Intrauterine Growth Restriction (IUGR)

Definition - What does Intrauterine Growth Restriction (IUGR) mean?

Intrauterine growth restriction (IUGR) refers to poor growth of the unborn baby while inside the mother's uterus during pregnancy. In other words, the baby is small or the weight is below the 10th percentile as would be expected for how far along the mother is in her pregnancy (gestational age). These babies are often referred to as small for gestational age babies. Sadly, IUGR accounts for more than half of the deaths in newborns occurring within the first 28 days following birth. Delayed growth puts the baby at risk for a host of health issues during pregnancy and delivery, as well as after birth.

FertilitySmarts explains Intrauterine Growth Restriction (IUGR)

In the majority of cases, IUGR is secondary to problems that prevent the baby from obtaining sufficient oxygen and nutrients. These problems can be related to the mother, placenta, or the unborn baby itself and include:

Causes in the mother

  • Poor weight
  • Poor nutritional status
  • Reduced hemoglobin (anemia)
  • Smoking
  • Alcohol or drug use
  • Diabetes (developing during pregnancy or present before pregnancy)
  • Celiac disease
  • Cardiovascular disease (including high blood pressure)

Causes pertinent to Placenta (since placenta is the primary route for delivery of oxygen and nutrients to the baby)

  • Pre-eclampsia
  • Placental insufficiency - A condition in which the tissue that supplies oxygen and nutrients to the baby (known as placenta) isn't functioning properly or is attached in the wrong position

Causes in the Unborn Baby

  • Chromosomal abnormalities, such as Down syndrome, or structural birth defects, such as anencephaly (in which portion of the brain is missing)
  • Transmission of infections from the mother, such as toxoplasmosis, rubella, cytomegalovirus, herpes, syphilis, and many others

Babies who experience delayed growth within the mother's uterus are prone to develop following problems:

  • Low birth weight
  • Delivery before 37 weeks of gestation (premature birth)
  • Stillbirth (IUGR is one of the most common factors identified in these babies)
  • Low Apgar scores (a tool used to determine the newborn's physical status and the subsequent need for vigilant medical care in babies with low Apgar scores)
  • Infections (like necrotizing enterocolitis)
  • Hypoglycemia (low blood sugar)
  • Difficulty maintaining body temperature
  • Depleted oxygen levels leading to brain injury
  • Meconium aspiration (baby swallows and inhales their own stools while in the uterus), which causes breathing issues

IUGR is suspected when the height of the upper part of the uterus (fundus) does not coincide with the gestational age on clinical examination. The diagnosis is confirmed by an ultrasound that reveals a fetal weight below the 10th percentile and an amniotic fluid index of less than 5 cm (or less than the 5th percentile).

The treatment of IUGR depends on how far along a woman is in her pregnancy. In women who are at least 34 weeks pregnant, the physician may induce an early delivery. In contrast, women who haven't yet reached 34 weeks into their pregnancy, a "watch and wait" approach is often implemented until any signs of fetal deterioration are apparent, in which case an immediate delivery is performed.

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