Intrauterine Growth Restriction (IUGR)

Intrauterine growth restriction (IUGR), sometimes called fetal growth restriction (FGR) or small for gestational age (SGA), is a condition in which an unborn baby’s growth is too slow. IUGR can be caused by problems with the placenta or uterus, as well as underlying maternal or fetal health issues (1). Certain risk factors and physical examination results help doctors suspect IUGR prenatally; it can then be diagnosed by ultrasound (2). Babies with IUGR need to be delivered early because they typically do not tolerate contractions or labor well. A number of injuries and complications are associated with IUGR, including hypoxic-ischemic encephalopathy (HIE), fetal acidosis, and fetal death. IUGR can also lead to permanent disabilities such as cerebral palsy (CP) (1). Because IUGR is such a dangerous condition, failure to diagnose it and recommend an early delivery constitutes medical malpractice.

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Intrauterine Growth Restriction IUGR

Risk factors and causes of intrauterine growth restriction (IUGR)

There are a variety of factors related to the placenta/uterus, maternal health, or fetal health that can lead to IUGR. Causes and risk factors for IUGR include the following (5):

Placental/uterine factors:

  • Placental abruption: This is when the placenta separates, either completely or partially, from the wall of the uterus before the baby is born. Partial placental abruption can cause IUGR.
  • Infection of the tissues that surround the growing baby (see chorioamnionitis).
  • Decreased blood and nutrient flow in the uterus and/or placenta.

Maternal factors:

  • Maternal high blood pressure/preeclampsia
  • Diabetes
  • Maternal heart issues
  • Maternal kidney diseases
  • Maternal infection
  • Malnutrition
  • Anemia
  • Small mother and parents
  • Poor weight gain in pregnancy
  • Mother weighs less than 100 lbs at the start of pregnancy
  • Use of cigarettes during pregnancy

Fetal factors:

Please note that this is not a complete list. For more risk factors and causes, please click here.

Detecting and diagnosing intrauterine growth restriction (IUGR)

Historically, IUGR has been diagnosed using both ultrasonographic examinations and fundal height measurements. However, fundal height measurements often fail to accurately and reliably diagnose IUGR. The American College of Obstetricians and Gynecologists (ACOG) explains that “ultrasonography remains the best method for evaluating the growth-restricted fetus” (6). If IUGR is suspected (or risk factors are present), ultrasounds should be performed regularly throughout the pregnancy. Ultrasounds can be used to estimate a baby’s growth (generally, an estimated fetal weight below the 10th percentile is indicative of IUGR, although there are some exceptions to this rule) (1). Ultrasound may also indicate a low amniotic fluid volume (oligohydramnios) or problems with blood flow, both of which may be apparent in pregnancies involving IUGR (7, 8).

Fundal Height | Measuring Fetal Growth and Development

Management of IUGR

Upon receiving an IUGR diagnosis, the mother may be referred to maternal-fetal specialists. These are physicians with specialized training and expertise in the management of IUGR. They should very carefully monitor the baby’s health throughout the remainder of the pregnancy.

There are a variety of tests that should be done to  assess the wellbeing of a baby with IUGR. These include the following:

  • Weight checks. Medical staff should check the mother’s weight at each prenatal visit. If a mother is not gaining weight, this should prompt doctors to check for a fetal growth problem (9).
  • Non-stress tests (NSTs). The nonstress test is a simple test performed to ensure that unborn babies’ hearts react appropriately to different forms of movement and stimulation.
  • Amniotic fluid index (AFI). An ultrasound can obtain a measurement called the amniotic fluid index, or AFI. This can reveal if there is oligohydramnios (abnormally low amniotic fluid) or polyhydramnios (abnormally high amniotic fluid).
  • Biophysical profiles (BPP). The biophysical profile (BPP) predicts the presence or absence of fetal asphyxia (severe hypoxia) as well as the risk of death during the antenatal period (the short period after birth).
  • Doppler velocimetry. Doppler velocimetry is a prenatal test that gives physicians information about uteroplacental blood flow and the baby’s responses to physiological challenges.

If the findings of these studies are non-reassuring, prompt delivery needs to be considered.  

Timing of delivery for IUGR during pregnancy

Because of the extreme risk associated with moderate to severe fetal IUGR, many physicians will recommend early delivery.

Treatment for IUGR, based on gestational age, includes the following:

  • If the pregnancy is 34+ weeks along, physicians may recommend an early delivery (often via c-section).
  • If the pregnancy is less than 34 weeks along, physicians will continue to carefully monitor the health of the fetus and the amount of amniotic fluid. If the believe the baby is in serious danger, they will recommend an early delivery. They must weigh the risks of prematurity with the risks of IUGR-associated complications. When delivery is suggested prior to 34 weeks, the physician may recommend an amniocentesis to help evaluate fetal lung maturity. This can help determine how likely a baby is to suffer from respiratory distress syndrome or other issues. If the lungs are underdeveloped, physicians may also recommend certain treatments that can help accelerate development in utero or improve breathing once the baby is born (10).
  • In any case, delivery must occur before 40 weeks gestation.  

Dangers of IUGR

Small babies do not tolerate contractions or labor well.  As such, they can be deprived of oxygen and may experience a number of complications. These include the following:

Intrauterine growth restriction (IUGR) and medical malpractice

When risk factors for IUGR are present or when IUGR is confirmed during pregnancy, it is essential that the physician properly assess and monitor the growth of the baby. In certain instances, it may be necessary to plan to deliver the baby early. Failure to treat the underlying cause of the IUGR and to properly monitor and plan for the birth can result in serious and permanent injuries. If this happens, it constitutes medical malpractice.

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Video: Intrauterine Growth Restriction and Birth Injury


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  2. (n.d.). Retrieved August 23, 2018, from
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  5. Default – Stanford Children’s Health. (n.d.). Retrieved August 23, 2018, from
  6. American College of Obstetricians and Gynecologists. (2013). ACOG Practice bulletin no. 134: fetal growth restriction. Obstetrics and gynecology, 121(5), 1122.
  7. Moh, W., Graham, J. M., Wadhawan, I., & Sanchez-Lara, P. A. (2012). Extrinsic factors influencing fetal deformations and intrauterine growth restriction. Journal of pregnancy, 2012.
  8. Gutaj, P., & Wender-Ozegowska, E. (2016). Diagnosis and management of IUGR in pregnancy complicated by type 1 diabetes mellitus. Current diabetes reports, 16(5), 39.
  9. Strauss, R. S., & Dietz, W. H. (1999). Low maternal weight gain in the second or third trimester increases the risk for intrauterine growth retardation. The journal of nutrition, 129(5), 988-993.
  10. Intrauterine growth restriction | Small for Gestational Age. (2017, February 22). Retrieved August 23, 2018, from