1. A method for the detection of a fetal chromosomal aneuploidy in a pregnant female comprising i) receiving a biological sample from said pregnant female, ii) preparing nucleic acids from said biological sample, iii) amplifying a selected set of target DNA sequences in at least one quantitative multiplex PCR reaction wherein at least one amplified DNA sequence comprises at least one SNP for which the female is heterozygous, iv) sequencing of the amplified target DNA sequences, and v) calculating the sum of read counts for all amplified DNA sequences of a suspected chromosomal aneuploidy followed by normalization, against the sum of read counts for all amplified DNA sequences of a reference chromosome from said biological sample to determine by statistical methods a set score indicative for the presence of a fetal chromosomal aneuploidy.