Medical Genetics C Mortallity/Morbidity Approximately 95%o of conceptuses with trisomy 18 die in embryonic or fetal life 5-10% of affected children survive beyond the first year of life The high mortality rate is usually due to the presence of cardiac and renal malformations, feeding difficulties, sepsis and apnea caused by CNs defects Severe psychomotor and growth retardation are invariably present for those who survive beyond infancyMedical Genetics C. Mortality/Morbidity • Approximately 95% of conceptuses with trisomy 18 die in embryonic or fetal life; 5-10% of affected children survive beyond the first year of life. • The high mortality rate is usually due to the presence of cardiac and renal malformations, feeding difficulties, sepsis, and apnea caused by CNS defects. • Severe psychomotor and growth retardation are invariably present for those who survive beyond infancy