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:

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.

Ultrasound can be used to measure the baby's head and abdomen. The doctor can compare those measurements to growth charts to estimate the baby's weight. Ultrasound can also be used to determine how much amniotic fluid is in the uterus. A low amount of amniotic fluid could indicate IUGR.

Doppler flow. Doppler flow is a technique that uses sound waves to measure the amount and speed of blood flow through the blood vessels. Doctors may use this test to check the flow of blood in the umbilical cord and vessels in the baby's brain.

Weight checks. Doctors routinely check and record the mother's weight at every prenatal checkup. Weight gain in the mother can be used to measure the growth of her unborn baby. If a mother is not gaining weight, it could indicate a growth problem in her baby.

Fetal monitoring. This test involves placing sensitive electrodes on the mother's abdomen. The electrodes are held in place by a lightweight stretchable band and attached to a monitor. The sensors measure the rate and pattern of the baby's heartbeat and display them on a monitor or print them.

Amniocentesis . In this procedure, a needle is placed through the skin of the mother's abdomen and into her uterus to withdraw a small amount of amniotic fluid for testing. Tests may detect infection or some chromosomal abnormalities that could lead to IUGR.

IUGR Treatments

The best way to manage IUGR depends on the severity of growth restriction and how early the problem began in the pregnancy. Generally, the earlier IUGR begins and the more severe it is, the greater the risks to the unborn baby. Careful monitoring of a fetus, using tests such as ultrasound, Doppler flow, and fetal monitoring, may be helpful.


Although it is not possible to reverse IUGR, the following may help slow or minimize the effects.

  • Improving nutrition. Some studies have shown that increasing the mother's nutrition may increase the baby's weight gain and growth in the uterus.
  • Bed rest . Whether in the hospital or at home, bed rest may help improve circulation to the fetus.
  • Delivery. If IUGR puts the baby's health at danger, the doctor may decide to deliver the baby early. If the doctor believes the baby is too weak for the stresses of labor and delivery, or if the baby has problems during labor, a cesarean section (C section) may be safer.

Preventing Intrauterine Growth Restriction

Although IUGR can occur even when a mother is perfectly healthy, there are things mothers can do to reduce the risk of IUGR and increase the odds of a healthy pregnancy and baby.

  • Keep all of your prenatal appointments. Detecting potential problems early allows you treat them early.
  • Be aware of your baby's movements. A baby who doesn't move often or who stops moving may have a problem. If you notice changes in your baby's movement, call your doctor.
  • Check your medications. Sometimes a medication a mother is taking for another health problem can lead to problems with her unborn baby.
  • Eat healthfully. Healthy foods and ample calories help keep your baby well nourished.
  • Get plenty of rest. Rest will help you feel better and it may even help your baby grow. Try to get eight hours of sleep (or more) each night. An hour or two of rest in the afternoon is also good for you.
  • Practice healthy lifestyle habits. If you drink alcohol, take drugs, or smoke, stop for the health of your baby.

WebMD Medical Reference Reviewed by Trina Pagano, MD on October 08, 2014


SOURCES: "Intrauterine Growth Restriction."

Children's Hospital of Pittsburgh of UPMC: "Intrauterine Growth Restriction (IUGR)."

MedlinePlus: "Intrauterine Growth Restriction."

MedlinePlus: "Fetal heart monitoring."

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