Bed RestMothersHead-Down TiltWeightlessness SimulationWeightlessness CountermeasuresRestCardiovascular DeconditioningSpace FlightBedsTreatment OutcomeWeightlessnessOutcome Assessment (Health Care)Orthostatic IntolerancePregnancyPregnancy OutcomeLower Body Negative PressureTime FactorsInfant, NewbornMother-Child RelationsRetrospective StudiesBed OccupancyFollow-Up StudiesProspective StudiesExerciseSupine PositionEarly AmbulationMuscular AtrophyMuscle, SkeletalRisk FactorsPlasma VolumeHypotension, OrthostaticOutcome and Process Assessment (Health Care)Breast FeedingHypovolemiaCohort StudiesPrognosisImmobilizationVascular CapacitanceAmino Acids, EssentialPregnancy ComplicationsSpinal Puncture