Your period is a healthy part of the menstrual cycle. It is the shedding of the endometrium (the lining of the uterus) that grows each cycle to support a potential pregnancy. The first day of your period is the first day of your menstrual cycle.
Your period can be an important indicator of your health. It’s important to know what’s “normal” or typical for you. That means how often your period happens, how light or heavy it is, and how long it lasts.
Changes to your period
Periods fluctuate for a while after they first start (menarche), after pregnancy, and as they come to an end (perimenopause). Not ovulating regularly — anovulation — is common during these times, and is a common cause of temporarily absent or heavy menstrual periods . If you don’t ovulate each cycle — you may miss a period, or it may come later than usual, and/or be heavier or lighter and/or shorter or longer than your usual period .
In between these life stages, your period should generally be about the same length and volume each cycle. You may still notice some changes though — the heaviness and length of your period depends on your hormones, which can fluctuate. Hormones can change temporarily because of things like stress, exercise, diet, or taking an emergency contraception pill (the morning after pill) (3-6). Every period is different, just as every body is different.
Periods and uterine bleeding can also fluctuate because of certain health conditions, like uterine polyps, fibroids, or PCOS — conditions that should be addressed with your healthcare provider. Certain bleeding conditions, medications, and infections can also affect menstrual bleeding, and cause irregular spotting.
If you use hormonal contraception, your period/bleeding patterns may be different.
Estimating the volume of your period
It is difficult to figure out how much menstrual fluid leaves your body every cycle. If you use a menstrual cup, these often have volume measurements (ex. 10 mL, 15 mL, 25 mL) indicated on the side of the menstrual cup to help you estimate how much fluid you have lost.
In general, the amount of fluid lost can be estimated when using pads or tampons, depending on the size and soaking amount of the menstrual product. A fully saturated light tampon can hold up to 3 mL of fluid, while a fully saturated super tampon may hold up to 12 mL. A regular daytime fully soaked pad may hold around 5 ml of fluid, and fully soaked overnight pad may hold 10-15 mL.
If you are repeatedly soaking through a tampon or pad every two hours, this is considered heavy menstrual bleeding and should be brought to your healthcare provider’s attention.
Making Sense of Menstrual Flow
How are you supposed to know if your menstrual cycle is light, medium or heavy? After all, women don’t usually compare this information and what seems heavy to one woman may be positively light to the next.
The large-scale TREMIN research project, which has been tracking thousands of women’s menstrual cycles for more than 70 years, has the Mansfield-Voda-Jorgensen Menstrual Bleeding Scale (named for the researchers who developed and tested it). The six-point scale helps women accurately understand their periods and alert them to an underlying problem:
Spotting: A drop or two of blood, not even requiring sanitary protection, though you may prefer to use some.
Very Light Bleeding: Needing to change a low-absorbency tampon or pad one or two times per day, though you may prefer to change them more frequently.
Light Bleeding: Needing to change a low- or regular-absorbency tampon or pad two or three times per day, though you may prefer to change more frequently.
Moderate Bleeding: Needing to change a regular-absorbency tampon or pad every three to four hours, though you may prefer to change more frequently.
Heavy Bleeding: Needing to change a high-absorbency tampon or pad every three to four hours, though you may prefer to change more frequently.
Very Heavy Bleeding or Gushing: Protection hardly works at all; you would need to change the highest absorbency tampon or pad every hour or two.