Usually, when the woman is officially in labor and regular contractions occur, medication can be injected for labor analgesia, not limited to when the uterine opening must be up to 2-3 fingers. Painless labor is generally referred to as labor analgesia, which refers to various ways to reduce the pain caused by labor. Common painless delivery methods include pharmacological analgesia and non-pharmacological analgesia, and currently pharmacological analgesia is mainly used in the form of intrathecal anesthesia. In order to enhance safety, most hospitals will only administer analgesic drugs when the pregnant woman is officially in labor and regular contractions occur. The premise of labor analgesia is to ensure the safety of the life of the pregnant woman and the fetus. The injection of analgesic drugs can not be completely painless, but can only reduce the pain to a certain extent. Before the injection of analgesic drugs, the mother needs to complete the examination to find out whether she is allergic to the analgesic drugs, so as to avoid allergic reactions.