Down SyndromeSyndromeChromosomes, Human, Pair 21Prenatal DiagnosisTrisomyMaternal AgeMetabolic Syndrome XEstriolPregnancy Trimester, SecondPregnancyAmniocentesisLeukemia, Megakaryoblastic, AcuteFetal DiseasesChromosomes, Human, 21-22 and YNephrotic SyndromeSjogren's SyndromeAbortion, EugenicInfant, NewbornIntellectual DisabilityTurner SyndromeKaryotypingAbnormalities, Multiplealpha-FetoproteinsNasal BoneNuchal Translucency MeasurementRisk FactorsNondisjunction, GeneticUltrasonography, PrenatalPregnancy, High-RiskPrevalencePregnancy Trimester, FirstSeverity of Illness IndexTreatment OutcomeWilliams SyndromeCase-Control StudiesProspective StudiesDisease Models, AnimalPhenotypeMyelodysplastic SyndromesRetrospective StudiesPregnancy-Associated Plasma Protein-AChorionic Gonadotropin, beta Subunit, HumanQuestionnairesCushing SyndromeTime FactorsFalse Positive ReactionsDepressionHeart Defects, CongenitalAcute Coronary SyndromeFollow-Up StudiesPaternal AgePolycystic Ovary SyndromeSymptom AssessmentChromosome DisordersDiGeorge SyndromeHorner SyndromeBrainBiological MarkersAge FactorsCraniofacial AbnormalitiesMutationPrader-Willi SyndromeAlzheimer DiseaseLong QT SyndromeStanford-Binet TestGuillain-Barre SyndromeTourette SyndromeHeart Septal DefectsDuodenal ObstructionGenetic TestingPedigreeHemolytic-Uremic SyndromeCarpal Tunnel SyndromeCompartment SyndromesCross-Sectional StudiesNeckGATA1 Transcription FactorAntiphospholipid SyndromeChorionic GonadotropinGestational AgeMosaicismCohort StudiesKlinefelter SyndromePorcine Reproductive and Respiratory SyndromeParents