Irregular periods: Causes and how to manage

What are irregular periods?

When we talk about irregular periods, we’re often referring to irregular cycles, meaning menstrual cycles that vary in length. Every cycle starts on the first day of your period, so shifts in cycle length will cause your periods to arrive either later or earlier than you might expect. 

A 28-day cycle is often considered the norm, but in a study of over 600,000 cycles using data from Natural Cycles (one of the largest studies of its kind), we found that only 13% of cycles were 28 days long. Perhaps more importantly, cycle lengths vary from person to person [1]. There’s actually a pretty large range that is “normal”: cycles that last between 21 and 35 days are usually considered regular [2].

However, cycle length is only part of the story. Irregular periods can also refer to the bleeding itself, for example, if you bleed much more than usual. In short, irregular periods include [2]:

• Menstrual cycles that are shorter than 21 days or longer than 35 days
• If your cycle varies by more than 7-9 days 
• You don’t get a period for three months 
• Your periods last longer than seven days
• If you bleed much more or less than usual during your period
• Bleeding or spotting that happens outside of your period
• If you have severe pain during your period

Reasons for a late period, missed period, or irregular period

Often, the first thing that comes to mind when your period is late is that you’re pregnant. However, pregnancy is not the only thing that causes late periods. To understand why our cycles vary in length, let’s take a step back and look at the basics of the menstrual cycle. 

Each cycle consists of two phases, the follicular phase and the luteal phase. The follicular phase starts on the first period day and during this phase, the body is preparing for ovulation. After ovulation, the luteal phase starts as the body prepares for pregnancy (which happens if the egg is fertilized by sperm). If the egg isn’t fertilized, the luteal phase ends when your next period starts.

The length of a menstrual cycle largely depends on when ovulation happens. The luteal phase usually lasts about two weeks (even though the exact length varies between individuals) and is pretty stable in length. So, once you ovulate, you can expect your next period after about two weeks. In short, most changes in cycle length are due to ovulation happening earlier or later than usual. Pretty cool, right?

And what about missed periods? If conception happens and you become pregnant, missing a period is a common first symptom. Periods can also stop for other reasons, and if you don’t get a period for more than three months (and are not pregnant), it’s called “amenorrhea”.

What causes irregular periods?

The causes of irregular periods are many and varied. These range from stress to different medical conditions. Some of these are easier to predict or manage than others, but it’s still useful to be aware of what might be affecting your cycle from one month to the next. 

Medical conditions that cause irregular periods

Some medical conditions can affect our cycles and hormones, and these may also cause irregular periods.

• Polycystic ovary syndrome (PCOS): Irregular periods are a common symptom of PCOS since this condition leads to higher androgen levels (a type of hormone) that can disrupt or stop ovulation from happening.
• Endometriosis: This condition causes uterine tissue to grow outside the uterus, and it can cause heavy and painful periods.
• Primary ovarian insufficiency (POI): A condition where the ovaries aren’t working as they should, which leads to irregular ovulation and, in turn, irregular periods. POI can also cause infertility [3].
• Thyroid conditions: The thyroid is involved in regulating the hormones that govern the menstrual cycle (estrogen and progesterone), so thyroid conditions can affect our cycles. An underactive thyroid (hypothyroidism) is linked to irregular periods and heavier bleeding, while an overactive thyroid (hyperthyroidism) can result in lighter-than-normal periods [4].
• Endometrial cancer: Cancer in the uterine lining (endometrium) can cause changes in bleeding patterns, like heavier periods or bleeding outside of your period [2]. This is rare, but it’s always good to talk to your doctor if you experience any type of unexplained bleeding.

Birth control and irregular periods

Since most hormonal birth control works by stopping ovulation (including the pill or hormonal IUDs), it’s common to not have a period while taking them. You might experience a withdrawal bleed instead, for example during the placebo week if you’re on the pill. This bleeding can be quite sporadic and, unlike your period, it doesn’t mark the start of a new menstrual cycle.

It’s worth knowing that when you stop taking hormonal birth control, you might experience irregular periods for up to a year while your body readjusts. If you don’t want to take synthetic hormones, there are also many hormone-free birth control options available. 

