What Causes a Light Period?

Periods can be a key indicator of general health. Most people who menstruate often find that their period flows vary from month to month and year to year. They may experience some sort of irregularity every so often and some months may be lighter than others. Occasionally, a very light period can be a sign that something is off with your health, be that issues with stress, hormone levels, weight loss or another medical condition.

What is your period trying to tell you? When is it time to worry? What’s not normal? We asked our WUKA Period Health Expert Dr. Nitu Bajekal to share insight into why some periods might be unusually light and when this might be cause for concern.

What Does a Light Period Look Like?

A light period, also called ‘hypomenorrhoea’, can refer to both the length of bleeding and lighter flow. It’s difficult to accurately figure out how much menstrual fluid leaves your body during your period. Typically, you can estimate the amount of menstrual fluid lost based on how saturated your period products become.

On average, you will lose about 30 to 72ml of blood during your period, although some people bleed more heavily than this. In less medical terms, this is about 5 to 12 teaspoons. A light period is usually defined as losing less than 30 to 35ml of blood during your period. Again, in less medical terms, 10ml of period flow equates to around 2 small tampons' worth. ‘Light periods as a rule are not a concern if periods come at regular intervals (24-35 days)’, said Dr. Nitu.

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What's Considered Normal Flow?

It’s important to know what is ‘normal’ for you, from how long your period lasts, how light or heavy it tends to be and how long your bleeding lasts. Understanding what a ‘normal’ period looks like for you will help determine if your period is in fact light. Some people have consistently light flows and others may experience heavy bleeding month-on-month. Tracking your menstrual cycle using a period tracker app – or a diary – is a useful way of gauging what is normal for you and to spot any changes each month.

Spotting vs Light Flow

A common question Dr. Nitu gets asked is how spotting differs from very light periods: ‘Spotting can come from your uterus, cervix or your vagina, whereas your period comes from monthly shedding of your uterine lining, or endometrium’, she shared. Spotting refers to any light bleeding that does not occur during menstruation in your menstrual cycle. In terms of the amount of blood, spotting could be measured as a spot of blood on toilet paper. Put simply, it is usually light vaginal bleeding outside or between your periods that doesn’t require a menstrual product (though you may opt to use one for protection).

Generally, if you experience light bleeding at least 2 days before or after your period, you can consider this as part of your period. And, remember, spotting can be a common side effect of hormonal contraception, an occurrence during ovulation or a symptom of early pregnancy. Any unexplained spotting should be discussed with your healthcare provider, especially if it is persistent or after sexual intercourse. ‘Remember to be up-to-date with your cervical screening if you are eligible’, said Dr. Nitu.

Causes of a Lighter Period

There are various factors that contribute to your monthly flow and any changes in heaviness you may experience. Dr. Nitu said that ‘light periods may be seen at extremes of age, during nursing and while on hormonal contraception’.

So, let’s explore what can cause a lighter period.

Stress

Be it physical or emotional, being stressed can affect your menstrual cycle. Stress can cause your brain to inhibit the production of reproductive hormones that are necessary for a normal period. In medical speak, stress increases levels of stress hormones (glucocorticoids, like cortisol) that inhibit the body's main sex hormone, gonadotropin releasing hormone (GnRH). 

When these hormones are blocked, your ovulation can be suppressed or delayed and you may experience light periods. Stress can also cause spotting or worsened PMS symptoms. Typically, once the stressors pass, your ‘normal’ periods should resume.

Birth Control 

Hormonal birth control methods are known to reduce period blood loss in those with no underlying health issues. Some methods prevent an egg from being released into the body and fertilised, so the uterus lining doesn’t thicken and you can experience light periods. Such hormonal birth control methods include the combined contraceptive pill, the patch, the vaginal ring, the shot and the hormonal IUD.

Breastfeeding

If you are breastfeeding, the milk production hormone (prolactin) prevents ovulation – and therefore your periods – from occurring. This is also known as ‘lactational amenorrhea’. When you start reducing the amount of time you spend breastfeeding your baby, you may have very light periods at first. Most breastfeeding mothers see their periods return between 9 and 18 months after their baby’s birth.

In our blog post about periods after pregnancy, another WUKA Period Health Expert Dr. Brooke Vandermolen said: ‘It’s normal if your periods don’t come while you're breastfeeding. It’s also normal if they return. It can be 4 or 5 weeks after birth, but it can be not for 18 months. It’s very variable.’

Diet

It’s common knowledge that the food and drink we consume affects our health. This includes menstrual health. Food can affect your hormones which in turn determines your mood, how long you bleed and even how much you bleed.

Dr. Nitu, aka the ‘Plant-Based Gynae’, is regularly asked whether or not veganism and vegetarianism affects your periods. ‘While studies around the effects of vegan and vegetarian diets on your periods are inconclusive’, she said, ‘it has been found that people who eat plant-based diets often report slightly shorter and less heavy periods than the average, which is a good thing. There is no reason to have low iron levels on a varied and diverse plant predominant diet, rich in leafy greens such as kale, beans, lentils, tofu, apricots, herbs, spices and nuts. If one is having heavy periods, whatever one’s diet, this should be investigated by your doctor.’

