Analgesia, EpiduralAnalgesia, ObstetricalAnalgesiaAnalgesia, Patient-ControlledAnesthesia, EpiduralBupivacaineLabor PainLabor, ObstetricAnalgesics, OpioidPain, PostoperativeAnesthetics, LocalAnesthesia, ObstetricalFentanylSufentanilPain MeasurementLabor Stage, FirstAmidesCesarean SectionMeperidineObstetric Labor ComplicationsMorphinePregnancyNerve BlockDelivery, ObstetricLabor Stage, SecondPostoperative Nausea and VomitingThoracotomyExtraction, ObstetricalAnesthesia, GeneralDouble-Blind MethodHydromorphone