Why Your Cycle Can Vary
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Why Your Cycle Can Vary
Have you noticed that your menstrual cycle has been changing lately? More people are noticing fluctuations in their cycle lately, and it’s no coincidence. Your cycle depends on a delicate balance of hormones and body systems, so when something changes, it can suddenly alter your cycle.
What is a ‘normal’ cycle?
Even a ‘normal’ cycle is more of a spectrum than a straightforward definition. You’ll often hear that a ‘normal’ cycle is 28 days long with a 5-day period. But according to medical guidelines, if you are an adult (not a teen) and don’t use hormonal contraception, a typical menstrual cycle is one that falls between 24-38 days long.
It’s not unusual for there to be some variation in your cycle length. When you look at your cycles over a period of a year, your cycle can vary by up to 9 days and still be considered ‘normal’.
For example, you might have a 28-day cycle, but have a busy, stressful month and notice you have a 25-day or 33-day cycle out of nowhere! That’s why it’s important to know why your cycle can fluctuate and when to investigate further.
There can also be some variation in the length of your period itself. A typical period will last 3-7 days, with anything longer than 8 days being considered abnormal. Again, this can depend on what is normal for you – if you consistently have a 3 day cycle and then all of a sudden have multiple 8 day periods, it is worth investigating further.
Why your cycle can fluctuate
So why can there be so much fluctuation in your cycle? There are many factors that can influence the process of ovulation and menstruation, which are the two key processes in your cycle.
Puberty
During the first few years of menstruation, it’s normal to have a fluctuation in the cycle length. This is because your body is adjusting to the increase in sex hormones. You also may not be ovulating every single cycle, which influences your cycle length.
For a teenager, the average length range is 21-45 days, and it’s not unusual for a cycle to be longer or shorter.
Hormone imbalances
If one sex hormone is thrown off balance for any reason, the others follow. Some of the common imbalances include:
Low progesterone (prevents ovulation)
High oestrogen
Low oestrogen
High testosterone (suppresses progesterone and prevents ovulation)
These can also contribute to the development of hormone disorders, so you want to get on top of them earlier rather than later.
To learn more about how to ease hormonal imbalances, check out this article.
Stress
One of the most common causes of a cycle fluctuation is stress. This can include physical stress (think a sudden change to routine or development of a health condition), mental stress and emotional stress. It’s also likely why many have noticed changes to their cycle recently.
When you’re under stress, you release stress hormones such as corticotropin-releasing hormone and cortisol. These can suppress production of sex hormones oestrogen and progesterone, and can even prevent you from ovulating.
Hormonal conditions
One of the reasons we want to monitor significant changes to your cycle is because it could indicate a hormonal condition. Changes to cycle length and/or period length can be a result of:
Polycystic ovarian syndrome (PCOS) – this can lead to a longer menstrual cycle and a variation in length of your period
Endometriosis – this can lead to a shorter menstrual cycle and a longer, heavier period
Fibroids – this can lead to a longer, heavy period
Pregnancy, ectopic pregnancy (when a fertilised eggs implants outside of the uterus) and miscarriage can also fall under the umbrella of hormonal conditions that alter the menstrual cycle.
Insulin resistance
Another hormone that can influence your menstrual cycle is insulin. If you have insulin resistance – when your body’s cells become resistant to insulin – it can increase your risk of longer and/or irregular periods.
Insulin resistance also ties in with elevated testosterone and PCOS, with 70% of women with PCOS also having insulin resistance. Suspect you might have PCOS? There are 10 signs to look out for – you can learn more here.
Thyroid issues
While we’re continuing the topic of hormones, we can’t forget the thyroid hormones. Thyroid hormone levels that are too high or too low can throw off your menstrual cycle.
An overactive thyroid is more likely to cause lighter, more irregular periods, whereas an underactive thyroid is linked to infrequent, heavier periods. But because of the complex relationship between the thyroid, sex hormones, stress hormones and insulin, thyroid imbalances can contribute to any change to your menstrual cycle.
Remember – if your doctor has told you that your thyroid is fine based on your TSH levels, this is not necessarily the case. TSH isn’t even a thyroid hormone – it’s a hormone produced by the brain to stimulate thyroid function. You want to check all of your thyroid hormone levels including T4, T3 and thyroid antibodies for a full picture of your thyroid function.
Birth control
Whether you’re using hormonal birth control or an alternative such as a copper IUD, it could influence the regularity of your cycle. Some of them will allow you to control when you have a breakthrough bleed (think the pill, ring or patch), and others can stop bleeding altogether.
However, birth control can also lead to uncontrolled changes to your cycle. They can lead to unpredictable or irregular bleeds, as well as changing the length of your menstrual cycle. You may also experience spotting at times other than your period/breakthrough bleed.
Low calorie diets
Have you been restricting yourself to 1500, 1200 or even 1000 calories? If so, your diet might be causing your menstrual irregularities.
A low energy intake in women can lead to the development of hypothalamic amenorrhea, or HA. HA can be caused by several factors, but one of the most common is a low-calorie diet. If you have a low body fat percentage, this can also contribute, but it can still occur in those who have a normal or high body weight if energy intake is low enough.
Excessive exercise
Another potential influence on your menstrual cycle is excessive exercise. This usually means too much high-intensity exercise and insufficient recovery time. It is more common among athletes, but it can occur if you are doing very intense exercise 5-6 days a week without enough recovery time.
Why does this happen? The most likely culprit is physical stress interfering with your hormone balance. Research has linked high cortisol levels to exercise-associated amenorrhea (when your period ceases due to excess exercise). Low body fat percentage can also play a role, although it is not always a contributor.
Alcohol and cigarette use
Heavy use of cigarettes and/or alcohol can affect the length and variation of your cycle. Smoking increases your risk of not ovulating and a shorter cycle, which could be due to the impact on liver function and/or inflammation. A heavy intake of alcohol is linked to greater fluctuations in the length of the menstrual cycle and the heaviness of periods.
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