You've watched the tutorials. You've got the fold down. You've even tried three different brands. And it still leaks. If this is you, there's a good chance the problem isn't your technique at all. It's anatomy.

Specifically: your cervix.

Nobody talks about this enough, which is wild, because cervix height might be the single biggest factor in whether a menstrual cup works for your body. Let's fix that.

Your Cervix Isn't in the Same Spot as Everyone Else's

Here's the thing that doesn't get explained in the box insert: the cervix moves. It shifts position throughout your cycle, and it also sits at a different baseline height depending on the person, sometimes even depending on the day.

Some people have a high cervix, sitting further up the vaginal canal. Others have a low cervix, sitting closer to the opening. Neither is unusual, neither is a problem on its own. But it changes everything about how a cup needs to fit.

**High cervix:** a standard or short cup may not reach the cervix at all, so it never forms a proper seal against it — instead it just floats, and floating cups shift, tip, and leak.
**Low cervix:** a long cup can bump right into the cervix before it's fully open, which means an incomplete seal, plus that all-too-familiar pressure or discomfort that makes you want to rip it out five minutes in.

Once you know which category you're in, most of the "why does this keep leaking" mystery starts to make sense.

How to Actually Measure Your Cervix Height

This part sounds intimidating and it really isn't. It takes about thirty seconds, and you only need to do it once (though it's worth rechecking a couple times across your cycle since height does shift).

1. Wash your hands.
2. Insert one clean finger into the vaginal canal until you feel your cervix. It feels a bit like the tip of your nose, firm with a small dimple in the middle.
3. Note where your finger lands relative to your knuckles:
   - Cervix reachable at the first knuckle or less → low cervix
   - Cervix reachable at the second knuckle → medium cervix
   - Cervix requiring your full finger (or you can't quite reach it) → high cervix

Do this check during your period if you can, since that's closer to the position your cervix will actually be in when you're using the cup.

Matching Cup Design to Cervix Height

Once you know your number, cup shopping gets a lot less like guesswork.

Low cervix: look for shorter cups, or cups with a shorter stem you can trim down. Firmer cups can also be trickier here since they take more room to pop open. A softer cup that unfolds close to the cervix tends to seat more comfortably. A menstrual disc may also be your best fit.

High cervix: look for a longer cup, and don't be afraid of firmer silicone. A firmer cup holds its shape and seal even without cervix contact, which matters more when your cervix is out of reach. Poppins Period menstrual cups are made of firm silicone and are perfect for medium to high cervixes.

Medium cervix: you've got the most flexibility here. Most standard-length cups in soft or firm silicone should work, so fit comes down more to flow and personal comfort than cervix height specifically. Poppins period has three different sizes of menstrual cups- Teen, Small, and Large to accommodate most anatomies.

Adjusting Your Cup to Stop the Leaks

Even with the right cup, fit is still a skill, not a switch you flip. A few things worth trying:

Rotate after insertion. A quarter-turn helps the cup fully pop open and seals any folds that didn't release.
Do a seal check. Run a finger around the base;  it should feel rounded, not dented or folded in on itself.
Reposition, don't just remove. If you're getting leaks, try nudging the cup slightly higher or lower before assuming the cup itself is wrong.
Trim the stem. Especially for low-cervix folks, an untrimmed stem can be the difference between a comfortable seal and constant awareness that something's there.

The Bottom Line

Leaks usually aren't a sign you're "doing it wrong",  they're just a sign your cup and your anatomy haven't been properly introduced yet. Cervix height is one of the most overlooked pieces of that puzzle, and it's also one of the easiest to check for yourself in under a minute.

Once you know your height, choosing (and adjusting) the right cup stops being trial and error and starts being pretty straightforward. Leak-free periods aren't a myth. They just require the right fit for your body, not a generic one.

Curious what else about your anatomy affects your period care routine? That's a rabbit hole worth going down.