There are a variety of reasons why periods are irregular including stress, natural hormonal changes, starting or stopping birth control, excess weight gain/weight loss etc. The majority of reasons for irregular periods which is also known as oligomenorrhea have something to do with hormone levels.

The primary hormones that regulate the menstrual cycle are estrogen, progesterone, and follicle-stimulating hormone. Irregular periods suddenly can occur if something disturbs or changes the way these hormones rise and decrease during each cycle.

Let us more closely examine the common causes of irregular menstrual cycles:

*1. The onset of periods and menopause:*

Menarche, or the time when someone first starts menstruating, and menopause, when someone stops menstruating, are both times where the body undergoes significant hormonal changes. During puberty, the effects of irregular periods on the body can be experienced since the body goes through a lot of changes during this time.

During perimenopause, the earliest stage of menopause, periods become erratic as well. Hormone levels start to drop around this time. Periods may become longer and further apart until a person no longer has them.

*2. Starting Birth Control Methods:*

Hormonal contraception works by preventing ovulation which while using it, a person does not have a genuine period. Instead, some women do not have a period at all, while others get withdrawal bleeding that resembles a period.

During the first few months of using the pill, patch, implant, or hormonal intrauterine device (IUD), a person may experience irregular bleeding.

*3. Stopping Birth Control Methods:*

Similarly, if a woman stops using hormonal birth control, her periods may become irregular. It takes some time for the body’s hormonal cycle to return to normal.
People who had irregular periods before using hormonal birth control may experience them again once they stop using it.

*4. Underlying Health Conditions:*

Irregular period symptoms can sometimes be due to underlying health conditions like:

- PCOS
- Eating disorders such as anorexia nervosa, bulimia nervosa, and binge eating disorders.
- Endometriosis
- Thyroid disease
- Other irregular periods problems include – primary ovarian insufficiency, hormone-secreting tumours, Cushing’s syndrome, type 1 diabetes, etc.



Sources:

1-https://www.healthline.com/health/why-do-women-have-periods