Anesthesia, SpinalAnalgesia, ObstetricalVersion, FetalAnalgesiaInjections, SpinalAnalgesia, EpiduralAnalgesics, OpioidLabor, ObstetricSpinal CordPain MeasurementLabor, InducedLabor PainAnalgesia, Patient-ControlledSpinal Cord InjuriesLabor OnsetObstetric Labor, PrematurePain, PostoperativeBupivacaineObstetric Labor ComplicationsMorphineAnesthetics, LocalTrial of LaborPregnancyFentanylAnalgesicsAcupuncture AnalgesiaAnesthesia, EpiduralCesarean SectionPainSpinal NervesMeperidineAnesthesia, ObstetricalSufentanilSpinal Cord DiseasesSpinal Nerve RootsDelivery, ObstetricLabor PresentationSpinal Cord NeoplasmsSpinal CanalSpinal DiseasesSpinal Cord CompressionNerve BlockSpinal NeoplasmsLabor Stage, ThirdSpinal StenosisSpinal FusionAmidesDouble-Blind MethodOxytocicsPain ThresholdNaloxoneTramadolSpinal InjuriesAnalgesics, Non-NarcoticMuscular Atrophy, SpinalGanglia, SpinalHyperalgesiaMyometriumUterine ContractionSpinal Cord IschemiaDrug ToleranceClonidinePostoperative Nausea and VomitingRats, Sprague-DawleyReceptors, Opioid, muLidocainePain ManagementApgar ScoreInterpleural AnalgesiaPosterior Horn CellsTerm BirthTocolytic AgentsAnesthesia, GeneralCervical RipeningThoracic VertebraeTime FactorsMotor NeuronsProspective StudiesSpineKetorolacFetal MonitoringHematoma, Epidural, SpinalParityNociceptorsAmnionConscious SedationLabor Stage, FirstParaplegiaParturitionTuberculosis, SpinalPregnancy OutcomeReceptors, OpioidHydromorphoneFemoral NerveLaminectomyKetamineAnesthesia, CaudalLumbosacral RegionNarcotic AntagonistsExtraembryonic Membranes