A Review of the Potential Therapeutic Application of Vagus Nerve Stimulation During Childbirth
The goal of this research is to show that transcutaneous Vagus nerve stimulation (tVNS) should be investigated as a possible modality for increasing endogenous release of oxytocin during childbirth. There have been many great advances made in the practice of modern obstetrics in the last century. The 1900s saw the discovery, isolation, and subsequent widespread use of the hormone oxytocin as an agent to prevent postpartum hemorrhage and to initiate or quicken labor during childbirth. There are significant risks to the fetus when synthetic oxytocin is used. While the medical administration of oxytocin during labor was being popularized, there was also research being conducted on its physiologic mechanism in labor. A popular idea is that uterine contractions initiate a positive feedback mechanism by triggering a neural pathway that stimulates the release of oxytocin from the pituitary gland, and that the oxytocin then strengthens the contractions which leads to more oxytocin being released, and so on. The use of labor analgesia also became widely used in the 1900s, and by midcentury methods had been described for administering analgesics into the epidural space of the spinal cord. Currently, the epidural is considered the gold standard in labor analgesia. However, there is some evidence that epidural analgesia may inhibit the oxytocin release mechanism by blocking the neural input needed to stimulate it, as women who have had an epidural tend to require synthetic oxytocin infusion more often than women who have not. Research on women with complete spinal cord injury has shown that the Vagus nerves provide an alternate neural pathway from the female reproductive system to the area in the brain that stimulates oxytocin release. It has also been shown that electrical stimulation of the Vagus nerve increases plasma oxytocin levels. Implantable VNS systems are impractical for a single use in pregnant women and may be why VNS has not been explored in obstetrics. However, if a noninvasive transcutaneous method is found to elicit the same response as traditional VNS then it might provide a clinically relevant alternative to using synthetic oxytocin during labor.