 Half of embryonic miscarriages (25% of all miscarriages) have an aneuploidy (abnormal number of chromosomes).Common chromosome abnormalities found in miscarriages include an autosomal trisomy (22–32%), monosomy X (5–20%), triploidy (6–8%), tetraploidy (2–4%), or other structural chromosomal abnormalities (2%).Genetic problems are more likely to occur with older parents; this may account for the higher rates observed in older women.