When estrogen levels remain low, less moisture comes through the vaginal wall to provide lubrication during intercourse. The elastic and collagen fibers that give the opening strength and stretchiness decrease in number, and the skin of the opening becomes thinner and less protective. Sometimes, the opening shrinks and becomes quite narrow. The thinning of the skin can make penetration more uncomfortable than pleasurable for some women, and when the vaginal opening narrows, intercourse can be very painful. When a woman stops having vaginal intercourse due to pain, the changes may worsen even faster. In rare, extreme cases, thinning of the tissue may lead to tiny abrasions that cause the sides of the vaginal opening to stick together and the opening may become fused closed in places.