Ultrasonography, Doppler, ColorUltrasonography, Doppler, PulsedUltrasonography, DopplerEchocardiography, Doppler, ColorBlood Flow VelocityRegional Blood FlowDoppler EffectUltrasonographyEchocardiography, DopplerUltrasonography, Doppler, TranscranialMitral Valve InsufficiencyUltrasonography, PrenatalUltrasonicsPulsatile FlowUmbilical ArteriesEchocardiography, Doppler, PulsedPregnancyUltrasonography, InterventionalLaser-Doppler FlowmetryUltrasonic TherapyPlacental CirculationSensitivity and SpecificityCerebrovascular CirculationProspective StudiesImaging, Three-DimensionalMicrobubblesHigh-Intensity Focused Ultrasound AblationReproducibility of ResultsVascular ResistanceMiddle Cerebral ArteryGestational AgeEchoencephalographyFetal DiseasesPregnancy Trimester, SecondObserver VariationPredictive Value of TestsUltrasonography, Doppler, DuplexOphthalmic ArteryArteriesContrast MediaCerebral ArteriesFlow CytometryFetal Growth RetardationUterusBlood PressureFetal MonitoringHeart Rate, FetalIntracranial Embolism and ThrombosisRheologyTransducersUterine ArteryFemoral ArteryPortal VeinAdnexal DiseasesFetal HeartEchocardiographyLegBrachial ArteryAngiographyCoronary CirculationCarotid StenosisCardiac OutputHemodynamicsMitral ValveCarotid Artery DiseasesPregnancy Trimester, ThirdEmbolism, AirTime FactorsIntracranial EmbolismCarotid ArteriesForearmAdnexa UteriConstriction, PathologicInfant, NewbornArterial Occlusive DiseasesReference ValuesBlood CirculationPregnancy Trimester, FirstHyperemiaFetusModels, CardiovascularImage Interpretation, Computer-AssistedPregnancy OutcomeUltrasonography, MammarySplenic ArteryPlacenta DiseasesHeart RateCarotid Artery, InternalImage EnhancementUterine HemorrhageValsalva ManeuverCardiac CatheterizationTreatment OutcomeDiastoleMesenteric Artery, SuperiorFeasibility StudiesTomography, X-Ray ComputedVasodilationEquipment DesignRetrospective Studies