Hello, Thank you for your question. The average adult menstrual cycle lasts 28 to 35 days. Your cycle is 38th days it is mean your period is missed or delayed. Do you use any contraception method? In this case you need to rule out your pregnancy. By do urine test. You can buy from out of the counter pharmacy. After you rule out pregnancy if there is no pregnant. You should go to see your doctor to evaluate your missed period. There are many cause of missed period. It is can be transient, intermittent, or permanent condition resulting from dysfunction of the brain(hypothalamus, pituitary), ovaries, uterus, vaginal or thyroid hormone. Secondary amenorrhea is defined as the absence of mense for more than three months in girl or women who previously had regular menstrual cycle or six months in a girl or women who previously had regular menses. Pregnancy is a common cause of secondary amenorrhea and should be excluded based on a sensitive pregnancy test. other cause that is possible are hypothalamic dysfuntion/tumor, some risk factors such as eating disorder(anorexia), excessive exercise, and stress, nutritional deficiencies make sure about your BMI is good, role of leptin deficiency, sysmic illness, obesity and ects... The management is overall goals of managment in women with secondary amenorrhea include: if you are pregnancy you need to take to see your doctor for pregnancy care. other we cprrecting the underlying pathology if possible, Helping the woman to achieve fertility is desired, preventing complications of the disease process(eg, estrogen replacement to prevent osteoporosis). You should see your doctor to find out what you have. Propone tablet is recommend now. Hope I have answer your query. Let me know if I can assist you further. Best regards, Dr. Heang Chan Raksmey, General and family Physician.