https://fujito.clinic/column/index.php/2022/08/25/1916/#:~:text=%E7%94%9F%E7%90%86%E4%B8%AD%E3%81%AE%E8%87%AD%E3%81%84%E3%81%AF,%E3%82%82%E3%80%81%E9%9B%91%E8%8F%8C%E3%81%AE%E5%A2%97%E6%AE%96%E3%81%A7%E3%81%99%E3%80%82
https://www.sofy.jp/ja/advice/period-changes/34.html