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Articles/The Facts About Irregular or Late Periods

The Facts About Irregular or Late Periods

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Dr Len Kliman Associate Professor
8 minutes mins read September 13th 2021
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What Are Irregular Periods?

When a woman stops getting her period this condition is called amenorrhoea. Primary amenorrhoea is when a young woman, usually an adolescent, never had her period, to begin with during puberty. Secondary amenorrhoea is when a woman who has had her period in the past stops getting her monthly period for three or more months.

Having a regular, moderately pain-free period each month is always a good indication that the female hormones are in balance and the reproductive system is working properly. Women with a regular cycle, and normal ovarian function release one egg about every 25 to 28 days. The average time between periods varies depending on the woman, especially during puberty and the peri-menopausal phase. However, most women will have their periods once a month providing they are in good health.

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Common Reasons For Missed & Irregular Periods


Pregnancy obviously stops the menstrual period. A period occurs when the uterine lining fails to implant a fertilised egg and comes away. Pregnancy can occur even if you are using contraception. You can still experience irregular spotting and symptoms of PMT, such as breast tenderness and cramps, which many women mistake as the beginning of their period. The only way this can be confirmed is to do a pregnancy test.

Stress Levels

Chronic stress or even short-term anxiety can wreak havoc with your hormone balance and can cause a missed period or an irregular cycle. Other severe stress conditions such as dieting, heavy exercise training or intense emotional events are all situations that can induce amenorrhoea or irregular periods.

Extreme Weight Loss and Low Body Weight

When your body mass index (BMI) falls below 18 you can start to miss your period due to having too little body fat. Body fat is vital in allowing you to have a regular cycle. One complication therefore of a low BMI is often a low circulating oestrogen level which is essential for body and especially bone health.


Although moderate exercise is very important for general health, mood regulation, sleep and maintaining a healthy body weight, too much exercise can also put excessive pressure on your adrenal, thyroid and pituitary glands. This can certainly cause irregular periods.

Poor Diet

A poor diet that is low in nutrients, antioxidants and probiotic foods, yet high in stimulants can affect the adrenal and thyroid glands. A diet high in intake of sugar, fats and artificial additives or pesticides, is linked with thyroid issues and adrenal fatigue that can raise cortisol. Excess cortisol hinders the optimal function of many of the other essential hormones such as the sex hormones.

Thyroid Disorders

Some reports show that thyroid disorders may be one of the leading causes of missed periods, with roughly 15% of amenorrhoea patients experiencing thyroid irregularities. Hyperthyroidism (overactive thyroid) is a thyroid condition that can cause light or absent periods. Hypothyroidism (under active thyroid) can cause heavy or irregular periods.

Being Unwell

Seasonal illnesses such as colds and the flu and certain viruses can all affect your cycle the same way that stress and anxiety can. If you have been prescribed a low-dose birth control pill, certain antibiotics may interfere with its absorption and result in irregular bleeding.

Ongoing Hormone Imbalances & Disorders

Polycystic ovary syndrome (PCOS) is a hormone imbalance in women that negatively impacts ovulation. PCOS results in altered levels of sex hormones, including oestrogen, progesterone and testosterone. This can in turn, result in many symptoms including an irregular menstrual cycle. As you are approaching the menopause (the average age is 51 in Australia) this can also account for missed periods or irregular periods. It is also possible to go through premature menopause prior to the age of 40 although this is more uncommon.

Birth Control Pill

The pill can make your periods lighter or cause you to miss periods or have less frequent period or even no periods at all. The contraceptive pill works by stopping ovulation and interrupting the normal menstrual cycle. If you forget to take your pill this may cause irregular bleeding which may resemble the beginning of your period, especially if you are taking a very low dosage of the contraceptive pill.

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Should I Be Concerned About My Period Being Irregular?

A missed or irregular period may be the first indication that you have a condition that needs medical attention. Bleeding during your cycle may be due to other causes, such as a cervical polyp, a vaginal skin disorder, a bacterial infection or pelvic inflammatory disease. Having an irregular cycle can also make it more difficult for you to get pregnant. There are tests that can be done to determine whether or not you are ovulating.

However, it is crucial to exclude an unlikely cancer of the cervix or uterus. If it has been more than three months since you have missed a period or you are experiencing constant irregularities with your cycle and you are concerned about your symptoms, it is important to follow this up with your doctor. You will most likely be screened for polycystic ovary syndrome, thyroid disease and other conditions that may be linked to irregular periods.

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Treatment For Irregular Periods

You will need to have a cervical screening test and most likely a pelvic ultrasound. The occasional irregular period or absent period per year is usually no cause for any concern, but any more than that then you should see your doctor make sure that a serious health condition is not the cause.

As the rule goes with most health concerns, if something doesn’t feel right, do not hesitate to ask your doctor for help. Dr Kliman is Certified in the Clinical Practice of Ultrasound by the Australian Society of Ultrasound in Medicine. To ensure you’re properly cared for during this time, get in contact with Dr Len Kliman.