Up to 70% of perimenopausal women develop bladder problems — the urgency, the leaks, the 3am trips, the UTIs that keep coming back when they never used to. It is one of the most common and least discussed symptoms of the hormonal transition. The mechanism is specific: estrogen has receptors throughout the entire urogenital system, including inside the bladder's own bacterial ecosystem — the urobiome. When estrogen drops, four systems fail simultaneously. Here's the science.