<prompt> Chorionic villous sampling done before 10 weeks may result in:Fetal lossFetomaternal hemorrhageOromandibular limb defectsSufficient material not obtained  <response>: Ans. is c, i.e. Oromandibular limb defectsRef. Williams Obs. 21e, p 990; 22e, p 330, 23e, p 300Chorionic villous sampling is usually performed at 10-13 weeks and is associated with several complications but studies suggests that limb reduction and oromandibular limb hypo genesis is more common, if CVS is done before 9 weeks. So, CVS is done after 9 weeks because it is more safe. --Williams Obs. 21e, p 990The frequency of oromandibular limb hypogenesis, however was increased after CVS, when the procedure was performed before 9 weeks. --Williams Obs. 22e, p 330It was shown that limb reduction defects were associated with CVS performed earlier in gestation--typically around 7 weeks. --Williams 23e, p 300 