Lifestyle factors that can cause irregular periods

There are a whole bunch of lifestyle factors that can impact our cycles and lead to irregular periods. Some of these may temporarily delay ovulation in a certain cycle, while others can cause longer-lasting changes, these include:

• Low or high BMI: There’s research to suggest that both obesity and being underweight are linked to a higher risk of irregular periods, especially in younger women and teenagers [6]. However, more studies are needed to understand exactly how weight affects the menstrual cycle in adults.
• Stress: Stress can affect our hormones and high stress levels can affect the menstrual cycle and lead to irregular periods [7].
• Smoking: Research has found that smoking increases the risk of irregular periods, and it may also lead to early menopause [8].
• Excessive exercise: While exercise on its own usually doesn’t cause irregular periods, excessive training while not eating enough food can make cycles irregular or even make your periods stop [9].

Other reasons for irregular periods

Irregular periods are common at the start and end of our fertile years. When we first get our periods, they are often irregular until a couple of years after puberty. Periods also become irregular again around menopause until they stop altogether.

Irregular periods are also common after pregnancy since our hormone levels are different during this time. Breastfeeding affects our periods since the hormone that stimulates milk production (called prolactin) can stop you from ovulating or make this more irregular.

Even pregnancies that don’t result in birth can affect our cycles, so periods can be more irregular for a while after a miscarriage or abortion. Certain medications, like blood thinners, or infections like pelvic inflammatory disease can also lead to irregular periods or changes in bleeding [2]. 

When should you see a doctor about irregular periods?

Menstrual cycles vary naturally, and it’s normal to get your period on a different day each month. Our bodies aren’t machines and some changes from cycle to cycle are expected, and even if you have an unusual cycle now and again, it’s usually nothing to be concerned about. 

However, it’s good to keep note of changes in your cycle since, in some cases, it can be a sign of something more serious. You should always speak to your doctor if:

• You usually have regular periods that suddenly become irregular
• You have irregular periods and are struggling to get pregnant
• Your periods last longer than seven days or are very heavy
• You experience bleeding between your periods or after menopause
• Your periods are irregular, and you have other symptoms like fatigue, hair growth on your face, acne, or weight gain
• You have severe pain, nausea, or vomiting during your periods

How are irregular periods diagnosed?

Having an irregular period is not a diagnosis in itself, but it can be a symptom of an underlying condition that your doctor can diagnose. This is also the first step to determining if any treatment is needed.

Together with your doctor, you’ll walk through your medical history. You’ll be asked to describe what your periods are usually like, for example, how much you bleed, how often you get them, and if anything has changed over time. It can be helpful to track your cycles so that you can share the information during your appointment.

Your doctor may also conduct a physical exam, like a pelvic exam, an ultrasound, a biopsy, or imaging like an MRI scan. Depending on your symptoms, you may also get some other tests done.

How are irregular periods treated?

Because irregular periods can be a symptom of so many different things, the treatment will depend on the underlying cause. It’s always good to discuss your options with your doctor if you’re concerned. Treatment may include [2]:

Medication

Medication is often the first step in treatment, and options for irregular periods include:

• Hormonal birth control can be prescribed to help manage irregular or heavy periods due to PCOS, endometriosis, or fibroids, and they prevent pregnancy at the same time. Because the hormones often stop ovulation, birth control can make bleeding more regular or even stop it completely. There are combined birth control options that contain both synthetic estrogen and progestin (like the birth control pill), as well as progestin-only options (like the mini pill) for those who aren’t able to take anything containing estrogen.

• Hormone replacement therapy (HRT) means that you take additional hormones, often a combination of estrogen and progestin, and it helps relieve symptoms if you have irregular periods due to perimenopause. HRT can also be used to treat primary ovarian insufficiency. There are some risks associated with this treatment, so it’s important to go through the risks and benefits with your doctor.

• Tranexamic acid is a type of medication that’s used to treat heavy menstrual bleeding.

• Pain relievers can be used to treat painful periods. You can often find over-the-counter options, but your doctor may also prescribe medications if needed. 

• Gonadotropin-releasing hormone agonists can be used to treat fibroids by reducing their size, and they also stop the menstrual cycle. However, this medication can only be used for less than six months, and the effect is temporary. 

