During labor, uterine contractions compress uterine blood vessels, causing uterine ischemia. As the cervix dilates, muscles thin and ligaments stretch, naturally altering nerve endings in these tissues. Additionally, the fetus exerts pressure on the birth canal, contributing to the intense pain experienced by the mother.
Currently, two primary methods of labor analgesia are commonly used: one is pharmacological, employing anesthetics or analgesics to achieve pain relief—this is what we now refer to as painless childbirth. The other is non-pharmacological, utilizing prenatal training and guidance on breathing techniques during uterine contractions to alleviate labor pain.Massaging painful areas during labor or utilizing traditional Chinese medicine techniques like acupuncture can also alleviate labor pain to varying degrees, falling under non-pharmacological methods.
Pharmacological pain relief encompasses multiple approaches, including systemic medication, regional anesthesia, and inhalation anesthesia.Currently, two primary methods are commonly used in clinical practice:
One is spinal-epidural analgesia. This includes epidural block and combined spinal-epidural block. When cervical dilation reaches 3 cm and the mother's pain tolerance reaches its limit, an anesthesiologist injects a low-concentration local anesthetic into the subarachnoid space or epidural space at the mother's waist.Pain relief is achieved through intermittent injections or continuous delivery via an infusion pump, lasting until delivery is complete. The anesthetic concentration is approximately one-fifth that used for cesarean section anesthesia. This lower concentration ensures rapid onset, strong controllability, and high safety. This painless delivery method is currently the most widely used and effective in major hospitals. The mother remains conscious, able to actively cooperate and participate throughout the delivery process.
Another method is nitrous oxide analgesia. Nitrous oxide, also known as laughing gas, is an inhalation anesthetic. This gas has a slightly sweet taste. During labor analgesia, it is inhaled mixed with oxygen at a specific ratio. It has no significant inhibitory effect on respiration or circulation and causes no noticeable impact on the uterus or fetus.After inhaling the mixture, analgesic effects occur within tens of seconds and subside within minutes after cessation. Under the guidance of midwives, it is easy to master. It allows mothers to remain conscious, cooperate well with doctors, and shorten labor duration. However, in clinical practice, some mothers may experience inadequate pain relief.