Maternal AgeGestational AgeInfant, Small for Gestational AgePregnancyInfant, NewbornBirth WeightInfant, PrematurePregnancy OutcomeUltrasonography, PrenatalDown SyndromePremature BirthBirth OrderInfant, Low Birth WeightPregnancy, High-RiskPaternal AgePregnancy ComplicationsPregnancy Trimester, FirstPregnancy Trimester, SecondParityCrown-Rump LengthAmniocentesisFetal Growth RetardationRisk FactorsPrenatal DiagnosisInfant, Premature, DiseasesInfant MortalityPregnancy Trimester, ThirdObstetric Labor, PrematureCongenital AbnormalitiesFetal DeathFetusBirth CertificatesFetal DiseasesFetal DevelopmentCesarean SectionAbortion, SpontaneousInfant, Very Low Birth WeightProspective StudiesTwinsPrimary PreventionCohort StudiesStillbirthPrenatal CareTrisomyDelivery, ObstetricTerm BirthPregnancy, MultipleAmniotic FluidApgar ScorePre-EclampsiaRetrospective StudiesMothersNuchal Translucency MeasurementIntensive Care Units, NeonatalPerinatal MortalityChromosome DisordersChild DevelopmentNondisjunction, GeneticLogistic ModelsAneuploidyFetal MacrosomiaPlacentaChorionic Gonadotropin, beta Subunit, HumanGastroschisisFetal HeartLive BirthPrenatal Exposure Delayed EffectsCase-Control StudiesMaternal ExposurePregnancy-Associated Plasma Protein-ARegression AnalysisInfant, Newborn, DiseasesRetinopathy of PrematurityFetal WeightReference ValuesRespiratory Distress Syndrome, NewbornPregnancy, TwinHernia, UmbilicalFetal BloodTripletsFetal MortalityFetal Membranes, Premature RuptureOdds RatioDiabetes, GestationalHeart Rate, FetalHypertension, Pregnancy-InducedBody HeightRegistriesObstetric Labor ComplicationsUmbilical ArteriesIncidenceSocioeconomic FactorsUnited StatesPerinatal CareSecondary PreventionCenters for Disease Control and Prevention (U.S.)Bronchopulmonary DysplasiaEmbryonic and Fetal DevelopmentDevelopmental DisabilitiesFertilization in Vitro