On average, a woman loses between 30-40 milliliters of menstrual blood during her period. However, menstrual blood loss can vary significantly between different women and different cycles.
What is a normal period blood loss?
During a normal period, it’s common for a woman to lose between 30-80ml of blood over the course of her menstrual cycle. This amounts to around 2-3 tablespoons. For the average 5 day period, this works out to:
- Day 1: 5-10ml
- Day 2: 20-30ml
- Day 3: 25-35ml
- Day 4: 20-30ml
- Day 5: 5-10ml
So in total, most women lose 30-40ml of blood during a normal period. However, anywhere from 10-80ml is still considered average.
Factors affecting menstrual blood loss
The amount of menstrual blood loss can vary significantly between different women. Here are some of the key factors that affect menstrual blood volume:
- Age – Blood loss is usually heavier in the first few years after menstruation begins (menarche). It typically lightens as a woman approaches menopause.
- Birth control – Hormonal contraceptives like the pill often decrease menstrual bleeding.
- Pregnancy – Some women have heavier periods after pregnancy.
- Medications – Blood thinners and NSAID pain relievers can sometimes increase bleeding.
- Medical conditions – Conditions like endometriosis, uterine fibroids and cancer can cause heavy periods.
- Genetics – Some women inherit a tendency for heavier bleeding.
Heavy Menstrual Bleeding (HMB)
If a woman loses more than 80ml of blood during her period, this is considered heavy menstrual bleeding (HMB), or menorrhagia. Around 1 in 5 women suffer from HMB.
With heavy bleeding, it’s common to pass large blood clots and change pads or tampons frequently. This can cause a range of physical symptoms like fatigue, dizziness and shortness of breath. It can also impact daily life and lead to issues like anemia if left untreated.
Causes of Heavy Bleeding
Some of the main causes of abnormally heavy periods include:
- Uterine fibroids – non-cancerous growths in the uterus
- Endometriosis – uterine tissue growing outside the uterus
- Adenomyosis – uterine tissue growing into the uterine wall
- Hormone imbalances
- Intrauterine devices (IUDs) like the copper IUD
- Cancer of the uterus, cervix or ovary
- Inherited bleeding disorders like von Willebrand disease
Treatment for Heavy Periods
Heavy menstrual bleeding can be treated with medications like:
- Hormonal birth control like the pill, patch or ring
- Tranexamic acid tablets
- NSAIDs like ibuprofen to reduce bleeding
- Oral or injected progesterone therapy
If medication doesn’t help, surgical procedures may be recommended, like:
- Endometrial ablation – destroys the uterine lining
- Uterine artery embolization – blocks blood flow to fibroids
- Myomectomy – removes fibroids
- Hysterectomy – removes the uterus
When to see a doctor
See your doctor if you experience any of the following:
- Bleeding that soaks through 1 pad or tampon an hour for multiple hours
- Passing blood clots larger than a quarter
- Periods lasting longer than 7 days
- Symptoms like fatigue, chest pain, shortness of breath
- Bleeding between periods
Sudden heavy bleeding can be a sign of issues like fibroids, endometriosis or hormonal imbalance. It’s important to seek medical advice to determine the cause and best treatment options.
Measuring menstrual blood loss
For women with heavy periods, measuring menstrual blood loss can help determine whether excess bleeding is occurring. Here are some of the main ways blood loss can be measured:
Total Blood Loss
This involves collecting all menstrual blood, including on pads, tampons and in the toilet. The total volume can then be measured. This gives the most accurate picture of blood loss over a whole period.
Alkaline Hematin Method
Used in clinical studies, this test extracts and measures heme from used pads and tampons. It helps calculate the total blood loss in milliliters.
Pictorial Blood Loss Assessment Chart (PBAC)
This chart allows women to assign a score to menstrual products like pads and tampons based on coverage of blood. Totaling the scores over a period gives an estimate of blood loss.
Ferritin Blood Test
Ferritin is a protein that stores iron. Low ferritin levels indicate your body’s iron stores are depleted and suggest a possibility of iron deficiency anemia secondary to heavy periods.
Hemoglobin Blood Test
Hemoglobin carries oxygen through your blood. Low hemoglobin indicates anemia – a possible symptom of heavy menstrual bleeding.
How do different sanitary products absorb and collect blood?
Here’s an overview of how much blood different feminine hygiene products can absorb:
Tampons
- Regular: 5-9ml
- Super: 10-12ml
- Super plus: 15-18ml
Pads
- Regular: 10-15ml
- Super: 15-30ml
- Overnight/Extra heavy flow: 40-60ml
Menstrual Cups
- Small size: 20-30ml
- Large size: 30-40ml
Tampons and pads absorb the blood, while menstrual cups collect it. Changing tampons every 4-8 hours and pads every 2-4 hours is recommended based on flow.
Impact of heavy periods
Heavy menstrual bleeding can cause a range of problems including:
Physical effects
- Fatigue and weakness from iron deficiency anemia
- Headaches
- Dizziness, palpitations
- Shortness of breath
Emotional effects
- Depression
- Mood changes
- Embarrassment
- Low self-esteem
Social effects
- Interference with work, school, exercise
- Inability to participate in activities
- Isolation
Other impacts
- Disrupted sleep
- Soiled clothing and bedding
- Relationship issues
- Low iron levels
Seeking medical treatment can minimize the effects of heavy periods on quality of life.
When does a girl start her period?
The average age for a girl to get her first period (menarche) is around 12, but it can happen anytime between 8-15 years old. The timing of menarche is influenced by factors like:
- Genetics
- Body weight – girls who are overweight may start earlier
- Diet and nutrition
- Physical activity – high levels of exercise can delay menarche
- Chronic disease
- Environmental factors
Around the time of her first period, a girl will begin developing signs of puberty like breast growth, pubic hair and body odor. Periods can be very light and irregular for the first 1-2 years before settling into a more regular cycle.
When does menopause start and end?
On average, women go through menopause between the ages of 45 and 55. Menopause is defined as reaching 12 months without a period. The transition to menopause is known as perimenopause and can last 4-8 years before the final period.
Some key milestones in the menopause transition include:
- Early perimenopause – irregular periods start.
- Late perimenopause – skipping periods for months.
- Menopause – final period.
- Postmenopause – after 12 months without a period.
Symptoms like hot flashes, night sweats, vaginal dryness and mood changes often accompany the menopause transition as hormone levels change.
Stages of the menstrual cycle
The menstrual cycle is divided into different phases based on ovarian hormone levels. The cycle length averages 28 days, but can range from 21 to 35 days. The main stages include:
Follicular phase (days 1-14)
- Day 1: Period starts
- Ovary prepares an egg for release
- Uterine lining starts thickening
- Estrogen rises, triggers ovulation around day 14
Ovulation (day 14)
- Ovary releases a mature egg
- Estrogen peaks
Luteal phase (days 15-28)
- Corpus luteum produces progesterone
- Uterine lining continues to thicken
- If no pregnancy, progesterone drops
- Uterine lining sheds through period around day 28
These cycle phases are controlled by the complex interactions of hormones like estrogen, progesterone, FSH and LH.
Conclusion
Menstrual blood loss is highly variable between different women and cycles. On average, women lose 30-40ml of blood over the course of a normal period. Heavy menstrual bleeding is defined as losing over 80ml per cycle. A number of factors from age to medications can affect menstrual flow.
For women with heavy periods, measuring blood loss and tracking symptoms is important. Excessive menstrual bleeding can cause issues like anemia and often responds well to treatment with medications, medical devices or surgery when needed.