Born with a normal height, weight, head circumference, and body mass index; being neither abnormally large nor abnormally small at birth. Because pregnancies sometimes end before 38 weeks or after 42 weeks, the judgment of what is the appropriate size for a newborn infant is adjusted to reflect the number of weeks that the mother was pregnant and the sex of the child. Babies born after a pregnancy of 38 to 42 weeks’ duration are AGA if they weigh between 2.5 and 4 kg.