Physical stress such as illnesses can delay the menstrual period, according the Summit Medical Group. Rapid weight loss or weight gain can also interrupt menstrual cycles.
According the Summit Medical Group, a period isn’t considered delayed until a woman’s menstrual cycle has been delayed five or more days. After six or more weeks, the period is missed. In addition to illness, many conditions can cause a delayed menstrual cycle. For example, mental stress, pregnancy and hormonal imbalance may interrupt the cycle.
Women with late periods should see a physician if they experience abdominal pains or vaginal discharge. Women should also seek medical attention if their period stops for more than 90 days or if their periods become more than 35 days apart, suggests Mayo Clinic.