I'm not sure exactly what a "light flow" or a "heavy flow" is. I think my first period was light, and it lasted 4 days. Should my flow fluctuate?

Light flow and heavy flow are kind of what they sound like. A light flow is when you’re not bleeding a lot. A heavier flow is the opposite. It’s more blood and you may be soaking through your tampon or pad more often. My flow is a lot lighter toward the end of my period and a panty liner is all I need, and at the beginning of my period, a heavier absorbency tampon is necessary. You’ll start to see a pattern as you continue to get more periods. Hope that helps!

“Light flow” is what I consider the easier part of having your period. There’s not much fluid that you catch with your pad or tampon and it’s a very small amount. “Heavy flow” is when there is much more blood to catch and you change pads and tampons more frequently. You’re also correct in wondering if your flow will fluctuate. That’s very true and you can expect it to change as you age or if you take certain medications (like birth control pills).

Light flow and heavy flow can be subjective descriptions -- meaning light and heavy flow to you don’t always mean light and heavy flow to your best friend. Generally, menstrual flow is considered too heavy when you need to change your pad or tampon every hour for a few hours in a row. Bleeding like this is a reason to head to see your healthcare provider right away. Light flow (in my opinion) is when you really don’t have to change your pad or tampon every four hours, but you should to keep yourself clean and to prevent odors and infections. Your first periods may be light because your body is getting used to building up that uterine lining and regulating all of the hormones that play a role in making your period happen. Once it is regular, most periods last between three and seven days with a day or two of heavier flow (where you need to change your pad every four hours or so), then tapering off toward the end.