A menstrual cycle is counted from the last day of the period to the start of the next period. The period is considered irregular if it takes 38 days or longer than the defined duration.

Irregular periods can be due to many reasons which can be from hormonal imbalances to many other underlying conditions. The conditions are evaluated by the doctor. Here are some possible causes and symptoms.

Pregnancy – Pregnancy can be the cause for you to experience spotting or miss the period. You may feel fatigued, breast tenderness or tingling sensation, sensitive to smells, morning sickness, and nausea. If you had sex recently and missed the period, take a pregnancy test at home or see your doctor and find out if you are pregnant.

Hormonal birth control – Irregular bleeding can be caused by hormone-containing intrauterine devices (IUDs) or hormonal birth control pills. Pills cause spotting between periods and may result in lighter periods.

Breastfeeding – If you are breastfeeding then you may have light periods or no periods at all. Breast milk is produced due to the Prolactin hormone. Prolactin is responsible for suppressing the periods while you breastfeed. Your periods will return after you stop breastfeeding.

Perimenopause – It begins in the 40s or earlier. The symptoms may last four to eight years. It starts with the changes in your menstrual cycle. Changing levels of estrogen can cause the menstrual cycle to get shorter or longer.

Polycystic ovary syndrome (PCOS) – Irregular periods are common with PCOS. It may cause weight gain, male pattern of baldness, excess hair on body and face, and infertility.

Thyroid problems like underactive thyroid which causes heavy periods. A study shows 44% of those suffering from menstrual problems have thyroid disorders.

Uterine fibroids or muscular tumors form on the wall of the uterus. Most of these are noncancerous and their size varies from being as small as an apple seed to the size of a grapefruit. They make periods very painful and cause anemia. You will experience pain in the legs, pain during sex, low back pain, pelvic pain, and pressure. These can be managed with pain medications and iron supplements.

Endometriosis – It affects 1 in 10 women from reproductive age. The tissue that normally lines the uterus grows outside the uterus. It is painful and causes heavy bleeding, debilitating menstrual cramps, prolonged periods, and bleeding between periods.

Being overweight – This also causes menstrual irregularity. Research shows weight impacts the insulin and hormone levels that interfere with the menstrual cycle. Rapid weight gain, irregular periods is cause for PCOS, hypothyroidism, etc.

Extreme weight loss and eating disorders – Rapid weight loss, not eating enough calories, interferes with the production of hormones which are needed for ovulation. If you are underweight and have a lower body mass index than 18.5. You will experience headaches, fatigue, hair loss, etc.

Excessive exercise – Excessive and intense exercises interfere with the hormones that are responsible for menstruation. Female athletes usually develop amenorrhea –missed or stopped periods. Reducing the excessive exercises and training, and also increasing the food calories helps restore the periods over time.

Stress – This interferes with your menstrual cycle. It temporarily interferes with the part of the brain which controls the hormones that regulate your cycle. Your periods should return to normal after your stress decreases.

Medications – There are many medications which interfere with the menstrual cycle, like aspirin, ibuprofen, chemotherapy drugs, antidepressants, epilepsy drugs, thyroid medications, blood thinners, and hormone replacement therapy.

Cancer – Cervical and endometrial cancer causes changes in the menstrual cycles with heavy periods; bleeding between periods; bleeding during, after intercourse; unusual discharge, etc.