What Causes Fetal Growth Restriction?

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Fetal growth restriction is when the fetal weight is below the 10th percentile for gestational age which can be determined through an ultrasound test. This can also be called as small-for gestational age (SGA) or intrauterine growth restriction (IUGR).

Different types of Fetal Growth Restriction

There are mainly two different types of fetal growth restriction:

  • Symmetric or primary growth restriction, which can be characterized by the condition when all internal organs are being reduced in size. 20% to 25% of all cases of growth restriction are contributed by symmetric growth restriction.
  • Asymmetric or secondary growth restriction is characterized by the head and brain being normal in size, but the abdomen is smaller. Typically this is not evident until the third trimester.

Risk factors for developing Fetal Growth Restriction

The following conditions may increase the risk for developing fetal growth restriction:

  • Maternal weight of less than 100 pounds
  • Birth defects or chromosomal abnormalities
  • Poor nutrition during pregnancy
  • Pregnancy induced hypertension (PIH)
  • Placental abnormalities
  • Use of drugs, cigarettes, and/or alcohol
  • Umbilical cord abnormalities
  • Multiple pregnancy
  • Low levels of amniotic fluid (oligohydramnios)
  • Gestational diabetes in the mother

How is Fetal Growth Restriction diagnosed?

Accurate pregnancy dating is one of the most important aspects of diagnosing fetal growth restriction. Gestational age can be calculated by using the first day of the last menstrual period (LMP) and by early ultrasound measurements.

Once gestational age has been established, the following methods can be used to diagnose fetal growth restriction:

  • Measurements calculated in an ultrasound are smaller than expected for the gestational age
  • Fundal height that does not coincide with gestational age
  • Abnormal findings discovered by a Doppler ultrasound

Treatment for Fetal Growth Restriction treated

The type of treatment for fetal growth restriction will depend on how far you are in your pregnancy stage.

  • If gestational age is 34 weeks or greater, health care provider may recommend inducing labor early.
  • If gestational age is less than 34 weeks, health care providers continue monitoring fetal well-being and the amount of amniotic fluid until 34 weeks or beyond.
  • If still the risk remains, immediate delivery may be recommended. If delivery is suggested prior to 34 weeks, you may be subjected to amniocentesis to evaluate fetal lung maturity.

Risks to a baby born with Fetal Growth Restriction

Babies born with fetal growth restriction have an increased risk for the following:

  • Cesarean delivery
  • Hypoxia (lack of oxygen when the baby is born)
  • Polycythemia (increased number of red blood cells)
  • Hypoglycemia (low blood sugar)
  • Hyperviscosity (decreased blood flow due to an increased number of red blood cells)
  • Meconium aspiration
  • Motor and neurological disabilities