The menstrual cycle is an important indicator of overall health. While many people have periods that occur at regular intervals, it is common for menstrual cycles to vary occasionally. However, periods that are consistently irregular, occur too frequently, too far apart, or stop unexpectedly may indicate an underlying health condition.
Irregular periods are common during certain stages of life, such as adolescence, after childbirth and during the transition to menopause. At other times, changes in the menstrual cycle should be assessed by a healthcare professional.
Understanding what is considered a normal menstrual cycle can help individuals recognise when medical advice is needed.
What Are Irregular Periods?
A menstrual period is considered irregular when there are significant changes in the timing, frequency or pattern of menstrual bleeding.
Irregular periods may include:
• periods that occur less than 21 days apart;
• periods that occur more than 35 days apart (for most adults);
• menstrual cycles that vary greatly in length from month to month;
• missed periods when pregnancy is not expected;
• unusually light or unusually heavy bleeding; or
• unpredictable bleeding between periods.Occasional variation is common and is not always a cause for concern.
What Is a Normal Menstrual Cycle?
Although every person is different, a typical menstrual cycle:
• occurs every 21 to 35 days in most adults;
• lasts between 2 and 8 days;
• follows a fairly predictable pattern over time; and
• may vary slightly from one month to another.For adolescents, menstrual cycles may be less regular during the first few years after menstruation begins.
Common Causes of Irregular Periods
Many factors can affect the menstrual cycle.
- Adolescence
During the first few years after the first period, ovulation may not occur regularly. This means cycles are often unpredictable until the body’s hormonal system matures.
- Pregnancy
A missed period is often one of the earliest signs of pregnancy.
Anyone who is sexually active and misses a period should consider taking a pregnancy test and seeking appropriate medical advice.
- Stress
Significant emotional or physical stress can temporarily affect hormone levels and delay or disrupt menstruation.
Examples include:
• examinations;
• bereavement;
• serious illness;
• major life changes; or
• chronic stress.- Weight Changes
Rapid weight loss, significant weight gain or inadequate nutrition may affect the hormones that regulate menstruation.
Very low body weight can cause periods to become infrequent or stop altogether.
- Excessive Exercise
High levels of physical activity, particularly when combined with inadequate energy intake, may lead to irregular or absent periods.
- Hormonal Conditions
Several medical conditions may affect the menstrual cycle, including:
• Polycystic Ovary Syndrome (PCOS);
• thyroid disorders;
• elevated prolactin levels; and
• premature ovarian insufficiency.Medicines
Certain medicines, including some hormonal contraceptives, may alter menstrual bleeding patterns.
Changes should be discussed with a healthcare professional if they are concerning.
Perimenopause
As menopause approaches, menstrual cycles often become irregular before periods stop completely.
This usually occurs between the ages of 45 and 55, although it can occur earlier.
When Are Irregular Periods Normal?
Irregular periods are more likely to be expected:
• during the first few years after menstruation begins;
• during pregnancy (when periods usually stop);
• while breastfeeding for some individuals;
• after stopping hormonal contraception while cycles return;
• during the transition to menopause; and
• following significant illness or temporary stress.Even during these times, persistent or concerning symptoms should be discussed with a healthcare professional.
When Should You Seek Medical Advice?
Medical assessment is recommended if:
• periods suddenly become irregular after previously being regular;
• periods stop for more than three months and pregnancy is not expected;
• cycles occur less than 21 days or more than 35 days apart consistently;
• bleeding between periods occurs regularly;
• periods are unusually heavy or prolonged;
• severe pelvic pain accompanies menstruation;
• pregnancy is suspected; or
• irregular periods are associated with excessive hair growth, severe acne or unexplained weight changes.How Are Irregular Periods Investigated?
A healthcare professional may ask about:
• menstrual history;
• medical history;
• medicines;
• sexual and reproductive history;
• recent stress or lifestyle changes; and
• family history.Investigations may include:
• pregnancy testing;
• blood tests to assess hormone levels;
• thyroid function tests;
• tests for iron deficiency if heavy bleeding is present;
• pelvic ultrasound; or
• other investigations depending on individual circumstances.Treatment
Treatment depends on the underlying cause.
Management may include:
• treating hormonal conditions;
• addressing nutritional deficiencies;
• managing stress;
• adjusting medicines where appropriate;
• hormonal contraception to regulate bleeding for some individuals; or
• treating any underlying medical condition.Many causes of irregular periods are treatable.
Frequently Asked Questions
- Is it normal to skip a period occasionally?
Yes. Occasional changes can occur because of stress, illness or other temporary factors. However, repeated missed periods should be assessed.
- Can stress delay a period?
Yes. Physical and emotional stress can temporarily affect the hormones that regulate the menstrual cycle.
- Are irregular periods always caused by PCOS?
No. PCOS is one possible cause, but many other medical conditions and life stages can also lead to irregular periods.
- Can birth control affect my periods?
Yes. Hormonal contraceptives may make periods lighter, less frequent, more regular or stop them altogether, depending on the method used.
- When should I be worried about irregular periods?
Seek medical advice if your periods suddenly change, stop unexpectedly, become very frequent, are accompanied by severe pain or heavy bleeding, or if you think you may be pregnant.
Key Messages
• Irregular periods are common and may occur for many different reasons.
• Adolescence, stress, pregnancy, breastfeeding and the transition to menopause can all affect the menstrual cycle.
• Persistent or unexplained irregular periods should be assessed by a healthcare professional.
• Many underlying causes, including hormonal conditions and thyroid disorders, can be effectively managed.
• The menstrual cycle is an important indicator of overall health, and changes should not be ignored if they are persistent or concerning.Knowledge Hub Series: Period Talk Uganda – Evidence-Based Menstrual Health Resources