Down SyndromeSyndromeChromosomes, Human, Pair 21Prenatal DiagnosisTrisomyReference StandardsMaternal AgeReference ValuesMetabolic Syndrome XPregnancy Trimester, SecondEstriolPregnancyAmniocentesisLeukemia, Megakaryoblastic, AcuteFetal DiseasesChromosomes, Human, 21-22 and YNephrotic SyndromeInfant, NewbornAbortion, EugenicSjogren's SyndromeIntellectual DisabilityTurner SyndromeKaryotypingAbnormalities, Multiplealpha-FetoproteinsNasal BoneUltrasonography, PrenatalNuchal Translucency MeasurementNondisjunction, GeneticPregnancy, High-RiskPregnancy Trimester, FirstWilliams SyndromeFalse Positive ReactionsPregnancy-Associated Plasma Protein-AMyelodysplastic SyndromesPhenotypeChorionic Gonadotropin, beta Subunit, HumanCushing SyndromeDisease Models, AnimalHeart Defects, CongenitalCase-Control StudiesPaternal AgeAcute Coronary SyndromePolycystic Ovary SyndromeChromosome DisordersRisk FactorsSensitivity and SpecificityDiGeorge SyndromeRetrospective StudiesBiological MarkersGestational AgeHorner SyndromeCraniofacial AbnormalitiesLong QT SyndromePrader-Willi SyndromeMutationStanford-Binet TestBrainTime FactorsHeart Septal DefectsPrevalenceReproducibility of ResultsAlzheimer DiseaseGenetic TestingGuillain-Barre SyndromeProspective StudiesHemolytic-Uremic SyndromeDuodenal ObstructionChorionic GonadotropinCompartment SyndromesGATA1 Transcription FactorPedigreeTourette SyndromeAge FactorsMosaicismAntiphospholipid SyndromeMolecular Sequence DataPorcine Reproductive and Respiratory SyndromeNeckChromosome AberrationsKlinefelter SyndromeCarpal Tunnel SyndromeTreatment Outcome