As a fellow NuvaRing user and a pharmacist, I have to point out that your information is incorrect. The NuvaRing IS a different delivery system for the hormones, but they produce systemic effects just like every other type of HBC out there - not just local effects.

Straight from the NuvaRing website: "NuvaRing® contains 2 types of hormones: estrogen and progestin, which work together to prevent your ovaries from producing mature eggs. These are the same hormones found in the Pill, and they work the same way in your body even though they are administered differently with NuvaRing®."