Distribution of the follicular and luteal phase lengths and their age‐dependent changes in Japanese women: A large population study oleh Sawa Mitake, Osamu Wada‐Hiraike, Kosuke Kashiwabara, Akari Nakamura, Risa Nasu, Maaya Hine, Yutaka Matsuyama, Tomoyuki Fujii, Yutaka Osuga