This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in Obstetrics, Subject name: Gynaecology & Obstetrics
Chorionic villous sampling done before 10 weeks may result in: 
Select and explain. 
A. Fetal loss, B. Fetomaternal hemorrhage, C. Oromandibular limb defects, D. Sufficient material not obtained
C: Oromandibular limb defects
Answer: C: Oromandibular limb defects 
Explanation: Ans. is c, i.e. Oromandibular limb defectsRef. Williams Obs. 21/e, p 990; 22/e, p 330, 23/e, p 300"Chorionic 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. 21/e, p 990"The frequency of oromandibular limb hypogenesis, however was increased after CVS, when the procedure was performed before 9 weeks." --Williams Obs. 22/e, p 330"It was shown that limb reduction defects were associated with CVS performed earlier in gestation--typically around 7 weeks." --Williams 23/e, p 300