Obstetric Labor, PrematurePremature BirthPregnancyInfant, PrematurePregnancy OutcomeInfant, NewbornGestational AgeChorioamnionitisFetal Membranes, Premature RuptureInfant, Low Birth WeightPregnancy ComplicationsDelivery, ObstetricPregnancy Trimester, SecondCervical RipeningDrug Delivery SystemsCervix UteriPregnancy Trimester, ThirdAmniotic FluidUterine Cervical IncompetencePregnancy Complications, InfectiousTocolysisRisk FactorsInfant, Premature, DiseasesInfant, Small for Gestational AgeUterine MonitoringPregnancy, High-RiskTocolytic AgentsBirth WeightExtraembryonic MembranesVaginosis, BacterialFetal Growth RetardationCesarean SectionParityStillbirthPregnancy, MultipleCervical Length MeasurementUltrasonography, PrenatalFetal DeathProspective StudiesMaternal AgePregnancy, TwinPre-EclampsiaBetamethasonePlacentaTerm BirthPerinatal MortalityPlacenta DiseasesPrimary PreventionInfant MortalityUterine ContractionCohort StudiesAbruptio PlacentaePrenatal CareGravidityUreaplasma InfectionsCerclage, CervicalTwinsHypertension, Pregnancy-InducedLabor, ObstetricVaginaPlacenta PreviaUterine HemorrhageAbortion, SpontaneousLogistic ModelsRetrospective StudiesInfant, Very Low Birth WeightPregnancy Trimester, FirstOdds RatioHydroxyprogesteronesPregnancy Complications, CardiovascularAmniocentesisApgar ScoreUterusCardiotocographyPerinatal CareTripletsAmnionUreaplasma urealyticumWomen, WorkingFetusRisk AssessmentUnited StatesMaternal ExposureFetal Organ MaturityIntensive Care Units, NeonatalInfant, Extremely PrematureBirth CertificatesMaternal WelfareAdministration, IntravaginalAntitrichomonal AgentsCongenital AbnormalitiesTime FactorsSecondary PreventionCenters for Disease Control and Prevention (U.S.)RiskCase-Control StudiesLabor, InducedObstetric Labor ComplicationsPregnancy Complications, ParasiticMultiple Birth Offspring