Menstrual periods typically last four to seven days and occur roughly every 28 days. Examples of irregular periods include periods that occur fewer than 21 days or more than 35 days apart, missing three or more periods in row, and menstrual flow that’s much heavier or lighter than usual

Symptoms and Causes: 

• Periods that occur fewer than 21 days or more than 35 days apart.
• Missing three or more periods in a row.
• Menstrual flow (bleeding) that’s much heavier or lighter than usual.
• Periods that last longer than seven days
• Periods that are accompanied by severe pain, cramping, nausea, or vomiting.
• Bleeding or spotting that happens between periods, after menopause or after sexual intercourse.
• Endometriosis may cause abnormal bleeding, cramps or severe pain before and during your period.
• Symptoms of PID include a heavy vaginal discharge with an unpleasant odor, irregular periods and pelvic pain.
• Thyroid or pituitary gland disorders affect your hormones. This causes your period to be irregular.

Polycystic ovary syndrome causes irregular periods.

Disruptions or changes in your daily routine can have an impact on your menstrual cycle. Some examples of lifestyle factors include:

• Stress.
• Gaining or losing a significant amount of weight.
• Exercise routines that result in very low body fat (long-distance runners, dancers or gymnasts).