<prompt> A 35 year old female, mother of a Downs syndrome child, became pregnant. Amniocentesis is done to rule out Downs syndrome in the second child. What is the appropriate time for doing amniocentesis?6-Apr12-Aug17-Dec20-28  <response>: Amniocentesis generally is carried out at 15 to 17 weeks of gestation but can be offered earlier 12-14 weeks. The underlying risk of amniocentesis when performed at 15 weeks of gestation and beyond is increased risk of miscarriage. This risk is estimated at 1 in 200 0.5. Ref: Manipalviratn S., Trivax B., Huang A. 2007. Chapter 5. Genetic Disorders Sex Chromosome Abnormalities. In A.H. DeCherney, L. Nathan Eds,CURRENT Diagnosis Treatment Obstetrics Gynecology, 10e. 