Castor oil has been associated with inducing labor for years, but it only might work. Castor oil stimulates the gastrointestinal system, acting as a laxative. Your GI system and uterus are geographically close to one another within your body, so the theory is that if you stimulate your bowels, you can stimulate your uterus.
I’m fully supportive of non-pharmaceutical options if they’re evidence-based, but unfortunately the safety of castor oil inductions remains unclear. As a midwife, I’ve witnessed that drinking castor oil to induce labor can lead to diarrhea and dehydration without ever starting labor. And worse yet, it may cause a “dysfunctional” or suboptimal labor pattern, which may lead to unnecessary intervention.