Intrauterine Growth Restriction (IUGR) is a condition where the fetus does not develop at the normal rate during pregnancy and is smaller than normal for its gestational age. The condition is caused by the baby not getting enough oxygen and nutrition through the placenta. It is diagnosed by ultrasound and is made when fetal weight is below the 10th percentile for gestational age. IUGR means that your baby is not growing as it should and is not as big as it should be for the number of weeks pregnant you are.
Babies with IUGR have low birth weights and are prone to complications such as breathing and metabolism difficulties. It's important to note that only one third of babies who are small at birth have IUGR. Oftentimes, small babies run in families. Babies who are small at birth, but do not have IUGR are often from parents who are small in stature. These babies are usually healthy.
Babies who have IUGR may be classified into two groups:
- Symmetric or primary IUGR – all the baby's internal organs are small in size. This accounts for 20 to 25 percent of IUGR cases.
- Asymmetric or secondary IUGR – the baby's head and brain are normal in size, but the abdomen is smaller. This is often not apparent until the third trimester.
How Do You Get IUGR?
Smoking, alcohol and drug abuse are direct causes of IUGR. Most IUGR is caused by abnormalities in the placenta that do not allow the baby to receive as much nutrition as it needs. Other factors that increase the risk of your baby having intrauterine growth problems or IUGR include:
- A maternal weight of less than 100 pounds
- Poor nutrition in pregnancy
- Birth defects and chromosomal abnormalities
- Pregnancy-induced hypertension
- Placental abnormalities
- Umbilical cord abnormalities
- Multiple pregnancy (twins or triplets)
- Gestational diabetes in the mother
- Low levels of amniotic fluid or oligohydramnios
How is IUGR Diagnosed?
Your physician will measure the growth of your uterus (this is called fundal height) and your baby during your prenatal visits. If your baby seems small, your provider will double check the dates of your pregnancy to make sure you have the right dates. Gestational age is calculated by using the first day of your last menstrual period and also by early ultrasound calculations. Once your provider is confident in the gestational age, you may undergo the following tests to diagnose IUGR:
- Fundal height measurement to determine if your uterus is smaller than normal
- Ultrasound to calculate your babies weight and measurements
- Doppler ultrasound for more precise calculations
- Fetal monitoring to listen to the baby's heartbeat
- Amniocentesis to possibly determine the cause of IUGR (such as genetic or infection factors) and lung maturity
What Does it Mean for My Baby?
If your baby is diagnosed with IUGR, it means your baby is not getting the nutrition it needs to grow at the normal rate. This means your baby will have a low birth weight and will not be as fully developed at birth. Babies who have low birth weights often have complications such as:
- Hypoxia – lack of oxygen when the baby is born
- Meconium aspiration – swallowing part of the first bowel movement while in the uterus or during birth. This can cause the baby to have problems breathing and infection in the lungs.
- Hypoglycemia – low blood sugar at birth
- Polycythemia – an increased number of red blood cells
- Hyperviscosity – a decrease in blood flow do to having too many red blood cells in the blood
- Development and neurological disabilities
Your baby will most likely require care for several weeks in a neonatal intensive care unit where specialized nurses and physicians can provide advanced treatment and support.
If I am Diagnosed with IUGR, What Happens Next?
Your provider will discuss with you your baby's intrauterine growth, well-being and concerns. If immediate delivery is not needed, you may be asked to carefully monitor your baby's daily movements. Babies who do not move often or stop moving may be sick. Call your doctor if you notice your baby isn't moving as much. You may also be encouraged to rest more and in some cases, bedrest or hospitalization may be required. You will probably see your provider more frequently.
How is it Treated?
If your baby is diagnosed with IUGR, your physician may refer you to a maternal fetal medicine specialist and a hospital that has a neonatal intensive care unit. The treatment will often depend on how far along you are in pregnancy and whether your baby is showing signs of distress or illness. If you are at 34 weeks or more, you may be induced for an early delivery. You may also require a cesarean section (C-section) if your baby is too weak to undergo a vaginal delivery.
If you are less than 34 weeks, you may be monitored more closely until 34 weeks and after. Your provider will carefully monitor your baby's health and the amount of amniotic fluid. If there is concern for your baby's well-being, you may be induced for early delivery.
Your baby will need to remain in the hospital until it can breathe and feed normally and weighs about five pounds. Most babies with low birth weights catch up to normal height around the age of two.