Surgery

If medication doesn’t help, your doctor may recommend surgery as a next step for certain conditions. There are a couple of different types of surgery that can be used to treat irregular periods [2]:

• Endometrial ablation: A procedure that destroys the lining of the uterus, which means that you’ll bleed much less during periods or not at all. You need to use birth control at all times after having this procedure because there’s a high risk of complications if you were to get pregnant.
• Fibroid treatments: There are several surgical treatment options for fibroids. For example, you can have surgery that blocks the blood flow to the uterus so that fibroids can’t grow, ultrasound surgery that destroys fibroids with ultrasound waves, or a myomectomy which is surgery to remove fibroids.
• Hysterectomy: A hysterectomy means that the uterus is removed completely, and this can be used to treat conditions like adenomyosis, fibroids, or cancer if other treatments haven’t worked. You’ll no longer have any periods after a hysterectomy. 

Managing irregular periods

If you have irregular periods that aren’t caused by any underlying condition that requires medical treatment, some changes to your routine may help make your cycles more regular.

Most of us experience periods of high stress from time to time; it’s part of life and that’s okay. However, stress can affect our cycles and make them more irregular, so it’s also important to take time for recovery — both for your body and mind. 

Weight can be a factor in irregular periods, and our cycles can also be affected by weight gain or loss. Eating a healthy diet with a good balance of carbs, protein, and fiber, getting enough sleep, and exercising regularly are good for promoting overall health. It’s also always a good idea to speak with your healthcare provider before changing your diet if you have any questions. 

You may also find it useful to use a cycle-tracking app to record the length and regularity of your periods. This can help you anticipate changes to your cycle and help you manage other symptoms such as PMS or period pain. Natural Cycles not only records cycle length and symptoms but, as a temperature-based app, it can confirm and predict ovulation too. This in turn can help you understand your body and your unique cycle even better.

What to do when periods are irregular?

While some of us may not be too bothered by irregular periods, for others, they can be hard to navigate. Not knowing when your period might start can be stressful, and symptoms like pains or heavy bleeding can also affect everyday life. Even if we haven’t really paid attention to irregular periods before, we might start noticing them more when we start trying to get pregnant.

Trying to get pregnant with irregular periods

There are only six days in each cycle when you’re able to get pregnant — this is called the fertile window. For those with irregular cycles, it can be harder to predict this fertile window since it changes from one cycle to the next. Because of this, a common recommendation is to have sex every couple of days throughout every cycle [10]. 

There are also a few ways of narrowing down the fertile window while trying to conceive. For example, ovulation tests can be a useful tool to predict ovulation. These tests detect a surge of luteinizing hormone in urine up to 48 hours before ovulation (they do not, however, confirm ovulation has happened). If you get a positive ovulation test, it’s a good time to get under the sheets.

You can also consider tracking cervical mucus during your cycles. During the most fertile days, you might notice so-called egg white cervical mucus — this helps sperm survive longer in the female reproductive system and reach the egg. However, discharge varies between individuals, and without clinical training, predicting fertility from cervical mucus alone can be extremely difficult.

Another option for finding the fertile window is tracking your basal body temperature. The hormone progesterone causes a slight increase in body temperature after ovulation, which can be measured with a special basal thermometer. However, the rise in body temperature is only visible after the fertile window has closed. This is where predicting ovulation comes in. 

Tracking ovulation and irregular cycles with Natural Cycles

Ovulation can be a tricky thing to track and predict, especially with irregular cycles where the ovulation day changes a lot. The Natural Cycles algorithm uses your body temperature to learn the pattern of your unique cycle. Using the ovulation data from your cycles, the algorithm can predict when ovulation will happen and which days you’re most likely to be fertile. Knowing your fertile window allows you to either plan or prevent pregnancy depending on your goal.

When using NC° Plan Pregnancy, the fertile days are shown as a scale of red colors, with a darker red for days when conception is most likely. For those using NC° Birth Control to prevent pregnancy, Natural Cycles is just as effective for irregular and regular cycles (93% effective with typical use and 98% effective with perfect use). 

If you’d like to know more about your body, Natural Cycles is a great way to learn the pattern of your unique cycle. The NC° app can help you keep track of any cycle irregularities, and you’re also able to log many different symptoms so you know what to expect during your cycles. Why not see if it’s the right fit for you?