This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Considerations - Infectious Diseases, Subject name: Pediatrics
Risk of congenital defects in a baby is maximum, if the gestational age at the time of maternal rubella infection is: 
Select and explain. 
A. < 11 weeks, B. 11-12 weeks, C. 13-14 weeks, D. 15-16 weeks
A: < 11 weeks
Answer: A: < 11 weeks 
Explanation: a. < 11 weeks(Ref: Nelson's 20/e p 1548-1551)Risk of congenital defects in a baby is maximum, if mother acquires Rubella in the first trimester (before 11 weeks).