Late period? Common causes of Amenorrhea

Has it been months since your last period? In medicine, if your period is late and has been missing for 3 months or more, it is called amenorrhea. There are several reasons for a missing cycle, and if you fit this description, it may be time to figure out what’s going on beneath the surface.

The American College of Obstetricians and Gynecologists have identified a woman’s menstrual cycle as a vital sign – as important as blood pressure or heart rate. The period is used to assess overall health status and when there are abnormal patterns in a cycle it can help identify potential health concerns.

What causes amenorrhea?

There are many potential causes of amenorrhea. I want to discuss some of the most common reasons for a young woman to lose their cycle, but first, it is important to note if your period is late, you must consider the possibility of pregnancy. If you are sure you are not pregnant, these are some causes of amenorrhea:

Polycystic Ovarian Syndrome (PCOS)

  • One of the signs of PCOS is an irregular cycle, typically longer than 35 days. If you are also experiencing weight gain, acne, unwanted hair growth on the face, chest or back your amenorrhea may be due to PCOS.

Hypothalamic Amenorrhea

  • This condition is caused by psychological stress, excessive exercise, disordered eating, or a combination of these factors, resulting in the suppression of hormone release from the brain, low estrogen levels and thus, no period.
  • When the female body is under physical or psychological stress, the last thing it wants to do it reproduce, and so there is a loss of the cycle.
  • Hypothalamic amenorrhea is responsible for 20-35% of cases of amenorrhea, so it is not uncommon. But the health consequences can be profound since estrogen has an important role in the health of our cardiac, skeletal, psychological, and reproductive systems.
  • This condition may be easily corrected through important lifestyle changes like increasing body fat and reducing the frequency/intensity of exercise.


  • Prolactin is a hormone that is released by the brain when a woman is breastfeeding, to support breastmilk production and help to prevent a subsequent pregnancy. But, prolactin can be elevated from certain medications, hypothyroidism or a tumour, as well. If prolactin is high in a woman who is not breastfeeding, this can explain why she lost her cycle and needs to be considered.

Post-Birth Control Amenorrhea

  • If you have recently stopped using the pill, an IUD, the patch, Nuvaring, or any other form of hormonal birth control, this may be why you have no period.
  • When a woman is on hormonal birth control the communication between the brain and the ovaries is shut down. The body relies on the external hormones to dictate the cycle. When you discontinue birth control, it can take some time for a regular period to return, as the brain and ovaries need to learn how to talk to each other again on their own.
  • Amenorrhea is one of many symptoms of Post-Birth Control Syndrome. If you want to learn more about symptoms post-pill, read this blog post.

Primary Ovarian Insufficiency

  • This condition is also known as Premature Ovarian Failure and basically means early menopause. This is a possible cause of amenorrhea in patients under 40 years old with a missing cycle.

What testing should be considered?

It is time to visit your doctor or naturopath if it has been 3 months without a period. At this point, some simple investigations should be done to evaluate the underlying cause of your amenorrhea. An initial evaluation should include these tests:

  • Pregnancy test
  • Luteinizing Hormone (LH)
  • Follicle-Stimulating Hormone (FSH)
  • Prolactin
  • Thyroid Stimulating Hormone (TSH)
  • Estradiol

If there is suspicion of PCOS, some additional testing should be done:

  • DHEA-S
  • Free and total testosterone
  • Fasting glucose
  • Fasting Insulin

Treating your amenorrhea depends on the cause, and there is no one-size-fits-all when it comes to treatment. Once further investigations are completed, your practitioner will be more clarity on how to get your cycle back.

As stated earlier, having a regular period is essential for overall health. If you have had no cycle for over 3 months, I strongly recommend speaking with a healthcare professional. Most causes of amenorrhea are reversible and this can have a huge impact on your health!

In health and bringing back absent periods,
Dr. Bronwyn

Image by @mandy_pierce_

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Dr. Bronwyn is a naturopathic doctor in Toronto, Ontario with a clinical focus in Women's Health. She works with women transitioning off the oral contraceptive pill and those with specific fertility concerns, to reach a state of hormonal balance or in preparation for a healthy pregnancy. Dr. Bronwyn is passionate about empowering women to reclaim their hormonal health, to enable a full and vibrant life.