Uterine ContractionFetal HeartHeart Rate, FetalMyometriumTocolytic AgentsPregnancyMuscle ContractionOxytocinHeartRitodrineLabor, ObstetricUterusAbortifacient AgentsFetal MonitoringLabor Stage, FirstCoixCardiotocographyUltrasonography, PrenatalObstetric Labor, PrematureUterine MonitoringOxytocicsGestational AgeHeart RateReceptors, OxytocinParturitionPregnancy Trimester, ThirdAroclorsIsometric ContractionLindaneLabor OnsetHeart Defects, CongenitalEchocardiography, Four-DimensionalFetusVasotocinPregnancy Trimester, SecondMyocardial ContractionFetal MovementDinoprostPregnancy, AnimalUltrasonography, DopplerFetal DiseasesLabor, InducedFetal DistressFetal HypoxiaRats, Sprague-DawleyProstaglandins FMuscle, SmoothCesarean SectionUmbilical ArteriesCervix UteriMifepristoneDiltiazemHeart FailureExtraembryonic MembranesNifedipineAmniotic FluidDose-Response Relationship, DrugCalciumBlood Flow VelocityTime FactorsHeart BlockMyocardiumCanrenoic AcidProgesteroneEchocardiography, Three-DimensionalHeart DiseasesProstaglandinsEstrusMagnetocardiographyGap JunctionsHeart TransplantationAlbuterolHeart ValvesPregnancy Trimester, FirstPlacentaRats, Inbred StrainsPolychlorinated BiphenylsCardiac VolumeElectric StimulationMuscle, SkeletalGuinea PigsBradycardiaVasoconstrictionEchocardiographyMyocytes, CardiacIsotonic ContractionHeart AtriaSheepPregnancy OutcomeOvariectomyAbortion, ThreatenedFetal DevelopmentEstradiol