Heart Rate, FetalFetal HeartFetal MonitoringHeart RateCardiotocographyFetal MovementMuscle ContractionFetal DistressHeartPregnancyUmbilical ArteriesUltrasonography, PrenatalFetal HypoxiaGestational AgeFetal DiseasesMagnetocardiographyUltrasonography, DopplerLabor, ObstetricFetusBradycardiaPregnancy Trimester, ThirdIsometric ContractionHeart Defects, CongenitalPregnancy Trimester, FirstMyocardial ContractionEchocardiography, Four-DimensionalPregnancy Trimester, SecondPerinatologyPregnancy OutcomeBlood Flow VelocityUterine ContractionAnalgesia, ObstetricalFetal Growth RetardationAnesthesia, ObstetricalHeart AuscultationBlood PressureApgar ScoreHemodynamicsElectronics, MedicalTocolytic AgentsPrenatal DiagnosisSufentanilHeart FailureMaternal-Fetal ExchangeFetal DevelopmentSheepAnesthesia, EpiduralPregnancy ComplicationsElectrocardiographyCesarean SectionCrown-Rump LengthMyocardiumProspective StudiesMeconiumInfant, NewbornUmbilical CordCardiovascular SystemAutonomic Nervous SystemOxytocicsHeart BlockMuscle, SmoothHeart DiseasesCanrenoic AcidSignal Processing, Computer-AssistedObstetric Labor ComplicationsEchocardiography, Three-DimensionalTime FactorsHeart TransplantationTurner SyndromeAmniotic FluidChromosome DisordersDown SyndromeUltrasonography, Doppler, ColorPulsatile FlowHeart ValvesElectric StimulationDelivery, ObstetricRegional Blood FlowCardiac VolumeTrisomyNeckMuscle, SkeletalBlood Gas AnalysisEchocardiographyDogsSympathetic Nervous SystemAtropineNorepinephrineCalciumOxygenHeart AtriaVasoconstrictionGuinea PigsUterusReproducibility of ResultsSensitivity and SpecificityDose-Response Relationship, DrugMyocytes, CardiacElectrocardiography, AmbulatoryAdrenergic beta-Antagonists