Premature BirthAbortion, HabitualAbortion, SpontaneousPregnancyObstetric Labor, PrematureInfant, PrematureInfant, NewbornPregnancy OutcomeGestational AgeBirth WeightInfant, Low Birth WeightPregnancy ComplicationsAbortion, ThreatenedPregnancy Trimester, FirstBirth RateFetal Membranes, Premature RuptureCerclage, CervicalAbortion, IncompleteUterine Cervical IncompetenceStillbirthInfant, Premature, DiseasesMaternal AgeInfant, Small for Gestational AgeFetal DeathInfant MortalityChorioamnionitisPregnancy, High-RiskCervical Length MeasurementRisk FactorsPregnancy Trimester, SecondBirth CertificatesPrenatal CareTerm BirthAbortion, MissedCervix UteriPregnancy Complications, InfectiousPregnancy, MultipleCohort StudiesInfant, Extremely PrematureTocolytic AgentsLive BirthHistocompatibility, Maternal-FetalParityCongenital AbnormalitiesDilatation and CurettageGestational SacProspective StudiesBirth IntervalsAmniotic FluidAdministration, IntravaginalBirth OrderDelivery, ObstetricVaginosis, BacterialUltrasonography, PrenatalCesarean SectionCase-Control StudiesAbortion, InducedInfertility, FemaleOdds RatioFetal Growth RetardationMaternal ExposureLogistic ModelsPregnancy Trimester, ThirdUterine HemorrhagePerinatal CareRetrospective StudiesPre-EclampsiaRespiratory Distress Syndrome, NewbornInfant, Very Low Birth WeightMultiple Birth OffspringTwinsHydroxyprogesteronesDevelopmental DisabilitiesPlacentaReproductive Techniques, AssistedCervical RipeningBronchopulmonary DysplasiaMaternal WelfareLabor, InducedIntensive Care Units, NeonatalTripletsProgestinsFertilization in VitroCrown-Rump LengthChild DevelopmentIntensive Care, NeonatalPreconception CareUterusPlacenta DiseasesExtraembryonic MembranesTocolysisPregnancy RateMothersVaginaGravidityPregnancy, TwinParturitionSocioeconomic FactorsInfant CareLabor, Obstetric