Premature BirthInfant, PrematureInfant, NewbornPregnancyObstetric Labor, PrematureBirth WeightInfant, Low Birth WeightGestational AgePregnancy OutcomeCongenital AbnormalitiesAbortion, VeterinaryInfant, Premature, DiseasesPregnancy ComplicationsBronchopulmonary DysplasiaFetal DeathAbortion, SpontaneousInfant MortalityInfant, Small for Gestational AgePregnancy Complications, InfectiousRespiratory Distress Syndrome, NewbornAnimals, NewbornBirth RateRisk FactorsRetrospective StudiesBirth OrderBirth CertificatesBirth IntervalsBirth InjuriesMultiple Birth OffspringMaternal AgeDelivery, ObstetricVaginal Birth after CesareanParityCohort Studies