<prompt> IUGR is defined when:Birth weight is below the tenth percentile of the average of gestational ageBirth weight is below the 20 percentile of the average of gestational ageBirth weight is below the 30 percentile of the average of gestational ageWeight of baby is less than 1000 gm  <response>: Ans. is a, i.e. Birth weight is below the tenth percentile of the average of gestational ageRef Dutta Obs. 7e, p 461Intrauterine growth restriction is said to be present in those babies whose birth weight is below the tenth percentile of the average for the gestational age. 