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Irregular periods can be caused by many factors, including hormonal imbalances, lifestyle, and various health conditions. Common causes include changes in estrogen and progesterone, PCOS, stress, thyroid disease, significant weight changes, intense exercise, birth control, pregnancy, breastfeeding, perimenopause, and uterine problems such as fibroids or polyps.
Hormonal imbalances can affect ovulation, making periods irregular or absent. Stress and strenuous exercise can disrupt the hypothalamus and affect hormone production. Birth control can either stabilize or alter the cycle, depending on the method.
Symptoms like irregular periods can be caused by many different factors, from lifestyle to birth control and various health conditions that can affect how your menstrual cycle behaves. Here are ten common reasons why your period may be irregular and how you can test your hormones to get answers to any underlying causes of your symptoms.
1. Hormonal Imbalances
Hormonal fluctuations in estrogen and progesterone can affect how regular your period is. Fluctuating hormone levels are especially common in teenagers, as their hormonal systems are still stabilizing, and in women in perimenopause, where hormone production naturally changes. Hormonal conditions such as hypothalamic amenorrhea, prolactinoma, luteal phase defect and hypogonadotropic hypogonadism can also lead to absent or irregular menstruation.
2. Polycystic ovary syndrome (PCOS)
PCOS is one of the most common causes of irregular menstruation and is due to elevated levels of androgens (male sex hormones) and insulin resistance. This often leads to ovulation occurring less frequently or completely absent, which in turn can cause long menstrual cycles or the absence of menstruation for several months. Women with PCOS may also experience symptoms such as increased body hair, acne and weight gain.
Get insight into your hormones, we offer blood tests that analyze your estrogen and progesterone levels and hormones that can provide an indication of conditions such as PCOS.
3. Stress
When the body is exposed to prolonged stress, levels of cortisol (our “stress hormone”) increase, which can disrupt communication between the hypothalamus, pituitary gland and ovaries. When this happens, menstruation can be delayed, absent or irregular. Chronic stress can also negatively affect ovulation and in some cases lead to secondary amenorrhea, where menstruation disappears completely for a longer period.
4. Thyroid diseases
Thyroid diseases such as both hypothyroidism (underfunction) and hyperthyroidism (overfunction) can affect whether the menstrual cycle is regular or not:
- Hypothyroidism can cause longer and heavier periods, often accompanied by fatigue, chills and weight gain.
- Hyperthyroidism can lead to shorter, lighter or no periods at all, as well as symptoms such as sweating, palpitations and weight loss.
Thyroid hormones play an important role in regulating metabolism and also affect sex hormones that control ovulation. Gain insight into your thyroid hormones with our thyroid test that analyzes T3, T4 and TSH.
5. Severe weight loss or weight gain
Extreme weight loss, especially if it occurs rapidly or leads to a very low body fat percentage, can disrupt hormone production and lead to a lack of menstruation (amenorrhea). The reason for this is that the body goes into an energy-saving mode and reduces the production of gonadotropins that are important for ovulation. On the other hand, severe weight gain, especially in the case of insulin resistance or high estrogen production from fat tissue, can disrupt the menstrual cycle and contribute to irregular or absent ovulation.
6. Intense exercise
Excessive physical exercise, especially in combination with low calorie intake, can affect the hypothalamus and reduce the production of gonadotropin-releasing hormone (GnRH), which can lead to a lack of ovulation. This is common in elite athletes and people with very low body fat.
7. Contraceptives
Hormonal contraceptives such as birth control pills, hormonal IUDs, injections and implants affect the body's natural hormone production and can cause changes in the menstrual cycle:
- Combined birth control pills and hormonal patches can make periods more regular but can also cause breakthrough bleeding.
- Penal injections and hormonal IUDs can cause periods to become lighter or stop altogether.
- Copper IUDs can instead cause longer and heavier bleeding.
8. Pregnancy or breastfeeding
One of the most common causes of missed periods is pregnancy. Early pregnancy can sometimes cause light bleeding that can be mistaken for an irregular period. After giving birth, breastfeeding can affect the menstrual cycle, as prolactin – the hormone that controls milk production – inhibits ovulation. It is common for women who breastfeed to not get their periods back until breastfeeding is reduced or stopped completely.
9. Perimenopause (the menopause)
During perimenopause, which usually begins in the 40s and 50s, estrogen and progesterone levels begin to fluctuate, which can lead to irregular periods. Periods can be shorter or longer, heavier or lighter, and sometimes skip a month or more. This phase usually lasts for several years before menstruation disappears completely at menopause.
Do you want to gain insight into your hormones and whether they may be related to menopause? Read more here about the packages Menopause test and Menopause test and consultation with a doctor.
10. Uterine problems
Various changes in the uterus can affect menstruation:
- Myomas (benign fibroids) can cause heavy, prolonged or irregular bleeding.
- Polyps in the uterine lining can cause breakthrough bleeding or heavier periods.
- Endometriosis, which is a condition in which the lining of the uterus grows outside the uterus, can cause painful and irregular bleeding and affect fertility.
When should you seek medical attention?
Seek medical attention if you have recurring irregular periods, especially if they are also accompanied by other symptoms such as pain, heavy bleeding or hormonal changes. Blood tests to analyze hormone levels (e.g. estrogen, progesterone, LH, FSH, TSH, and prolactin) or ultrasound of the ovaries and uterus can provide important information about your hormonal balance and any underlying conditions.
