Down SyndromePrevalenceSyndromeChromosomes, Human, Pair 21Prenatal DiagnosisTrisomyMaternal AgeMetabolic Syndrome XPregnancy Trimester, SecondPregnancyEstriolRisk FactorsInfant, NewbornCross-Sectional StudiesAmniocentesisLeukemia, Megakaryoblastic, AcuteFetal DiseasesChromosomes, Human, 21-22 and YNephrotic SyndromeAbortion, EugenicSjogren's SyndromeIntellectual DisabilityTurner SyndromeAge FactorsKaryotypingAbnormalities, Multiplealpha-FetoproteinsRetrospective StudiesCase-Control StudiesNasal BoneNuchal Translucency MeasurementAge DistributionUltrasonography, PrenatalPregnancy, High-RiskNondisjunction, GeneticPregnancy Trimester, FirstWilliams SyndromePhenotypeQuestionnairesBrazilProspective StudiesSex DistributionFalse Positive ReactionsMyelodysplastic SyndromesHeart Defects, CongenitalPregnancy-Associated Plasma Protein-AChorionic Gonadotropin, beta Subunit, HumanCushing SyndromePolycystic Ovary SyndromeSex FactorsDisease Models, AnimalCohort StudiesPaternal AgeIncidenceAcute Coronary SyndromeTime FactorsUnited StatesChromosome DisordersMutationGenotypeMass ScreeningComorbidityBiological MarkersLogistic ModelsSeverity of Illness IndexHealth SurveysDiGeorge SyndromeGenetic TestingIndiaFollow-Up StudiesLong QT SyndromeCraniofacial AbnormalitiesPrader-Willi SyndromePolymerase Chain ReactionHorner SyndromePedigreeStanford-Binet TestAlzheimer DiseaseHeart Septal DefectsSensitivity and SpecificityGestational AgeTreatment OutcomeGuillain-Barre SyndromeHemolytic-Uremic SyndromeRisk AssessmentSocioeconomic FactorsAntiphospholipid SyndromeBrainTourette SyndromeDuodenal ObstructionChinaAbortion, InducedObesityCompartment SyndromesNeckGATA1 Transcription FactorCongenital AbnormalitiesChorionic GonadotropinCarpal Tunnel SyndromeMosaicism