6 reasons why your period is late

August 27, 2018

There can be several explanations for why your period may be late. From pregnancy to menopause as well as interference with glands that regulate hormone levels and problems with your reproductive organs.

Let’s start with a little physiology.

The brain produces a hormone known as Follicle Stimulating Hormone. It helps the ovaries produce follicles and facilitates ovulation. As the follicles become large they secrete oestrogen which in turn thickens the lining of the uterus (womb) in preparation for pregnancy.

In the absence of pregnancy, the ovaries stop producing hormones. Hence the lining of the womb has no more hormonal support – a bit like grass not being watered and fertilised. As a result, the lining of the womb sheds with a mixture of blood; coming out of the uterus, via the cervix into the vagina – a period.


Women who have missed at least three periods in a row are diagnosed with a condition called amenorrhea. This is the medical term for the absence of menstruation. It is recommended women seek advice from their GP or gynaecologist if they experience this issue.  When amenorrhea is properly identified and treated a period will usually return.

If other women in your family have experienced amenorrhea, you may have inherited a predisposition for the problem.

The 6…

  1. Pregnancy – Time to get a test and confirm!
  2. Stress – Emotional stress can temporarily dull an area of your brain called the hypothalamus which controls the hormones that regulate your menstrual cycle. Events of severe mental stress like the death of a family member, losing your job, or other significant emotional trauma this may cause your period (and ovulation) to stop. This is not a cause for alarm as regular periods usually resume when your stress decreases and returns to a more manageable level. Also, physical stresses from illness or injury such as severe burns or a heart attack can also cause a woman’s period to stop temporarily.
    Ways to keep your hormones regulated and your hypothalamus healthy include getting enough sleep, eating a balanced diet and regular exercise.
  3. Menopause – Women will also experience amenorrhea for natural reasons, such as pregnancy, breastfeeding and menopause. Menopause usually begins around age 50, however, some women may experience premature menopause where the ovarian supply of eggs diminishes before age 40, and menstruation stops. Women who reach menopause prior to 40 are referred to as having primary ovarian insufficiency. It may due to complete or partial loss of an X chromosome (Turner syndrome), the fragile X premutation, autoimmune ovarian destruction or for reasons which can’t always be explained. This may have implications for family members and a woman’s children, hence why it is important to see a gynaecologist to establish the cause.
  4. Sudden weight gain/weight loss – Sometimes lifestyle factors can contribute to the loss of your periods, such as excessively low body weight or excessive exercise. Women who struggle with eating disorders such as bulimia, anorexia or orthorexia and those under normal weight by 10% trigger abnormal hormonal changes which result in the loss of their period and ovulation. Professional athletes and those who train regularly in activities that tend to be associated with smaller frames like running, ballet and gymnastics may find their menstrual cycles interrupted due to the combination of stress, low body weight/fat and high energy expenditure. The reason why periods stop with excessive weight loss and exercise is because these stressors mimic a famine.  In part, periods signify that a woman is fertile and hence able to become pregnant. In a situation where there is famine woman will have excessive weight loss. The human body intuitively knows that this is not the best time to become pregnant and have children because they will likely starve.
  5. PCOS – A number of medical problems can cause hormonal imbalance, including, polycystic ovarian syndrome (PCOS). PCOS is the most common reproductive disorder in women but it is severely underdiagnosed.  Women with PCOS usually present with irregular periods however they also experience amenorrhea. PCOS causes high and sustained levels of hormones, rather than the fluctuating levels seen in the normal menstrual cycle. Physical signs of PCOS include excess hair, polycystic ovaries, ovulatory dysfunction, and metabolic issues, including obesity.
  6. Imbalance in Pituitary Hormones
    The brain contains a small gland called the pituitary gland. This is the control centre for many of the body’s hormonal functions. It secretes hormones like follicular stimulating hormone (FSH) that help the ovary to ovulate. When this hormone is absent or low, periods can be delayed or not occur at all. This situation may occur due to a mass (tumour) in the brain preventing secretion of FSH. Or due to an increase in Prolactin which suppresses the FSH from being secreted. Prolactin is the major hormone that helps produce breast milk. After birth and while breastfeeding, the prolactin plays an important role in order to space out pregnancies. This ensures humans can care for one child at a time. If prolactin levels become overactive and not after pregnancy, a woman may have irregular periods and start producing breast milk when in fact she has no child to breastfeed.

If a woman’s periods are becoming irregular or absent, it is important to see a gynaecologist to establish the cause and help reverse it. In some cases, this may be a simple as dietary and lifestyle changes, through to medication or surgery.

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