<prompt> The best period of gestation to carry out chorion villous biopsy for prenatal diagnosis is?8-10 weeks10-12 weeks12-14 weeks14-16 weeks  <response>: Chorionic villus sampling CVS is carried out transcervical between 10-12 weeks and trans-abdominal from 10 weeks to term. Ref:Textbook of Gynecology By D C Dutta, 5th Edition, Page 315 