Also called fetal growth restriction. IUGR describes a condition where an unborn baby is smaller than expected for a fetus of the same gestational age, due to slower than normal growth within the womb. IUGR has many different causes, which may include poor nutrition in the mother, infection, anemia, or problems with the placenta.
Source: Standford n.d. - https://www.stanfordchildrens.org/en/topic/default?id=intrauterine-growt...