1. A method for measuring the amounts of fetal chromosome segments in a maternal blood sample, comprising: obtaining fetal and maternal chromosome segments from cell-free DNA in a maternal blood sample; ligating at least one adapter to the chromosome segments, wherein the at least one adapter comprises a universal amplification sequence; performing universal amplification using universal primers that bind to the universal amplification sequence to generate amplified chromosome segments; performing clonal amplification of the amplified chromosome segments to generate clonally amplified chromosome segments; and measuring the amounts of clonally amplified fetal chromosome segments by performing next generation sequencing, wherein the measuring comprises quantitative allele measurements performed irrespective of allele value.