The easy answer is that the ring, like other birth control products, tricks the body into thinking that it is pregnant. This “trickery” occurs when the hormones in the ring (progestin and estrogen) are absorbed into the bloodstream from the walls of the vagina and keeps the ovaries from releasing eggs. The hormones also cause the cervical mucus to thicken, which keeps sperm from meeting with and fertilizing an egg. When the ring is removed, the body thinks that an egg was not fertilized and sheds the lining of the uterus. And so the cycle begins again with the reinsertion of a ring.