Final answer:
Symmetrical intrauterine growth restriction (IUGR) is most likely a result of placental insufficiency, maternal undernutrition, or pituitary dwarfism.
Step-by-step explanation:
Symmetrical intrauterine growth restriction (IUGR) is most likely a result of placental insufficiency. Placental insufficiency is a problem with the placenta that causes inadequate transfer of oxygen and nutrients to the fetus, leading to slow growth. This condition can be caused by maternal, fetal, or placental factors.
Maternal undernutrition and low birth weight can also contribute to symmetrical IUGR. Babies with low birth weight are more susceptible to disease and developmental delays. Additionally, pituitary dwarfism can result in symmetrical growth restriction due to abnormally low levels of growth hormone (GH).