This article has been medically reviewed by Dr Noortje Paridaans, gynecologist from the Netherlands, specializing in the diagnosis and surgical treatment of Endometriosis. Aside from her specialisation, she focuses on enforcing women in their health journey, by creating awareness for women's health, making podcasts and reviewing medical information.
We have all been there. That anxiety-provoking moment when you weren’t expecting your period, but it makes an appearance anyway. Perhaps it was earlier or later than expected, maybe welcome or unwelcome. Now, on the odd occasion that you have a one-off irregular cycle, this is generally not a cause for concern. However, for some, persistent patterns of irregularity mean it can feel impossible to know when aunt flow will arrive . If your periods are irregular or even absent…don’t ignore them! Finding out why can help prevent many short and long-term health implications - and can provide peace of mind! Remember that your menstrual cycle is a vital sign and critical indicator of your health, one we recommend you listen to . Without further ado, let's dive into what you need to know about irregular bleeding, commonly referred to as irregular periods.
So, what exactly is a “normal” period?
To understand irregular cycles, it is important that we first go back to the basics of the menstrual cycle.
What counts as my menstrual cycle?
A “normal” menstrual cycle is between 21 and 35 days . Now, if you are thinking “what does that even mean?”, we got you covered. No, we aren’t referring to the length of your period each month (we certainly hope that it isn’t that long!). The menstrual cycle refers to the first day of a period to the day before your next period. Simple, right? We should mention though, that while the “textbook” period is often considered 28 days, studies have actually shown that this is only the case for around 13% of people who menstruate . Meaning that if your menstrual cycle isn’t exactly 28 days each month, that is okay. For some, a 21-day cycle is normal and for others, a 35-day cycle might be normal. Each of us is unique. However, regardless of how long or short your menstrual cycle might be, your period should be arriving roughly within a couple of days of itself each month.
What is an irregular period?
Now that we have spoken about a regular or “normal” cycle, we can talk about an irregular one. Periods may be irregular if they occur less often than 21 days, more often than 35 days, or if they are unpredictable each month (if this is you, make sure you have those emergency period supplies handy!, such as a pair of Snuggs or backup pad/tampon) . Knowing your body and menstrual cycle here makes all the difference in recognising this. If you have had regular cycles previously, it is generally noticeable when your period shows up too quickly or later than usual. Perhaps one month your period occurs on day 28 and the next on day 37. That is irregular. To simplify things, an irregular cycle might mean that your period occurs infrequently, too frequently or unpredictably. When this happens for several months in a row, it is certainly time for a visit to the doc.
Is an irregular cycle always a cause for concern? Simple answer: no. It's not unusual to have the odd wonky month, and this is not the end of the world nor a reason to rush to the doctor. It is also normal for menstrual cycles to be irregular during certain times in a person's life, such as the onset of menstruation (menarche), the transition to menopause (perimenopause), the use of hormonal birth control, and post-pregnancy .
Causes of irregular periods
There can be many causes of an irregular cycle. Among the possibilities are:
- Extreme stressors: stress can sometimes make the brain uncertain about if it can adequately support a pregnancy and this then interferes with the communication between the brain and ovaries, making it harder to do so. Examples might be chronic illness, a loved one passing, changes in weight and extreme dieting or exercise 
- Polycystic ovary syndrome (PCOS): this is a complex condition that arises from hormonal abnormalities that can interfere with normal ovulation. It is characterised by menstrual irregularities, high levels of male hormones (testosterone) and multiple small follicles or cysts on the ovaries 
- Thyroid problems: the thyroid gland (located in the neck) creates thyroid hormones that work to control many of the body’s functions. Hypothyroidism or hyperthyroidism can result in the release of too few or too many thyroid hormones that directly affect the ovaries and menstrual cycle .
- Excess prolactin – prolactin is a hormone made from the pituitary gland that controls lactation (breast milk production) . High prolactin secretion can interfere with the normal production of hormones and alter or even stop ovulation. No ovulation = no period.
- Primary ovarian insufficiency (early menopause): this is when you are running out of eggs earlier than expected and so the ovary doesn’t have as many available in a given month 
A word on stress
Life is stressful (plus throw in a global pandemic, world conflicts and inflation), so let’s delve a little deeper into how stress might contribute to an irregular cycle [13, 14]. As we have established, your brain and ovaries are connected, and this is what controls the ongoings of your uterus. The brain, however, also needs to interpret signals from the rest of the body.
If it thinks that it might not be a good time to get pregnant, whether that be due to illness, infection, extreme emotional distress, intense exercise, eating restrictions and so on, it is going to stop sending out gonadotropin-releasing hormone (stay with us here), therefore the pituitary does not send out follicle-stimulating hormone (FSH), and you don’t ovulate . No egg grows. If no egg grows, there is no estrogen, no lining that develops, no progesterone and no period. Nothing happens.
If you think of this all from the point of evolution, it makes a hell of a lot of sense. If you are running from a bear, migrating across a country, or living in a famine or war (or any other huge stressor), the body doesn’t want to worry about supporting another life.
Tip: If you have missed a period or it is later than usual, don’t forget to take a pregnancy test. It never hurts!
If you have noticed a pattern of irregularity in your periods, you should see a healthcare provider.
- That is, if it is occurring more often than 21 days, less than every 35 days or it feels unpredictable…with no rhyme or rhythm in sight!
- Remember, if something doesn’t feel right when it comes to the body, it probably isn’t.
- Know that it is okay to go see a doctor. It is okay to ask questions. It is okay to be your own advocate.
Still have questions?
We are here to help. We provide educational advice, so if you aren’t sure about something, ask away!
Also, if you are not feeling comfortable about talking to your doctor yet, you could ask me. I do not provide medical help, but I could certainly pin point some basics of your concerns and guide you through ,...Ask Zoe
What to expect when going to the doctor for an irregular cycle
It can certainly feel daunting heading to the doctor about something like your period. But know that your doctor is there to help you and that there is no shame or judgement in talking about periods! When you go in, show your doctor your cycle history (a tracking app or diary can be helpful here) and mention any other changes or symptoms that you have been experiencing. This can help your doctor to solve the puzzle of what is causing your cycle irregularity. They will likely ask questions about your full health history, perform blood tests to check hormone and blood glucose levels and potentially a pelvic ultrasound of your uterus and ovaries.
Management of an irregular cycle
Treating an irregular cycle depends on, of course, the underlying reason behind why they are occurring. Management might include:
- Lifestyle changes (behaviour modification, diet, psychotherapy, and stress reduction techniques)
- Birth control pills or other medications
You can also take initiative to:
- Track your cycle: note the dates of your menstrual cycle and observe for irregularities
- Understand the normal physiology of the menstrual cycle
- Practice good sleep hygiene
- Address the root causes of your stress
- Take out some me-time. Listen to your body, what are you needing right now?
- Move your body!
- Seek support. Other healthcare providers such as psychologists, and dietitians can help you manage your cycle.
- Get an advocate. Navigating through all this alone can be, well, scary. Find support from someone you trust; they can even accompany you on your doctor’s visits!
Irregular menstrual cycles can be an indicator that something is going on in the body that needs to be addressed. It is important that you see a doctor to help determine the cause, protect your health and provide some peace of mind.