Cause and effect

Walking
If a woman is in early labor, walking can help contractions to continue and to be more effective.  Walking in early labor can also decrease the amount of pain she experiences. However, if a mom-to-be is not in labor, walking will not provoke labor and, in fact, will only exhaust her.
Taking castor oil
Castor oil is a laxative the stimulates the bowels to move faster, which can also stimulate uterine contractions. If a woman’s body is ready to go into labor, the castor oil may cause the process to begin. However, castor oil usually causes diarrhea, a side effect most prefer to avoid.
Having sex
If an expectant mom’s body is ready to go into labor, having sex can help. When a woman orgasms, she produces a hormone called oxytocin, which causes the uterus to contract. (Oxytocin is the natural form of Pitocin, the drug frequently used to induce or augment labor in the hospital.) Additionally, semen contains prostaglandins, or hormones, that cause the cervix to soften and thin, making the cervix more ready for labor to begin.