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When your menstrual cycle falls outside of the normal range, do consult a doctor to see if any underlying disorder might be the reason for it. — TNS

Why is my period late (when I’m not pregnant)?

Are you concerned about a late period, but you know, or have checked that, you aren’t pregnant?

Aside from pregnancy, hormonal imbalances or serious medical conditions can cause missed or late periods. You may also experience irregular periods when your menstrual cycle first begins, as well as when you are transitioning to menopause (i.e. during peri-menopause). As your body transitions, your cycle may become irregular.

So, how much delay is normal when it comes to periods? A healthy menstrual cycle can range from 21 to 40 days for those who haven’t reached menopause. Women usually have their period approximately once every 28 days. One of the following reasons may explain why your period does not fall within this range.

Low body weight

When a woman’s body weight drops to a level that is too low for her unique needs, it can disrupt hormonal balance and lead to menstrual irregularities. This condition is known as hypothalamic amenorrhoea, which refers to the absence of menstrual periods due to dysfunction in the hypothalamus, the part of the brain that regulates reproductive hormones.

In cases of low body weight, the body may perceive a lack of energy stores as a sign of inadequate resources for supporting a pregnancy. Consequently, the hypothalamus reduces the production of gonadotropin-releasing hormone (GnRH), which in turn affects the secretion of luteinising hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland.

This disruption leads to irregular or absent ovulation, and subsequently, irregular or absent menstrual periods. Without ovulation, pregnancy will not occur naturally, and is also difficult to achieve artificially. While it’s not a guarantee, restoring a healthy body weight and addressing any underlying causes of low body weight can often improve fertility outcomes.

High body weight (obesity)

Adipose tissue (fat cells) can produce and store oestrogen. In individuals with obesity, the excess fat tissue can result in higher levels of oestrogen in the body. This hormonal imbalance can interfere with the normal hormonal signals involved in regulating the menstrual cycle, leading to irregular or heavy periods.

Obesity is closely associated with an increased risk of developing polycystic ovary syndrome (PCOS). Women with obesity and PCOS often experience irregular periods, oligomenorrhoea (infrequent periods), or even amenorrhoea (absence of periods), due to disrupted ovulation.

Birth control

While birth control pills aim to provide hormonal stability, it’s worth noting that changes in hormone levels can still occur when starting or stopping the pills. It’s common for the body to take some time to adjust to the hormonal changes introduced by birth control pills, which may cause irregular bleeding or spotting during the initial months of use.

The effects of birth control pills on menstrual regularity can vary among individuals. Some women may find that their periods become more predictable and lighter, while others may experience changes such as breakthrough bleeding or irregular cycles.

Factors such as the specific formulation of the pill, individual hormone levels and overall health can influence how a person responds to the medication.


Being either overweight or underweight can cause disruption to your menstrual cycle. — AFP

The menstrual cycle is regulated by a complex interplay of hormones, and when the body experiences stress, it can disrupt this delicate balance. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, which releases a cascade of stress hormones such as cortisol and adrenaline.

These stress hormones can interfere with the production and regulation of reproductive hormones, such as oestrogen and progesterone, which are essential for maintaining a regular menstrual cycle. Not all women will experience disruptions in their menstrual cycles due to stress.

However, for those who are more sensitive to stress or have pre-existing hormonal imbalances, the impact of stress on menstrual regularity may be more pronounced.

Thyroid issues

When thyroid function is disrupted, it can lead to imbalances in reproductive hormones, which can subsequently affect the regularity of menstrual cycles. Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormones.

Insufficient levels of thyroid hormones can disrupt the balance of reproductive hormones, such as oestrogen and progesterone, leading to menstrual irregularities. Hyperthyroidism refers to an overactive thyroid gland, producing an excess of thyroid hormones.

Excessive levels of thyroid hormones can speed up the body’s metabolism and lead to irregular menstrual cycles. Women with hyperthyroidism may experience lighter or shorter periods, irregular cycles, or even amenorrhoea.

Women with PCOS have a higher risk of thyroid disorders, and thyroid dysfunction can further exacerbate menstrual irregularities in PCOS. It’s important to address both conditions when managing menstrual regularity in these cases.

Polycystic ovary syndrome (PCOS)

PCOS is characterised by imbalances in reproductive hormones, the presence of small cysts on the ovaries, and various symptoms that can affect multiple aspects of a person’s health. Menstrual irregularities are a common feature of PCOS.

One of the primary menstrual irregularities associated with PCOS is oligomenorrhoea. Women with PCOS may have fewer than eight menstrual cycles per year or experience cycles that are longer than 35 days.

This irregularity is often a result of anovulation, where the ovaries do not release an egg during the menstrual cycle. In some cases, PCOS can lead to amenorrhoea, which is the absence of menstrual periods for three or more consecutive months. Amenorrhoea in PCOS is typically a result of chronic anovulation.

The hormonal imbalances and disrupted ovarian function in PCOS can prevent the normal development and release of eggs, leading to absent periods. Some individuals may also experience heavy or prolonged menstrual bleeding when periods do occur.

Premature ovarian insufficiency (POI)

One of the main characteristics of POI is irregular or absent menstrual periods. Women with POI may experience skipped periods, longer or shorter cycles, or even complete cessation of periods. This irregularity is primarily due to decreased ovarian function, which leads to a decline in hormone production, including oestrogen and progesterone.

Anovulation is common in POI. With reduced ovarian function, the ovaries may not release eggs regularly or at all, resulting in anovulatory cycles. Without ovulation, menstrual cycles become irregular or absent. Women with POI often experience symptoms similar to those of menopause.

These can include hot flashes, night sweats, vaginal dryness, mood changes and sleep disturbances. These symptoms may contribute to menstrual irregularities and impact overall menstrual regularity.

What to do

If you are experiencing irregularities in your menstrual cycle, it’s advisable to take the following steps:

  • Track your menstrual cyclesStart keeping a record of your menstrual cycles, noting the dates when your periods start and end, as well as any changes in flow or other symptoms you may experience.Tracking your cycles over a few months can help you identify any patterns or irregularities.
  • Consult with a healthcare professionalIf you notice persistent irregularities in your menstrual cycle, it’s recommended to consult with a healthcare professional, such as a gynaecologist or your general practitioner/family doctor.They can evaluate your specific situation, discuss your medical history, and perform any necessary examinations or tests to determine the underlying cause of the irregularities.
  • Undergo diagnostic tests if necessaryDepending on your symptoms and medical history, your healthcare professional may recommend diagnostic tests, such as blood tests to assess hormone levels, ultrasound imaging of the reproductive organs or other investigations to determine the cause of your menstrual irregularities.
  • Follow recommended treatmentTreatment for menstrual irregularities depends on the underlying cause identified by your healthcare professional.It may involve lifestyle changes, hormonal therapy, medication or other interventions.Follow your healthcare provider’s recommendations and adhere to the prescribed treatment plan.

Remember that everyone’s body is different, and occasional variations in menstrual cycles can be normal. However, if you notice persistent or concerning irregularities, it’s always best to consult with a healthcare professional to determine the underlying cause, and receive appropriate guidance and treatment.

By Datuk Dr Nor Ashikin Mokhtar
Published in Star Newspaper, 19 Jun 2023

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