Final answer:
The best predictor of fetal growth restriction is low birth weight, which is a weight at birth of less than 2.5 kg (5.5 lb). Intrauterine growth restriction (IUGR) may occur due to maternal, fetal, or placental factors, with placental insufficiency being the leading cause.
Step-by-step explanation:
The best predictor of fetal growth restriction is the fetal biometry value of low birth weight. Low birth weight is defined as a weight at birth of less than 2.5 kg (5.5 lb), and it increases the risk of mortality shortly after birth. Fetal growth deficit, known as intrauterine growth restriction (IUGR), may occur due to maternal, fetal, or placental factors, with placental insufficiency being the leading cause of IUGR.