TwinsDiseases in TwinsTwins, MonozygoticTwins, ConjoinedTwins, DizygoticTwin Studies as TopicPregnancy, TwinPregnancy, MultipleTissue and Organ ProcurementOrgan TransplantationFetofetal TransfusionMultiple Organ FailurePregnancyOrgan SizeOrgan of CortiOrgan SpecificityTripletsGestational AgeEnvironmentPregnancy Reduction, MultifetalVomeronasal OrganInfant, NewbornFetal DeathChorionPregnancy OutcomeSubfornical OrganUltrasonography, PrenatalGenetics, BehavioralBirth WeightPhenotypeGene-Environment InteractionPelvic Organ ProlapseTwinning, MonozygoticRegistriesTissue DonorsSocial EnvironmentFetoscopyTissue and Organ HarvestingBrain DeathLiverQuadrupletsRisk FactorsPolyhydramniosGenetic Predisposition to DiseaseDenmarkDermatoglyphicsTissue DistributionReproductive Techniques, AssistedCohort StudiesKidneyTime FactorsEnamel OrganSwedenTwin StudyModels, GeneticFertilization in VitroBirth OrderEmbryo Transfer