It doesn't "pop" or anything like that and has very little to do with gravity. The ONE time I've neglected my cup, it leaked a bit - I felt it and remedied it right away. It doesn't back up. . .I'd imagine if you didn't remove it and empty it it would eventually break it's seal and slide out, but we're talking HOURS past normal wear/change schedule.

Additionally, I have a tilted uterus as well. The first cup I tried was too large and did not work effectively. It wouldn't "seal" at all. I ordered a smaller size, and viola! Perfect. The Luna comes in the smaller size.

As far Instead goes, I checked out the other sites as well. I'm not certain why these women had such issues, but I suppose anything is possible. I work and live near a large research hospital and they conducted a study here for Instead (which I missed out on!) with 2500 women. I can't find the link (will keep looking though) but I recall that a large percentage of women were happy with the cup and the alternative to traditional menstrual methods.

My gyn gave me information about the cups and the lowered risk for TSS. I found this particularly convincing for me as I've already had one bout with it during my teens.

I'm curious. . .what's the big deal about touching your own body? Is it just a lack of understanding about how your body works or would it be related to abuse issues?