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Intrauterine growth restriction (IUGR)

Maternal pregnancy complications


During pregnancy, fetal growth delays are assessed during obstetrical ultrasound. A fetal weight at or below the 10th percentile of the normal population’s weight at the same gestational age indicates intrauterine growth restriction (IUGR).

Fetuses estimated to be at a very low weight – below the 5th or 3rd percentile – are the most at risk for medical problems.

They should be closely monitored during pregnancy to determine the cause of the growth delay and to assess the consequences.


There are four main causal categories leading to intrauterine growth restriction:

  • Constitutional factors (genetic or familial predispositions).
  • Maternal medical condition (preeclampsia, kidney disease, hypertension and other vascular diseases, etc.).
  • Fetal medical condition (genetic disease, congenital malformation, congenital infections, etc.).
  • Placental function (chronic placental abruption, umbilical cord malformation, abnormal placenta development, etc.).

Tests and procedures

During pregnancy follow-up care, growth restriction is suspected based on medical history, uterine height examination, and first and second trimester obstetric ultrasound findings.

Obstetric ultrasound is the test for identifying restricted growth in a fetus. Depending on the severity of the IUGR and the stage of pregnancy at the time of diagnosis, further investigations may be requested.

These tests can include:

  • A detailed ultrasound for the diagnosis of birth defects
  • Genetic amniocentesis
  • Investigations to identify the presence of congenital infections
  • Investigations to detect maternal diseases such as preeclampsia and other diseases affecting the blood vessels.

Treatment and follow-up care

The goal of pregnancy monitoring in the case of IUGR is to both ensure fetal well-being and to schedule birth at an ideal time. Serial obstetrical ultrasounds are therefore planned to measure fetal growth and monitor fetal health.

Fetal well-being is considered satisfactory if the amount of amniotic fluid is normal, if fetal movements (assessed by a non-stress test or a biophysical profile) are normal, and fetal and placental circulation (evaluated by Doppler ultrasound) is also normal.

Delivery is recommended as soon as the fetus has reached maturity (from the 37th week of pregnancy). Premature delivery, however, is recommended if the index for fetal welfare is not reassuring or if the fetus stops gaining weight.

In severe IUGR cases, hospitalization may be required to allow close monitoring of the fetus. In anticipation of premature delivery, betamethasone therapy is recommended to reduce the risk of complications related to prematurity.


Some lifestyle habits such as quitting smoking, maintaining a healthy weight, and having a balanced diet can make a difference to the normal growth of the fetus.

In pregnant women with risk factors for IUGR, low-dose aspirin is recommended to improve placental function (follow your doctor’s recommendation for dosing). Ideally, chronic diseases such as hypertension, lupus, or diabetes should be well controlled before a woman gets pregnant.

Page by

Chantal Larcher, infirmière clinicienne
Dr Lucie Morin

About this page
Updated on 1/25/2021
Created on 12/19/2017
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