How Much Blood Does A Woman Lose On Her Period?

Overview

During the menstrual cycle, women bleed 3 to 8 days out of a month, which is called their period. Menstrual blood, which is released from the cervix and subsequently expelled through the vagina, is your body's way of removing the lining of the uterus throughout this process.¹

Throughout the month your body prepares itself for the potential fertilization and implantation of an egg, which will result in pregnancy. In the absence of pregnancy, progesterone and estrogen levels fall, which causes your body to begin menstruating.²

How much blood do you lose on your period?

The average woman loses 30 to 72 ml (5 to 12 teaspoons) of blood during her period. Periods are usually heaviest on the 2nd day of menstruation. Period blood will usually be bright red at its heaviest and it may be pink, or brown on lighter days.¹ 

How can you measure how much blood you are losing? 

Menstrual blood is quite challenging to quantify, but there are a few ways to determine how much blood is lost throughout your period. 

One way of measuring blood flow is through menstrual cups. Menstrual cups are placed into the vagina to collect period blood. It can hold up to 10 to 38 ml of blood and should be replaced every 4 to 12 hours. This is an effective way of measuring how much blood you are losing. You can look at how much of the cup is filled and take a note when changing it to calculate your overall blood loss.³ 

An alternative way of measuring menstrual flow is through measuring menstrual pads and tampons. You can measure a pad or a tampon before and after use and weigh it and calculate how many sanitary products were used and the duration of the menstruation to measure blood loss.⁵ 

Another method that could be used is by comparing images of used period pads and by keeping a record number of pads used and the degree it was soaked according to the images and the size of blood clots.⁶ 

Chemical tests using alkaline hematin can also be done to measure blood loss on pads and tampons during periods.⁴ 

However, it is extremely difficult to quantify blood flow during menstruation since menstrual flow only contains 30 to 50% of blood compared with the total volume. The extra fluid in period blood is tissue fragments and debris from the breakdown of superficial endometrium all of which make it extremely difficult to calculate how much blood is lost.⁷ 

Light menstruation 

Most menstrual flows consist of about 5 to 12 teaspoons of blood. If you feel that your period may be light, there may or may not be a reason for that period as it is difficult to determine how much blood you are losing and can vary from month to month most of which are not cause for concern.⁸ 

Causes of light menstruation

Lighter periods can be caused due to: 

1. Pregnancy: During pregnancy, your period will stop since your body is no longer releasing eggs for fertilization. Around the time your period would be due you may experience light bleeding, often called spots, which is when the developing embryo plants itself in the womb. This is a common occurrence and does not mean something is wrong with the pregnancy⁹
2. Breastfeed: Your period may not return to normal until you stop breastfeeding. For some women, their periods may return a few months after birth⁹
3. Birth Control: Using birth control can cause you to miss your period and some types of birth control can stop your period completely. This is not a cause for concern, once you stop using contraceptive pills your normal menstrual cycle should return.⁹
4. Eating Disorders: Anorexia can stop your period. Losing an excessive amount of body fat can stop ovulation. It is also very unhealthy and can bring about irregularities to your period or can stop it altogether⁹
5. Weight Gain: Gaining an excessive amount of weight can cause you to miss your period. If you are overweight, losing weight can restart your menstrual flow and similarly gaining weight will restart your period if you are underweight⁹
6. Stress: can cause your periods to become longer or shorter, they might become more painful or stop completely. However, managing stress and taking time to relax can help you return to your normal cycle⁹
7. Hormonal Causes: Hormonal changes or problems with reproductive organs such as conditions like Polycystic ovary syndrome (PCOS) can affect menstrual flow⁹ 

Complications caused by light periods could be¹⁰

• Issues with pregnancy and infertility. It is not possible to become pregnant if you do not ovulate and if you do not have menstrual periods
• Stress
• Cardiovascular disease and Osteoporosis. Having insufficient estrogen can result in these two problems
• Pelvic pain 

When to see a doctor

You should visit a doctor if you are not pregnant and have missed 3 periods in a row. Your doctor may advise you to wait until your period returns and, in some cases, treatment may be given.⁹ 

You should see your doctor if your periods have stopped before you’re 45 and if you are over 55 and still have bleeding.⁹ 

Heavy menstruation

Heavy Menstruation is heavy if there is blood loss of 80mL or more during a menstrual cycle. It is very common in women and can affect a woman's well-being emotionally and physically and reduce her quality of life.¹¹ 

