Intrauterine growth restriction, or IUGR, is when a baby in the womb (a fetus) does not grow as expected. The baby is not as big as would be expected for the stage of the mother's pregnancy. This timing is known as an unborn baby's "gestational age." Causes of intrauterine growth restriction vary but include placenta abnormalities, high blood pressure in the mother, infections and smoking or alcohol abuse. With this condition, a baby is born weighing less than 90 percent of other babies at the same gestational age. Ultrasounds during pregnancy help monitor a baby's weight. Depending on the results, the baby may need to be delivered early. Intrauterine growth restriction (IUGR) refers to the poor growth of a baby while in the mother's womb during pregnancy.