Bed RestMothersHead-Down TiltWeightlessness SimulationWeightlessness CountermeasuresRestCardiovascular DeconditioningSpace FlightBedsWeightlessnessOrthostatic IntoleranceLower Body Negative PressurePregnancyMother-Child RelationsBed OccupancyInfant, NewbornSupine PositionMuscular AtrophyExercisePlasma VolumeMuscle, SkeletalEarly AmbulationTime FactorsHypotension, OrthostaticHypovolemiaVascular CapacitanceBreast FeedingAmino Acids, EssentialImmobilization