Congenital anomalies are most severe in:

Ans. is a, i.e. Rubella infectionRef. Williams Obs. 23/e, p 1214"Rubella is one of the most teratogenic agents known." Ref. Williams Obs. 23/e, p 1214Rubella causes a number of serious defects in fetus. These defects may occur singly or in combination called Congenital rubella syndrome.