Pregnancy TrimestersPregnancy Trimester, FirstPregnancy Trimester, ThirdPregnancy Trimester, SecondPregnancyPregnancy ComplicationsPregnancy OutcomePregnancy, AnimalUltrasonography, PrenatalPregnancy, EctopicGestational AgeUltrasonographyPregnancy Complications, CardiovascularPregnancy RateAbortion, SpontaneousPregnancy Complications, NeoplasticPregnancy, MultipleUltrasonicsPregnancy in DiabeticsPregnancy Complications, InfectiousUltrasonic TherapyPregnancy TestsInfant, NewbornPlacentaFetal DiseasesPregnancy, TubalHigh-Intensity Focused Ultrasound AblationPre-EclampsiaPregnancy, High-RiskAbortion, InducedUltrasonography, InterventionalPrenatal DiagnosisPregnancy in AdolescencePregnancy ProteinsMicrobubblesFetal DeathProspective StudiesPregnancy Complications, HematologicTrophoblastsFetusFetal DevelopmentFetal Growth RetardationPregnancy, UnplannedUltrasonography, DopplerUterusPrenatal CareCrown-Rump LengthBirth WeightChorionic VilliMaternal-Fetal ExchangeUltrasonography, Doppler, ColorPregnancy, TwinPregnancy, UnwantedDeciduaPrenatal Exposure Delayed EffectsAbnormalities, Drug-InducedMaternal AgeAmniotic FluidParityPregnancy, ProlongedAbortifacient Agents, NonsteroidalPregnancy Complications, ParasiticTransducersSensitivity and SpecificityCesarean SectionHypertension, Pregnancy-InducedCongenital AbnormalitiesPremature BirthMaternal ExposureAbortion, TherapeuticChorionic Gonadotropin, beta Subunit, HumanPregnancy, AbdominalFertilization in VitroFetal HeartDown SyndromeUterine HemorrhageRetrospective StudiesEmbryo ImplantationPregnancy MaintenanceObstetric Labor, PrematureRisk FactorsAmniocentesisEmbryo TransferAbortion, HabitualImaging, Three-DimensionalPlacental CirculationChorionic GonadotropinReproducibility of ResultsPlacenta DiseasesTime FactorsTwinsLabor, ObstetricPlacentationMisoprostolDiabetes, GestationalCohort StudiesUltrasonography, Doppler, PulsedHydatidiform MoleInfant, Low Birth WeightPredictive Value of Tests