attack, kidney failure, or meningitis can lead to rapid weight loss, nutritional deficiencies, or hormonal dysfunction, which can also lead to missed periods.