Fetal growth restriction

Fetal Growth Restriction

Fetal Growth Restriction (FGR), also known as Intrauterine Growth Restriction (IUGR), is a condition in which a fetus is unable to achieve its genetically determined potential size. It is a significant concern in obstetrics due to its association with increased perinatal morbidity and mortality.

Definition

Fetal Growth Restriction is typically defined as a fetal weight below the 10th percentile for gestational age as determined by ultrasound measurements. However, it is important to distinguish between constitutionally small but healthy fetuses and those that are pathologically small due to FGR.

Etiology

FGR can result from a variety of maternal, fetal, and placental factors:

Maternal Factors

• Hypertension
• Pre-eclampsia
• Malnutrition
• Substance abuse (e.g., smoking, alcohol, drugs)
• Chronic diseases (e.g., diabetes, renal disease)

Fetal Factors

• Chromosomal abnormalities (e.g., Down syndrome)
• Congenital infections (e.g., cytomegalovirus, toxoplasmosis)
• Multiple gestations (e.g., twins, triplets)

Placental Factors

• Placental insufficiency
• Placental abruption
• Abnormal placentation (e.g., placenta previa)

Diagnosis

The diagnosis of FGR is primarily based on ultrasound assessment. Key ultrasound findings include:

• Estimated fetal weight below the 10th percentile
• Abnormal Doppler ultrasound studies, particularly of the umbilical artery
• Oligohydramnios (reduced amniotic fluid volume)

Management

Management of FGR involves close monitoring and timely delivery to minimize risks to the fetus. Strategies include:

• Regular ultrasound assessments to monitor fetal growth and well-being
• Doppler studies to assess blood flow in the umbilical artery and other vessels
• Antenatal corticosteroids to enhance fetal lung maturity if early delivery is anticipated
• Timing of delivery based on fetal condition and gestational age

Prognosis

The prognosis for fetuses with FGR depends on the underlying cause, severity, and gestational age at diagnosis. Early detection and appropriate management can improve outcomes, but FGR is associated with increased risks of:

• Preterm birth
• Low birth weight
• Neonatal complications (e.g., respiratory distress syndrome, hypoglycemia)
• Long-term developmental issues

Prevention

Preventive measures focus on optimizing maternal health and addressing modifiable risk factors:

• Adequate prenatal care
• Nutritional support
• Smoking cessation programs
• Management of chronic maternal conditions

See Also

• Pre-eclampsia
• Ultrasound
• Neonatal care

References

• American College of Obstetricians and Gynecologists. (2020). "Fetal Growth Restriction: ACOG Practice Bulletin, Number 227."
• Royal College of Obstetricians and Gynaecologists. (2014). "The Investigation and Management of the Small-for-Gestational-Age Fetus."