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Intrauterine Growth Restriction (IUGR)

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).

IUGR Symptoms

The main symptom of IUGR is a small for gestational age baby. Specifically, the baby's estimated weight is below the 10th percentile -- or less than that of 90% of babies of the same gestational age.

Depending on the cause of IUGR, the baby may be small all over or look malnourished. They may be thin and pale and have loose, dry skin. The umbilical cord is often thin and dull instead of thick and shiny. 

Not all babies that are born small have IUGR.

IUGR Diagnosis

Doctors have many ways to estimate the size of babies during pregnancy. One of the simplest and most common is measuring the distance from the mother's fundus (the top of the uterus) to the pubic bone. After the 20th week of pregnancy, the measure in centimeters usually corresponds with the number of weeks of pregnancy. A lower than expected measurement may indicate the baby is not growing as it should.

Other procedures to diagnose IUGR and assess the baby's health include the following:

Ultrasound. The main test for checking a baby's growth in the uterus, ultrasound involves using sound waves to create pictures of the baby. The ultrasound exam lets the doctor see the baby in the uterus with an instrument that is moved over the mother's abdomen.

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