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Fetal Growth Restriction

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Fetal Growth Restriction

Overview

Fetal Growth Restriction (FGR), also known as Intrauterine Growth Restriction (IUGR), occurs when a fetus does not grow at a normal rate inside the womb.

Definition

IUGR: When the birth weight of newborn infant is below the 10th percentile for a given gestational age

Low birth weight: (<2500 grams)

Small for Gestational Age (SGA) indicates that a fetus or neonate is below a defined reference range of weight for a gestational age.

Etiology of IUGR

Maternal Factors

  • Behavioral:

    • Poor nutritional intake
    • Cigarette smoking
    • Drug abuse

  • Medical:

    • Hereditary thrombophilia
    • Early cardiovascular disease
    • Hypertension
    • Diabetes
    • Obesity (associated with leptin resistance)
    • Alcoholism
    • Cyanotic heart disease
    • Pulmonary insufficiency
    • Antiphospholipid syndrome

Other Factors

  • Teratogen Exposure: Exposure to harmful substances during pregnancy.

  • Extreme Maternal Age: Being at the extremes of reproductive age.

  • Fetal Factors:

    • Intrauterine infection (listeriosis and TORCH)
    • Congenital anomalies

  • Placental Factors:

    • Poor implantation
    • Placenta previa
    • Umbilical cord abnormality (Mcikeymouse, 2 artery, 1 vein normally, single down usually)

Types of IUGR

Symmetric vs. Asymmetric IUGR

  • Symmetric (or Primary) IUGR: Each fetal body part is tiny in size, accounting for up to 30% of all IUGR patients.
  • Asymmetric (or Secondary) IUGR: Only the fetus’s abdomen measures small, with the head and brain having proper sizes, representing up to 80% of all IUGR cases.

Classification Based on Gestational Age

  • Early FGR: Less than 32 weeks.
  • Late-Onset FGR: Diagnosed at or after 32 weeks.

Diagnosis

  • Serial uterine fundal height measurements: Fundal height lags more than 3 cm behind expectations.
  • Ultrasound:
    • Fetal biometry: biparietal diameter (BPD), head circumference, abdominal circumference, femoral length, calculated fetal weight.
    • Amniotic fluid volume. (index 5-25; divide abdomen in four, no fetal or cord part, measure. vertical from four areas, take ratio of total of >25 poly <5 oligio //// - >8 poly <2 olig pockets of air)
    • Umbilical artery Doppler: low, absent, or reversal of diastolic flow.

Ultrasound Images of a Fetal Head

Umbilical Artery Doppler Ultrasound

FGr at term deliver, before 37wk, assess doppler if abnormal deliver

Progression of Umbilical Artery Doppler Changes

  • Normal pregnancy
  • Reduced end diastolic velocity
  • Absent end diastolic velocity
  • Reversed end diastolic velocity (Dexamethasone + Deliver now)

Key Diagnostic Parameters

  • Abdominal circumference is the single most effective parameter for predicting fetal weight. Z
  • Maternal lab tests: serology, amniocentesis.

Management

Pre-Pregnancy

  • Stop smoking and alcohol consumption.
  • Improve nutrition.
  • Aspirin 81mg/day. z

Antepartum

  • Stop smoking.
  • Improve nutrition.
  • Work leave. z
  • Teach the patient about fetal kick count. z
  • Hospitalization. (if absent fetal kick or reduced, if doppler is absent must be done twice week in such patient, medically unstsable, severe IUGR, if patient lives far away-;, biophysical profile is done)

Monitoring

  • Twice-weekly nonstress test (NST) and biophysical profile (U/S, fetal movement, breathing, amniotic fluid, gross movement, ). - modified (Amniotic fluid index + CTG) - normal 8-10 - 4-6 suspicious, <4 abnormal CC?
  • Umbilical artery Doppler weekly.

Labor and Delivery

Treatment of a fetus with suspected IUGR hinges on the clinical context, especially gestational age.

  • Gestational age < 34 weeks – administer a course of antenatal corticosteroids to promote lung maturation.

  • IUGR itself is not a contraindication to induction of labor; however, maintain a low threshold for proceeding to caesarean section if maternal or fetal status warrants.

Complications

  • Increased chance of C-section and early birth.
  • Breathing and feeding issues during birth.
  • Hypoxia.
  • Hypoglycemia.
  • Having trouble regulating body temperature.
  • Meconium aspiration.
  • Polycythemia.
  • Infection.
  • NICU admission.

Clinical Scenarios Z

Case 1

-D 2-3 weeks difference in size estimatino, doppler twice weekly or once

Case 2

-A basic = fetal biomentry

biometry initially, biophysical detailed.

Graph View

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