Fetal HeartHeart Rate, FetalHeartUltrasonography, DopplerFetal MonitoringUltrasonography, Doppler, ColorCardiotocographyUltrasonography, PrenatalHeart RateDoppler EffectPregnancyHeart Defects, CongenitalUltrasonography, Doppler, PulsedEchocardiography, Four-DimensionalEchocardiography, Doppler, ColorBlood Flow VelocityUmbilical ArteriesGestational AgeFetal DiseasesFetal MovementEchocardiography, Doppler, PulsedFetal DistressUltrasonography, Doppler, TranscranialFetal HypoxiaFetusHeart FailurePregnancy Trimester, SecondEchocardiography, Three-DimensionalHeart BlockHeart DiseasesCanrenoic AcidPregnancy Trimester, ThirdPregnancy Trimester, FirstEchocardiographyHeart ValvesMagnetocardiographyPulsatile FlowHeart TransplantationUltrasonographyLaser-Doppler FlowmetryFetal Growth RetardationProspective StudiesMyocardiumLabor, ObstetricPlacental CirculationCardiac VolumeHemodynamicsPregnancy OutcomeRegional Blood FlowSensitivity and SpecificityBradycardiaMyocardial ContractionReproducibility of ResultsFetal DevelopmentHeart AtriaInfant, NewbornPrenatal DiagnosisDiastoleAbortion, ThreatenedVentricular Function, LeftSheepMaternal-Fetal ExchangeSystolePregnancy, High-RiskApgar ScoreHeart SeptumMyocytes, CardiacPredictive Value of TestsCrown-Rump LengthObserver VariationReference ValuesPregnancy ComplicationsHeart VentriclesFeasibility StudiesTime FactorsHeart Function TestsUmbilical CordVentricular Dysfunction, LeftElectronics, MedicalPerinatologyStroke VolumeAnalgesia, ObstetricalHeart AuscultationTocolytic AgentsCardiomegalyUterusCesarean SectionAnesthesia, ObstetricalVascular ResistanceMitral ValveMyocardial IschemiaSheep, DomesticDown SyndromeFetal DeathHeart Arrest, InducedSufentanilUltrasonography, Doppler, DuplexRisk FactorsImage EnhancementImage Processing, Computer-Assisted