Irregular Periods: 7 Reasons Why They Happen

Irregular Periods: 7 Reasons Why They Happen

Most healthy women of reproductive age get their period once in a menstrual cycle. The duration of the menstrual cycle differs from woman to woman. Most women, of course, have a cycle ranging from 24 days up to 34 days. It is important to know that it is normal for your menstrual cycle to be a bit shorter or longer than 28 days. So if you get your period a few days before or after the 28-day cycle, it is not a problem to be concerned about.

While it is expected to have a regular period once in every 28-day cycle, many women experience irregular periods. If you are getting irregular periods, you should be concerned. It is good to keep track of your menstrual cycle and see a doctor when needed. Mature women usually tend to have a more regular pattern for their menstruation. In order to calculate the length of your menstrual cycle, you should count the number of days between the starting days of your two consecutive periods.

In this blog from Captain Well, we will talk about the most common causes of irregular periods in women. Stay in the know with Captain Well.

Causes of Irregular Periods

You are expected to get your period once within 24 to 34 days. This is considered the norm. If you are getting irregular periods, there could be some underlying condition causing your erratic menstruation. It is important to find out what is causing your irregular periods so you can treat the condition as soon as possible. The sooner you know the underlying cause of your irregular periods, the better it is for your health.


During pregnancy, menstruation comes to a halt. You stop having periods for the entire duration of your pregnancy. If you have not gotten your period for more than 34 days, you could be pregnant.

Fortunately, pregnancy is very to diagnose, and you can do it all by yourself. You can buy a pregnancy test kit and test yourself for pregnancy. If your pregnancy test turns out negative, you can then check other reasons for your late period.


Hormonal imbalances can cause irregular periods. When experiencing a hormonal imbalance, you can get shorter or longer periods, or even miss a period in your menstruation cycle. One of the most common causes of hormonal imbalance is stress. Excessive stress which can happen due to stressful situations or heavy mental pressures can be the cause of your irregular or missed period.

Stress is a typical cause of irregular periods, especially because of the stressful lifestyle we all have. So, the next time you are going through an abnormal pattern of menstruation, you should take a look at the past few weeks to see if you have been in an excessive stressful situation. Perhaps this is the exact cause of your problem.


Intrauterine Devices, which are commonly known as IUDs, are widely used for birth control. There are two types of IUDs: hormonal, and non-hormonal IUDs. While the former releases a combination of sex hormones, the latter releases small doses of copper.

Right after insertion of IUDs, whether hormonal or non-hormonal, you will experience irregular periods, or heavy bleeding. So if your period irregularity started after IUD insertion, your IUD is causing your irregular periods.

In the long term, however, women who are using hormonal IUDs will likely experience irregular menstrual cycles. This is due to the presence of Levonorgestrel, the synthetic form of progesterone that is being released in your uterus. There is no difference in what type of hormonal IUD you are using. Milena, Liletta, Kyleena, or Skyla all cause irregular periods, and in some cases, no periods at all.

On the other hand, non-hormonal IUDs cause heavier bleeding or a longer period duration.


While the postpartum period itself is a special time for women and their period, there is another factor that has a huge effect on the menstrual cycle: breastfeeding. After childbirth, your body produces prolactin. Prolactin is a hormone produced by your brain that triggers breast tissue to produce milk for your newborn child. Whether you breastfeed or not after childbirth, you will still have high levels of prolactin in your system.

Prolactin causes infrequent periods and ovulation, leading to irregular menstruation. As a result, postpartum women usually experience irregular periods. If you are breastfeeding, you will not menstruate throughout your breastfeeding period. Even after you finish breastfeeding, you will still experience irregular periods until prolactin levels return to normal, pre-childbirth levels in your body.

Irregular periods after childbirth are completely normal. But if you think your irregular menstruation has lasted for too long, you should contact your OB-GYN for consultation.

Thyroid Problems

Your thyroid gland produces hormones that help control the menstrual cycle in women’s bodies. Thyroid problems refer to any disorder causing the gland to produce too much or too little hormones. These two thyroid disorders are called hyperthyroidism, or overactive thyroid, and hypothyroidism, or underactive thyroid.

Hypothyroidism and hyperthyroidism play an important role in menstrual cycle control. As a result, both thyroid disorders can cause irregular menstruation. Severe thyroid disorders can terminate your periods, resulting in no periods for many months. This condition, which is called amenorrhea, can even lead to an early menopause.

Fortunately, thyroid disorders are treatable. You should consult with a physician to seek treatment options for restoring optimal thyroid function.


While it may sound strange, exercising too much can cause irregular or missed periods. This condition happens to both professional female athletes and women who perform rigorous exercises. Almost 60 percent of female athletes experience signs of menstrual dysfunction throughout their careers.

If you regularly exercise and experience irregular periods, you must visit your OB-GYN as soon as possible. Irregular or missed periods can lead to some serious health conditions, such as vision changes and a decrease in bone density.

Taking Certain Medications

There are a lot of medications that can cause your menstrual cycle to change. You can find some useful information about the side effects of every medication in the instruction leaflet inside the medicine packet, or on the internet.

Aspirin and Ibuprofen are among common drugs that cause menstrual irregularity. Other medications that can also cause irregular periods include blood thinners, thyroid medications, antidepressants, and epilepsy drugs.

If you are on medication and experiencing menstrual irregularity, you should consult with your doctor to change your medication. Your doctor can prescribe a different kind of medication that does not interfere with your menstrual cycle.

When is an Irregular Period Concerning?

If the gap between two of your periods is more than 35 days or less than 21 days, or if your periods last for more than seven days, you should seek medical advice to find the underlying cause of your menstrual disorder. Your doctor will perform multiple tests to find the underlying cause of your irregular periods.

In this article, we discussed some of the most common causes of irregular periods. If you experience irregular periods for an extended period of time, you should visit a gynecologist as soon as possible to treat your menstrual disorder.