How fast does primrose oil work to ripen cervix for labor?

Evening primrose oil is believed to help soften and ripen the cervix, potentially preparing it for labor. However, the timeline for its effectiveness can vary widely among individuals; some may notice changes within a few days, while others may take longer. It's important to consult with a healthcare provider before using it, as research on its efficacy and safety is limited. Ultimately, its impact on labor initiation can differ based on various factors, including individual health and pregnancy conditions.