Bed RestTwinsDiseases in TwinsTwins, MonozygoticTwins, ConjoinedTwins, DizygoticHead-Down TiltWeightlessness SimulationWeightlessness CountermeasuresRestCardiovascular DeconditioningSpace FlightTwin Studies as TopicBedsWomenWomen's HealthWeightlessnessPregnancy, TwinOrthostatic IntoleranceLower Body Negative PressurePregnancyTime FactorsPregnancy, MultipleBed OccupancyPregnant WomenBattered WomenMuscle, SkeletalSupine PositionMuscular AtrophyPlasma VolumeEarly AmbulationExerciseHypotension, OrthostaticPregnancy OutcomeWomen's Health ServicesHypovolemiaRisk FactorsSex FactorsCohort StudiesVascular CapacitanceWomen's RightsAmino Acids, EssentialUterine Cervical IncompetenceImmobilizationInfant, NewbornFetofetal TransfusionQuestionnaires