It can be unsettling when your period is late, especially if you know pregnancy isn’t the cause. For people assigned female at birth (AFAB), menstruation is a regular part of life, occurring roughly 500 times over a lifetime. While the average menstrual cycle is about 28 days, it can naturally vary from 21 to 45 days. Typically, your cycle establishes a predictable rhythm over time. So, when this rhythm is disrupted, there’s usually an underlying reason.
If you’re experiencing a late period and pregnancy is ruled out, you might be encountering amenorrhea. Amenorrhea isn’t a condition in itself but rather a symptom indicating an issue affecting your menstrual cycle. Whether you’re diagnosed with amenorrhea or simply noticing a sudden delay in your period, identifying the cause is crucial. Consistent irregular cycles can have long-term health implications, potentially leading to early menopause.
Here are common reasons for a late period that are not related to pregnancy:
1. Age-Related Cycle Changes
Irregular periods are common during two key phases of life: the initial years after menstruation begins and the transition towards menopause.
In the first few years of menstruation, cycles can be unpredictable. It’s not unusual for young individuals to experience irregular periods for up to six years. However, once your body establishes a consistent menstrual pattern, regularity should prevail for the next 35 years or more, interrupted mainly by pregnancies.
As you approach menopause, typically between 45 and 55, your body undergoes hormonal shifts that can lead to missed or late periods through several stages:
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Perimenopause: This transition period before menopause is characterized by hormonal fluctuations. Early perimenopause can manifest as inconsistent periods. In later perimenopause, you might experience intervals of 60 days or more between periods.
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Primary Ovarian Insufficiency (POI): Also known as premature ovarian failure, POI causes a decline in estrogen levels and ovary function cessation before age 40. Approximately 1% of individuals AFAB under 40 experience POI, leading to irregular or absent periods.
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Premature or Early Menopause: While the average age of menopause is 52, about 5% of people AFAB experience menopause earlier, between 40 and 45. Menopause occurring before 40, not due to POI, is termed premature menopause.
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Menopause: If you are over 50 and have gone a full year without menstruation, and amenorrhea isn’t diagnosed, you may have entered menopause without realizing it.
2. Stress and Its Impact on Your Cycle
Stress profoundly affects the body in numerous ways, influencing sleep, eating habits, and overall bodily functions. One significant impact of stress can be period delays. Research indicates a direct correlation between perceived high stress levels and menstrual cycle irregularities in individuals aged 20 to 40.
Chronic stress, persistent over time, can even cause periods to cease altogether. When stressed, the body produces more cortisol, a hormone that can disrupt the hypothalamus, the brain region regulating menstruation. When periods stop due to hypothalamic dysfunction, it is termed hypothalamic amenorrhea.
3. Polycystic Ovary Syndrome (PCOS)
Polycystic ovary syndrome (PCOS) is a hormonal disorder where individuals AFAB have elevated levels of male hormones (androgens). This hormonal imbalance often leads to cyst formation on the ovaries, disrupting ovulation.
If PCOS is the cause of your missed or irregular periods, you’ll likely experience other symptoms, including:
- Acne: On the face, chest, and back.
- Skin Darkening: Especially in skin folds (acanthosis nigricans).
- Excessive Hair Growth (Hirsutism): On the face, chin, or chest.
- Skin Tags: Painless flaps of skin on the upper body.
- Weight Issues: Weight gain or difficulty losing weight.
4. Weight Fluctuations and Eating Disorders
Body weight, both extremes of underweight and overweight, significantly influences menstrual cycles. Being underweight or having an eating disorder can disrupt ovulation and lead to irregular periods. Insufficient nutrient intake or absorption hinders hormone production needed to regulate menstruation. Rapid weight loss can also cause periods to stop entirely.
Conversely, being overweight also affects menstruation. A high body mass index (BMI) and obesity can alter hormone levels, specifically estrogen and progesterone, disrupting menstrual cycles. Weight gain and obesity are also linked to an increased risk and worsening of PCOS.
5. Hormonal Birth Control Methods
Many birth control methods utilize hormones to prevent ovulation. Starting, stopping, or changing birth control can cause hormonal shifts that disrupt your menstrual cycle. It may take up to three months or longer for periods to return to regularity after such changes.
Certain types of contraception can lead to lighter or missed periods throughout their use, including:
- Birth Control Implants: These release hormones consistently into the body.
- Hormonal Intrauterine Devices (IUDs): These primarily prevent fertilization but can also affect periods.
- Progestin-Only Pills (Mini-Pills): These may stop ovulation in some individuals.
If you use an IUD and experience complete period cessation, it’s crucial to consult your healthcare provider to rule out potential complications such as ectopic pregnancy, where pregnancy occurs outside the uterus.
6. Thyroid Gland Imbalances
Your thyroid gland produces hormones essential for growth and metabolism. Both an overactive thyroid (hyperthyroidism) and an underactive thyroid (hypothyroidism) can cause menstrual irregularities, including amenorrhea.
The thyroid’s role in metabolism also means that thyroid dysfunction can lead to weight changes (weight loss or gain), which, as discussed earlier, can further impact menstruation.
7. Chronic Health Conditions and Medications
Besides thyroid disorders, other chronic diseases can interfere with menstruation, such as:
- Celiac Disease
- Diabetes
- Pelvic Inflammatory Disease (PID)
Even if a disease itself doesn’t directly affect menstruation, certain medications can cause period delays or absence. Medications associated with menstrual cycle changes include:
- Anti-epileptics
- Anti-psychotics
- Antidepressants
- Chemotherapy drugs
- Thyroid medications
When to Seek Medical Advice for a Late Period
The first step when you miss a period should be to rule out pregnancy. If a pregnancy test is negative, or if you haven’t been sexually active since your last period, it’s important to consult your healthcare provider. They can evaluate your symptoms, review your medical history, and recommend further testing if necessary.
Fortunately, most underlying causes of late or missed periods are treatable or manageable. Tracking your menstrual cycles and proactively addressing any delays can help ensure timely diagnosis and treatment.
