Intrauterine growth restriction (IUGR) refers to a condition in which an unborn baby is smaller than it should be because it is not growing at a normal rate inside the womb.

Delayed growth puts the baby at risk of certain health problems during pregnancy, delivery, and after birth. They include:

• Low birth weight

• Difficulty handling the stresses of vaginal delivery

• Decreased oxygen levels

• Hypoglycemia (low blood sugar)

• Low resistance to infection

• Low Apgar scores (a test given immediately after birth to evaluate the newborn's physical condition and determine need for special medical care)

• Meconium aspiration (inhalation of stools passed while in the uterus), which can lead to breathing problems

• Trouble maintaining body temperature

• Abnormally high red blood cell count

In the most severe cases, IUGR can lead to stillbirth. It can also cause long-term growth problems.

Causes of Intrauterine Growth Restriction

IUGR has many possible causes. A common cause is a problem with the placenta. The placenta is the tissue that joins the mother and fetus, carrying oxygen and nutrients to the baby and permitting the release of waste products from the baby.

The condition can also occur as the result of certain health problems in the mother, such as:

• Advanced diabetes

• High blood pressure or heart disease

• Infections such as rubella, cytomegalovirus, toxoplasmosis, and syphilis

• Kidney disease or lung disease

• Malnutrition or anemia

• Sickle cell anemia

• Smoking, drinking alcohol, or abusing drugs

Other possible fetal causes include chromosomal defects in the baby or multiple gestation (twins, triplets, or more).