Is Your Period Irregular? Understanding Changes in the Menstrual Cycle

For many women, a regular menstrual cycle is a familiar and expected part of life. When that rhythm suddenly changes and periods become unpredictable, delayed, or even absent, it can cause concern and confusion. While occasional irregularities may not be alarming, persistent changes often indicate that something deeper is going on within the body.

The menstrual cycle is regulated by a finely tuned system driven by the hypothalamus in the brain, the pituitary gland, and the ovaries. These systems rely on a physiologic equilibrium to ensure consistent communication among the processes that drive reproductive hormonal cycles. When physiologic balance is disrupted by illness, stress, overtraining, underfueling, supplements, or medications, this regulated sequence of hormonal function can become irregular or stop altogether. This change isn’t just a reproductive issue; it’s a signal that the body is responding to internal or external stressors or changes.

Understanding what influences the menstrual cycle can help identify when it’s time to seek support. Whether you’re an athlete, a busy professional, or simply someone noticing a shift in your cycle, paying attention to these changes is an important part of overall health.

1. Hormonal Imbalances

Hormones act as the body’s messengers, and their miscommunication can disrupt the menstrual cycle. Among the most common culprits is Polycystic Ovarian Syndrome (PCOS). This is a syndrome of findings which can include irregular or absent menstrual cycles, excessive hair growth, insulin resistance and elevated blood levels of testosterone and/or adrenal androgens (male hormones) that can disrupt normal ovulation. PCOS is also associated with a risk of metabolic syndrome, which is a constellation of elevated blood pressure, high cholesterol, and glucose intolerance (pre-diabetes or diabetes). 

Hyperprolactinemia, caused by the overproduction of prolactin, a hormone that is important for breastfeeding, can cause cycle irregularity or stop periods altogether. Lastly,  thyroid dysfunction, whether it be underactive (hypothyroidism) and overactive (hyperthyroidism) can lead to missed or irregular periods.

It’s critically important to identify these conditions if they exist because if they go untreated, it can have other health consequences that could impact, bone health, fertility, or cardiovascular health, among others. 

2. Low Energy Availability (LEA)

Another common cause of irregular or absent periods is an imbalance between energy consumption and energy expenditure. When there is insufficient nutritional intake to fuel the body’s physiologic processes and expenditure from exercise, this is called Low Energy Availability (LEA). Athletic women who train intensely for sport or recreation and women in physically demanding occupations (firefighters, police, military) are especially at risk. However, LEA can affect anyone who isn’t meeting their body’s energy demands. When energy is lacking, the body shifts into conservation mode, often turning off reproductive functions and, if prolonged, dialing down thyroid function as protective responses. When LEA is more severe or prolonged, it can impact bone health, cardiovascular health, mental health, sleep, and athletic performance. 

Energy imbalances can also be caused by disordered eating patterns. This ranges from restrictive diets to diagnosed eating disorders like anorexia or bulimia. Due to the extreme imbalances in energy intake and expenditure, these patterns, can severely disrupt reproductive and stress hormone production.

3. Psychological Stress

Stress, whether chronic or acute, has powerful effects on the endocrine system. Emotional strain from grief, marital discord, job loss, or even moving can interfere with hormonal signals that drive the menstrual cycle. The body does this as a survival strategy, protecting a potential pregnancy from unfolding in unstable circumstances.

While temporary irregularities due to stress often resolve on their own, ongoing stress can have longer-term effects on cycle regularity, mood and sleep disturbance, and overall health. Identifying sources of stress and developing healthy coping strategies is essential.

4. Medical Treatments and Health Conditions

Certain medical interventions can interfere with menstrual regularity. Treatments like chemotherapy and radiation can affect reproductive function and often suppress menstruation or result in sterilization. Surgeries involving the ovaries, uterus, or pituitary gland can have similar effects. Head injuries or tumors impacting the brain or pituitary gland can also disrupt the cycle. Women in these circumstances should be aware of potential menstrual changes and discuss them with their care team.

6. Life Stage Transitions: Pregnancy to Menopause

Missing a period is often the first sign of pregnancy, so a pregnancy test should be the first step if a cycle is late and pregnancy is a possibility. Similarly, when women are transitioning from reproductive age to menopause, hormonal shifts result in changing menstrual cycle patterns and ultimately, absence of menstrual cycles at the time of menopause. .

The usual age at which the transition from reproductive age to menopause begins is around 45 years old. Perimenopause refers to the period of time from when the reproductive window closes until the final menstrual period, typically 6-8 years later.. However, menopause onset can happen prematurely, before age 40, due to genetics, medical conditions, or other unknown factors. If you suspect premature menopause, it’s important to be evaluated, as this earlier than expected transition affects bone density, heart health, moods, sexual function and cognitive health.

Irregular menstrual cycles are more than a monthly physiological event. They’re the body’s way of signaling that something may need attention. From hormonal imbalances and fueling imbalance to stress and medical conditions, the causes are diverse and sometimes interconnected. Listening to these signals, rather than ignoring them, is crucial for maintaining long-term health and well-being. If your cycles have changed and you’re unsure why, it’s time to get clarity.

Dr. Carla DiGirolamo specializes in helping women understand and respond to changes in their menstrual and hormonal health. Schedule a consultation today to get expert insights into what your cycle is trying to tell you and how to take the next step toward balanced wellness.