TwinsDiseases in TwinsTwins, MonozygoticTwins, ConjoinedTwins, DizygoticTwin Studies as TopicPregnancy, TwinVentricular Function, LeftVentricular Dysfunction, LeftHypertrophy, Left VentricularPregnancy, MultipleAtrial Function, LeftFetofetal TransfusionHeart VentriclesPregnancyEchocardiographyTripletsStroke VolumeHeart AtriaGestational AgeEnvironmentInfant, NewbornPregnancy Reduction, MultifetalDiastoleUltrasonography, PrenatalMyocardial ContractionFetal DeathPregnancy OutcomeHeartHemodynamicsChorionElectrocardiographyFunctional LateralitySystoleGenetics, BehavioralVentricular RemodelingBirth WeightMyocardiumTime FactorsHeart FailureGene-Environment InteractionHypoplastic Left Heart SyndromeRisk FactorsTwinning, MonozygoticRegistriesDogsBlood PressureTreatment OutcomeMyocardial InfarctionFollow-Up StudiesFetoscopySocial EnvironmentCoronary CirculationProspective StudiesCardiac VolumeRetrospective StudiesCohort StudiesAnalysis of VarianceVentricular FunctionVentricular PressurePhenotypeQuadrupletsHeart AneurysmDenmarkCardiomyopathy, DilatedDermatoglyphicsPolyhydramniosGenetic Predisposition to DiseaseMitral ValveCardiac CatheterizationHeart RateCoronary VesselsTomography, X-Ray ComputedCardiac Pacing, ArtificialHeart-Assist DevicesReproductive Techniques, AssistedSwedenBlood Flow VelocityCardiomyopathiesPredictive Value of TestsAtrial FibrillationEchocardiography, TransesophagealImage Processing, Computer-AssistedTwin StudyFertilization in VitroBirth OrderEmbryo Transfer