For nulliparous women (i.e., those who have never given birth) and who ever used OCs and nulliparous women who used OCs for at least 4 years, corresponding ORs were 1.24 and 1.29.

• 曾使用过口服避孕药和使用口服避孕药四年以上的未产妇（未生育的妇女）其相关性分别为1.；24和1