Eating a balanced and healthy diet and drinking lots of water is crucial to maintaining a regular menstrual cycle, and can reduce painful period symptoms too. If you have been trying out a new diet, or eating too much or too little, you could notice irregular or light periods. Alternatively, heavy periods can often be managed by eating the right foods but only after a thorough check with your doctor and ensuring you are not anaemic. The right diet can also help even when you need medical treatment.

Medication

As well as hormonal birth control methods, many different medications can affect your menstrual cycle. Dr. Nitu explained how medications can affect cycle regularity and period flow: ‘Painkillers known as nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and naproxen, can make the flow lighter during your period.’

With regards to herbal remedies, Dr Nitu said that ‘regular intake of ginger and also during the period can help some with nausea, pain and flow associated with the release of chemicals called prostaglandins, similar to how NSAIDs work.’

Hormonal Issues

Our bodies contain over 50 different types of hormones. Hormones control a number of bodily functions, including sexual health, reproduction, growth, mood and metabolism. An imbalance in hormonal levels is one of the main causes of light periods. For example, if you have too much thyroid hormone or too little, your period will be affected. Your period could become very light, stop for months or become very heavy.

WUKA’s complete guide to period blood colour shares what different blood colours may indicate. The colour of your period blood can give you valuable insight into what is happening with your hormones and overall health. Health conditions such as perimenopause and PCOS (read more below) can change the colour and flow of blood.

Weight

Fluctuating weight can change your periods, making them lighter or shorter. People who are underweight or who quickly lose a large amount of weight may notice that their periods are very light or that they stop altogether. This happens because their body fat level becomes too low, which can put your body in stress mode, imbalance the body’s hormone levels and possibly stop ovulation. ‘This is another reason why eating a balanced and healthy diet is crucial to having a balanced and healthy menstrual cycle’, said Dr. Nitu.

Pregnancy

If you are pregnant, you will not experience a period. Implantation bleeding, which looks similar to spotting described earlier, is when the fertilised egg attaches itself to the lining of the uterus. This happens around 10-14 days after conception. Implantation bleeding often happens earlier than when a normal period is due, so it is often mistaken for an early period.

Light vaginal bleeding (outside of the times of implantation bleeding) during early pregnancy can be a common thing to see, usually within the first 20 weeks. This can also be sometimes confused with a light period when in actual fact it is spotting. This particular bleeding in early pregnancy could be related to changes in hormones, specifically the production of progesterone swapping from the ovaries to the placenta being formed. If you are pregnant and experience heavy bleeding, please contact your healthcare provider.

Your first postpartum period after giving birth may differ to what your periods were like before birth. Though they may have been regular before, they could be irregular afterwards. Some people find that their first period after birth is really light. It may then go away, they have nothing else for a while, and then they get another period and it’s heavy. You can read more about periods after pregnancy here.

Over-exercising

Staying active and exercising during your period can help to reduce symptoms like bloating, fatigue, menstrual cramps and headache. Excessive exercising, however, can cause changes in the hormones responsible for your periods. This can result in altered periods, including very light periods, skipped periods or no period at all (also called ‘amenorrhea’).

As you have read, one's menstrual flow is dependent on a number of factors. While one person may experience lighter periods with cardio exercise, someone else may not, Dr. Nitu explained. ‘It is recommended to keep track of your menstrual cycle along with your exercise routine to help identify what type of movements work best for you and your body.’

Menopause

The first sign of approaching menopause is a change in the ‘normal’ pattern of your periods. Fluctuating hormone levels during the lead-up to the menopause (or perimenopause) causes the body to ovulate less. In general, people in perimenopause tend to experience lighter or irregular periods. This can be because oestrogen levels are low and, therefore, the uterus lining hasn’t thickened. It’s important to note that these changes vary between people.

PCOS

According to the NHS, 1 in 10 women have been diagnosed with Polycystic Ovarian Syndrome (PCOS). PCOS is the most common female hormone disorder. Some people with PCOS will experience very light periods, irregular periods or no periods altogether, plus other symptoms like weight gain, fertility problems and increased facial hair. Having PCOS increases your risk of developing other health problems later in life.

‘If you have any of the symptoms discussed above, go and see your GP who should order some blood tests and an ultrasound scan to assess the ovaries’, says Dr. Nitu, author of Living PCOS Free. PCOS is a condition that should be addressed with your healthcare provider, which leads us on to our concluding section.

When to See Your Doctor

As we have shared, light periods can happen for various common reasons, many of which will not require a trip to your healthcare provider. If you experience a significant change in your period flow, it’s important that you seek medical investigation.

Our WUKA Period Health Experts recommend tracking your periods for 3 months before seeing a doctor, giving you enough time to spot any patterns or changes. However, you must seek medical advice if you are concerned at any time and not wait.

KEY TAKEAWAYS:

About Dr. Nitu Bajekal MD FRCOG Dip IBLM:

Dr Nitu Bajekal is a Consultant Gynaecologist and Women’s Health Specialist with over 35 years’ experience, providing medical and holistic care for women with a variety of health concerns. She has special expertise in several areas, including the management of heavy and painful periods, menopause, fibroids, polycystic ovarian syndrome (PCOS) and cervical cancer screening (colposcopy and LLETZ). Dr Bajekal is also a Board-Certified Lifestyle Medicine Physician and author of Living PCOS Free.

Find out more about our WUKA Period Health Experts here.