What to Know About Intrauterine Growth Restriction (IUGR) in the Third Trimester

Posted On: May 20, 2020 By CIW

Sometimes, your baby doesn’t develop in the womb at the rate that it should. This is called intrauterine growth restriction (IUGR), and it can come with some risks to your baby both during and after pregnancy, meaning it’s important to take the right steps with the help of your maternal fetal medicine specialist. Here’s what to know about it and how your maternal fetal medicine specialist can help. 

What is Intrauterine Growth Restriction? 

Intrauterine growth restriction (IUGR) is a condition where an unborn baby is smaller than normal because of a slower growth rate in the womb. This can come with some risks including a low birth weight, decreased oxygen levels, greater risk during delivery, greater risk of infections, low blood sugar, and problems breathing or maintaining body temperature. Sometimes, IUGR can lead to long-term growth problems after birth. 

What Makes IUGR Different from SGA (Small for Gestational Age)? 

When intrauterine growth restriction (IUGR) is suspected during the third trimester, the majority of IUGR fetuses will either be constitutionally small, or have growth restriction due to placental insufficiency. Other less common causes are aneuploidy, other genetic disorders, fetal malformations, and fetal infection. However, in most cases, the typical question is whether the fetus is constitutionally small or growth-restricted from placental insufficiency. 

How Is IUGR Diagnosed? 

To differentiate a constitutionally small fetus from a growth-restricted fetus, we use several tests. The simplest approach is analyzing the parents’ size and ethnicity. Smaller parents are more likely to have smaller babies. Additionally, the morphology of the fetus may differentiate growth restriction (small abdomen and normal head) from a constitutionally small fetus (similar sized abdomen and head, small long bones). 

Other signs of placental insufficiency, such as pre-eclampsia, oligohydramnios, and an abnormal biophysical profile or non-stress testing would also indicate that a small fetus is more likely to be growth restricted, as these tests indicate placental insufficiency. Finally, the two most valuable tests are interval growth over time and umbilical artery Doppler velocitometry. 

A fetus that is small but growing is less likely to be growth restricted, and is more likely to benefit from remaining in utero, especially in light of other reassuring testing. In the setting of reassuring testing, it is not recommended to deliver a preterm small fetus with adequate interval growth. 

Doppler velocitometry is helpful in assessing small fetuses, and has been associated with a decreased mortality in small fetuses. Normal umbilical artery Doppler findings are very reassuring and imply a normally functioning placenta, making growth restriction from placental insufficiency less likely or less severe. While Doppler assessment would likely be normal in a fetus that is small due to a genetic abnormality or early infection, in such cases, early delivery would be very unlikely to improve outcomes, and iatrogenic prematurity would likely worsen outcomes for such fetuses. 

How Can I Prevent IUGR? 

Intrauterine growth restriction can still occur in cases where you’re healthy, so it’s important to take some steps to prevent it from developing. This includes: 

  • Discussing your medications with your maternal fetal medicine specialist. Some medications that you take for another health condition can cause complications during pregnancy. 
  • Eating healthy foods in the right amounts. It’s extremely important to ensure your baby has the nutrients it needs during pregnancy. 
  • Making sure you’re getting enough sleep. You should aim for at least eight hours of sleep at night with more rest during the day. 
  • Keeping track of your baby’s movements. If your baby doesn’t move often or you notice a change, you should discuss your observations with your maternal fetal medicine specialist. 
  • Avoiding things like alcohol or smoking. These can cause a host of complications during pregnancy. 
  • Keeping up on your appointments with your maternal fetal medicine specialist. If any concerns about your baby’s size and development are caught early, they can be treated ahead of time. 

Schedule an Appointment 

The best way to prevent and diagnose IUGR is by meeting with our award-winning team of maternal fetal medicine specialists. To get started, we invite you to contact our New York City office by calling or filling out our online form. 


Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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