When is Missing my Menstruation abnormal?

Each menstrual cycle starts on the first day of your period and continues all the way until the next period comes, this cycle is often about 28 days long but can vary between women from 21 to 35 days long. You would typically expect the next period to start between 1-4 days earlier or later than expected if it is regular or if the period happens unpredictably throughout the month, it would be considered irregular menses.

Women can occasionally experience irregular menstrual cycles, or even skipped cycles at times. We term this as amenorrhoea, or more specifically secondary amenorrhoea. This varies from woman to woman, which is why it is defined as the cessation of regular menses for 3 months or cessation of irregular menses for 6 months.

What does this mean?

It actually means it can be completely normal to miss your period for up to 3 months, which means you can opt to monitor it and see if it does eventually resume the normal monthly cycles.

When should I worry about missing my periods?

So if you typically have quite regular periods and you have missed beyond 3 cycles, consider seeking out medical help to see whether there are possible underlying medical conditions that might be triggering. This will be covered in more detail below. For women with irregular menses, consider monitoring for 6 months, as it can be unpredictable when to expect your next cycle to come. Beyond that, if your menses has not returned, consider seeing a doctor as well.

What are some of the causes of missing my menses that could just be lifestyle-related?

If you happen to miss your period for a month or 2 and are considering holding out on seeing a doctor, think through whether any of these might be the cause for it.


The most common cause to consider initially especially if you are in a reproductive age group would be whether pregnancy could be in the cards. If you do not use contraception and are currently sexually active, then there is always that possibility. This can be checked very easily with a over the counter urine pregnancy kit from your nearby pharmacy. The best and earliest time to check this would be around the time you would expect your menses to come (and yet it hasn't).


If you are approaching the menopausal age group around 45-55 years of age, it is possible you are entering a perimenopausal period, which is the year just before you hit menopause. During this period, your menses can become fairly irregular, sometimes missing months on end, only for it to return only sometimes. Often, there may be other associated menopausal symptoms like hot flushes, night sweats, vaginal dryness, headaches, mood swings and reduced libido.


After delivering a child, breastfeeding post-partum does stop the menses from returning. The effect of breastfeeding on ovulation is variable in different women so some women do sometimes experience their periods despite breastfeeding. However, if you recently just delivered a child, you may not expect your menses to return so quickly, especially if you are breastfeeding.

Stress Mental stress can cause mild hypothalamic dysfunction, which is an area of your brain which controls the hormones than regulate your menstrual cycle. This is often temporary and can self resolve after the stress level decreases. However, if the absence of menses goes beyond 3 months, this might require further evaluation apart from just attributing it to stress levels.

Weight changes

Eating disorders such as anorexia or bulimia, which results in a very low body weight can trigger amenorrhoea or cessation of menstruation. Often nutritional supplementation and weight gain is needed for the menses to resume again.

Excessive exercise

Strenuous exercise may cause menstrual abnormalities, including amenorrhea. This has often been associated with low bone mineral density (predisposing to osteoporosis) and increased risks of stress fractures. Reducing the intensity of your workout or increasing your body weight, can help with resumption of usual menstrual cycles and reduce risk of osteoporosis.

Birth control pills

It is possible that oral contraceptive pills can cause breakthrough bleeding as a side effect and occasionally, cessation of menstruation as well. Often times, it would be useful to monitor the menstrual cycles after starting on the pill and see if the amenorrhoea persists, as some of birth control pill side effects tend to get better with time. If the menses still fails to return, consider seeing a doctor to see whether there are other possible more dangerous causes.

What are some medical conditions that could cause me to miss my menses?


There are some medications that can cause the failure of menses to return, such as anti-psychotics, anti-depressants, anti-hypertensives. More commonly though, some gastric medications prescribed for vomiting and reflux like metoclopramide, domperidone, ranitidine, cimetidine can cause amenorrhoea as well. So think back about any recent prescriptions or consumption of medications that could be a possible cause.

Polycystic Ovarian Syndrome (PCOS)

PCOS is a condition that causes the female body to produce a higher amount of androgen, resulting in anovulation, which is the lack of ovulation. It is characterized by multiple small cysts to form in the ovaries when follicles do not rupture to release eggs during normal ovulation in menstrual cycle. Other associated symptoms also include excessive facial hair growth, acne, weight gain and infertility. There is also a correlation with increased risk of diabetes so this is often checked in women with suspected PCOS and treated if needed.

Premature ovarian failure

This refers to early menopause or when menopause occurs before 40 years old. The ovaries stop working and this results in low estrogen levels, mimicking a menopausal state. This gives rise to the same menopausal symptoms mentioned earlier like hot flushes, night sweats, vaginal dryness, headaches, mood swings and reduced libido. However, this occurs earlier than expected and if considered, needs to be further investigated with a medical professional.

Thyroid problem

Hypothyroidism or low thyroid levels can sometimes lead to amenorrhoea. There might or might not be other associated hypothyroidism symptoms such as lethargy, sensitivity to cold, significant weight gain, slow movements and thoughts, constipation and muscle cramps. Treatment of hypothyroidism should restore menses, but this may take several months.

Other chronic conditions

There are other possibilities which are less likely and will require further evaluation before they can be picked up, including chronic kidney disease, diabetes and many other rarer conditions like prolactinoma, which is a noncancerous tumor of the pituitary gland. This can occasionally present as breast milk even when you have not even given birth! If there is persistent cessation of the menstrual cycles which lasts more than 3 months, do consider seeking professional help to detect any common problems or less common ones as well.

When to seek medical help for missed menses?

  • Cessation of menses is persistent - more than 3 months for regular cycles, more than 6 months for irregular cycles

  • Premature menopausal symptoms (less than 40 years old)

  • Excessive facial hair, acne, weight gain and infertility

  • Cold sensitivity, slow movement and thoughts, constipation and muscle cramps

  • Breast milk production even though you have not just given birth

You may choose to monitor your menstruation for a few cycles first, to see if it resolves on its own. However if you are in any doubt at all, do seek medical attention, whether for induction of menses, for investigations, or even just for reassurance.

If you have any specific questions related to Women’s Health, do drop by Paddington Medical Clinic to visit our lady doctor, Dr Zhang Huipei for a consultation. Also remember to protect yourself with regular pap smear screening and relevant cervical cancer vaccinations where appropriate.


Dr Zhang Huipei (Mdm)

MBBS (Singapore), GDFM (Singapore)

Family Physician

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