Heavy menstruation can be caused by

• Adenomyosis
• Fibroids and polyps
• If you don't ovulate regularly, the endometrium, which lines the uterus, can get too thick in some places. This syndrome is typical during puberty and perimenopause. Women who have specific medical disorders, including polycystic ovarian syndrome (PCOS) and hypothyroidism may also experience it
• Medications: Heavy menstrual bleeding can be caused by aspirin and blood thinners. The first year of usage of the copper intrauterine device (IUD) can lead to greater menstrual flow
• Cancer: Heavy periods can be a sign of endometrial cancer in its early stages. Endometrial cancer is most commonly diagnosed in women in their mid-60s who have passed menopause. It is often found at an early stage when treatment is most effective
• Other causes: Heavy menstrual bleeding can be brought on by endometriosis. Pregnancy-related factors like miscarriages and ectopic pregnancy are among the other causes

Assessment for heavy menstrual blood includes a woman's menstrual and gynecological history and a bleeding score to figure out which women need more blood tests. A pelvic exam and ultrasound scan help rule out the possibility of any underlying disease.¹¹ 

Complications of heavy bleeding 

Untreated heavy blood loss can bring about anaemia which is a common blood problem that can make you feel tired and short of breath. A severe case of anaemia can make it difficult to breathe and raises the chance of developing cardiac problems.²⁰ 

When to see a doctor

Signs of heavy menstruation are:¹²

• Having a period that lasts for many hours and drenched through one or more tampons or pads every hour
• To manage your menstrual flow, you use two pads together
• Replacing tampons or pads in the middle of the night
• Menstruation is longer than 7 days
• Have a period that contains blood clots that are at least the size of a quarter  
• Have a period that prevents you from carrying out your typical activities
• Enduring ongoing lower stomachache when you are menstruating
• Having no energy, feeling tired and out of breath 

Heavy menstruation does not always have to be treated but there are some treatments available that can help with the condition

When treatment is given, medication is usually given first¹³ 

• Hormonal birth control is given to treat problems with ovulation, PCOS endometriosis, and fibroids; this can help lighten menstrual flow and help periods become more regular¹³ 
• Hormone therapy can be given for heavy menstrual bleeding during perimenopause¹³
• Gonadotropin-releasing hormone (GnRH) agonists slow the growth of fibroids and stop the menstrual cycle¹³
• Ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs) can help stop heavy bleeding and relieve cramps during your period. Your doctor may prescribe medications to help with blood clots¹³

Your doctor will typically recommend you for tests or to consult a specialist if these therapies do not relieve your heavy periods or if they believe a medical condition is a cause.¹⁹ 

If medication does not help with the treatment surgery might be recommended 

• The uterine lining is removed during endometrial ablation. Menstrual bleeding is reduced or stopped Although it is unlikely, pregnancy can occur following ablation¹³ 
• Fibroids can be treated with uterine artery embolization (UAE). The uterus' blood vessels are stopped in the uterine artery embolization, which prevents the blood flow that causes fibroids to grow¹³  
• Myomectomy is a type of surgery that takes out fibroids without taking out the uterus¹³ 
• In some cases, hysteroscopy can be used to get rid of fibroids or stop bleeding caused by fibroids¹³ 
• A hysterectomy is carried out to be surgically removed. When alternative forms of treatment have failed or are not an option, hysterectomy is done to treat fibroids and adenomyosis. Endometrial cancer is also treated with it. After the uterus is taken out, a woman will no longer have periods and won't be able to get pregnant¹³ 

Irregular menstruation 

Menstrual flow is thought to be irregular if your menstrual cycle is inconsistent and keeps changing, making your periods start late or start early.¹⁴ 

Causes

There are many causes of irregular menstruation such as:¹⁴

• Complications with pregnancy
• Weight gain or loss
• First few years of puberty
• When starting menopause (between ages 45 to 55)
• Stress
• Over-exercising 
• Medical conditions such as thyroid condition or PCOS

How to manage irregular periods

Track it 

Tracking your period can help you learn more about your body and mental state, prepare for your period, predict when you will ovulate, and/or tell your doctor about your menstrual cycle.¹⁵ 

Water

Drinking water may help in reducing the duration and pain intensity during the menstrual cycle.¹⁶ 

Consuming iron 

Excessive blood loss can cause iron deficiency and can eventually lead to anaemia. Changing what you eat to get more iron in or using iron supplements is effective for treating anaemia.¹⁷ 

Light exercise

Working out may reduce pain intensity and reduce the amount of blood you lose during your period.¹⁸ 

Summary 

Your period will vary from month to month, which is typical. It could be light one month and heavy the next, but it is best to see a doctor if you think something is wrong. If you have periods that last for longer than 7 days or you are losing excessive amounts of blood which could cause anaemia, it is best to go to your doctor so you can get a diagnosis and work out a treatment plan.

Some of the painful symptoms of heavy or irregular menstruation can be reduced by making lifestyle changes such as drinking more water, getting more exercise, and eating more iron.