Nondisjunction, GeneticTrisomyDown SyndromeChromosomes, Human, Pair 21MeiosisAneuploidyCrossing Over, GeneticKaryotypingChromosomes, Human, Pair 18Chromosome DisordersChromosome AberrationsMaternal AgeMosaicismChromosomes, Human, Pair 13Sex ChromosomesChromosomesTranslocation, GeneticChromosomes, Human, 16-18Abnormalities, Radiation-InducedX ChromosomeChromosome SegregationIn Situ Hybridization, FluorescenceRecombination, GeneticPrenatal DiagnosisY ChromosomeChromosome BandingCrosses, GeneticAbnormalities, MultipleNuchal Translucency MeasurementPaternal AgeMonosomyGenetic MarkersDiploidyChromosome MappingPotoroidaeCentromerePregnancyChorionic Gonadotropin, beta Subunit, HumanSex Chromosome AberrationsMitosisChromosomes, FungalChromosomes, Human, 13-15Chromosomes, Human, 6-12 and XChromatidsPregnancy Trimester, FirstSecale cerealeUltrasonography, PrenatalGenetic TechniquesChromosomes, InsectFetal DiseasesNucleolus Organizer RegionPregnancy-Associated Plasma Protein-APregnancy Trimester, SecondNasal BoneChromosomes, Human, 21-22 and Yp-FluorophenylalanineMetaphaseDrosophila melanogasterDermatoglyphicsPregnancy, High-RiskX-RaysAmniocentesisCytogenetic AnalysisSpermatocytesOocytesCrown-Rump LengthMutationMutagensHeterozygoteChromosomes, Human, Pair 8PolyploidyChromosome BreakageHygromycin BChromosome InversionPhosphoribosylglycinamide FormyltransferaseSister Chromatid ExchangeSynaptonemal ComplexChromosomes, Human, Pair 12Chromosomes, Human, 19-20Chorionic Villi SamplingPhenotypeChromosomes, Human, 4-5Chromosomes, Human, Pair 7NeckChromosomes, PlantSpermatozoaPollenAllelesSporesGestational AgeAnaphaseZea maysDrosophilaGenotype