How much blood should I lose in a period?

How much blood is too much blood to lose in my period?

Our period, yep that key feature of our menstrual cycle and probably the one that requires a lot of logistics. No doubt that once you start tracking your menstrual cycle, that small bit of worry (the ‘when will it come’) eases. That is the beauty of menstrual cycle tracking, it allows us to at least be prepared at the right time and have our period products close by for when the inevitable period does arrive.

But aside from knowing when we will get our period, how do we know if it is too heavy? Or what is considered prolonged menstrual bleeding?

The length of the bleed phase

Let’s start with how long menstrual bleeding usually lasts.

Generally, we see that a menstrual bleed can last anywhere from 3-6 days. Typically we see in the research that women with shorter cycles will have shorter periods, while women with longer cycles will have longer periods. 

Fun fact, as we we get older, we also see the average period length increase by about 1 day. What this means is that younger women, 15-24 years old, will have an average menstrual bleeding length of 3-3.5 days, while women who are 30-50 years old generally have an average menstrual bleeding that is ~4-4.5 days long. Prolonged menstrual bleeding is when a period lasts more than 7 days. If you are someone who has experienced periods that consistently last longer than a week, then I would really encourage you to see if you can get some support from your healthcare professional.

Now onto period volumes. 

Ok, interesting story for you, some of the initial research in this area was completed in the 1960/1970s. To measure menstrual fluid loss in these original studies, they got women to put their used pads and tampons in plastic bags and leave them at the lab. The researchers then extracted the fluid from the products and this is where the original research definition for heavy menstrual bleeding came from. 

In research, it has been considered that menstrual fluid loss of more than 80 ml (about ⅓ Cup) is a heavy period. This definition has mainly been used in a research setting as there has been no practical or clinical method for women to determine actual period volumes from pads and tampons. With the arrival of cups, there is a bit more of an opportunity for women to understand their period volumes. But in saying that, more recent research used cups to measure period volumes and here they found that the average volume lost by healthy women was 80mls. In this study, they found that the range of menstrual fluid that was lost by healthy women was anywhere between 15-271 mls. Which then really does raise the question, what is too much when it comes to our period?

Factors influencing volume of blood lost 

In reality, the total volume lost each period is probably very individualistic and will be influenced by so many factors like age, hormones, stress, number of pregnancies, stature and much much more. The more commonly accepted clinical definition for heavy menstrual bleeding is menstrual fluid loss that interferes with a woman’s physical, social, emotional, and material quality of life.

This definition of heavy or abnormal menstrual bleeding allows us to take into account our own unique experience of our period. If you or someone you know does have a really hard time when your period starts and if it negatively affects your life, then please, make sure you get some support for this.