<prompt> Aneuploidy, is the most common genetic abnormality, accounting for up to 50 of clinical miscarriages. All are true about aneuploidy, EXCEPT:30-40 of trisomy 21, fetus die between 12 weeks and 40 weeks50-60 of trisomy 18, fetus die between 12 weeks and 40 weeksOccurrence of triploidy has no relation with the progression of mothers ageIn previous pregnancy with trisomy 21 due to non disjunction, the risk in future pregnancy is .75 higher  <response>: Also known as Edwards syndrome,trisomy 18 has an overall frequency of 1 in 8000 newborns and is three to four times more common in females. As with other aneuploidies, its incidence is much higher in the first trimester, and 85 percent of fetuses die between 10 weeks and term. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. 2010. Chapter 12. Genetics. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong Eds, Williams Obstetrics, 23e. 