Intrauterine Growth Restriction (IUGR)

Symptoms

• IUGR usually doesn't cause symptoms for the pregnant person. The main sign is often a fundal height measurement (the distance from your pubic bone to the top of your uterus) that is smaller than expected for your stage of pregnancy.
• A perceived decrease in your baby's movements can sometimes be a sign, but this is often a late indicator.
• Significantly decreased or absent fetal movement requires immediate medical attention.

Causes & Risk Factors

• Problems with the placenta (uteroplacental insufficiency), which is the most common cause. The placenta may not be able to deliver enough nutrients and oxygen to the baby. This can be linked to maternal conditions like high blood pressure or pre-eclampsia.
• Genetic or chromosomal problems with the baby itself, such as Trisomy 13 or 18, which can limit growth.
• Infections passed from the mother to the baby during pregnancy, such as cytomegalovirus or toxoplasmosis.
• Chronic health conditions in the mother, like kidney disease or autoimmune diseases, can affect placental function or nutrient supply.
• Exposure to certain substances during pregnancy, including smoking, alcohol, illicit drugs, or some medications.
• In some cases, a specific cause cannot be identified, and the reason for the growth restriction remains unknown.
• Previous pregnancy with FGR
• Chronic health conditions such as high blood pressure, diabetes before pregnancy, kidney disease, or autoimmune diseases (like Systemic Lupus Erythematosus, Antiphospholipid Syndrome)
• Pregnancy-related conditions like pre-eclampsia or gestational hypertension
• Smoking, alcohol, or illicit drug use
• Poor nutrition or low weight before pregnancy
• Being over 35-40 years old
• Short time between pregnancies
• Carrying multiples (twins, triplets)
• Chromosomal abnormalities (e.g., Trisomy 13, 18, 21)
• Congenital structural problems (e.g., cardiac defects, gastroschisis)
• Congenital infections (e.g., cytomegalovirus, toxoplasmosis, syphilis, rubella)
• Problems with the placenta (e.g., chronic placental abruption, placenta previa)
• Abnormal umbilical cord insertion (e.g., velamentous insertion)
• Uterine abnormalities (e.g., septate uterus)

Diagnosis

• Your doctor will review your medical and pregnancy history, including any risk factors.
• Regular measurement of your fundal height (from your pubic bone to the top of your uterus) during prenatal appointments. If this measurement is consistently smaller than expected or shows slow growth, further evaluation is needed.
• An ultrasound is the main tool for diagnosis. It involves:
• Fetal Biometry: Measuring your baby's head, abdomen, and thigh bone to estimate their weight.
• Amniotic Fluid Volume: Checking the amount of fluid around your baby, as low fluid (oligohydramnios) can be associated with IUGR.
• Doppler Velocimetry: This special ultrasound assesses blood flow in key vessels, such as the umbilical artery (to check placental function), the middle cerebral artery (to see if the baby is redirecting blood flow to the brain), and sometimes the ductus venosus (for severe cases). Abnormal blood flow patterns can indicate problems.
• IUGR is most commonly diagnosed when your baby's estimated weight is below the 10th percentile for their gestational age. Some guidelines also consider Doppler findings or a weight below the 3rd percentile to confirm a pathological growth restriction.
• It's important to distinguish IUGR from a baby who is naturally small but healthy (constitutionally small for gestational age) or from cases where the due date might be incorrect.
• Your doctor will recommend serial fundal height measurements. If abnormal, an ultrasound for estimated fetal weight (EFW) will be performed. If IUGR is diagnosed, serial ultrasounds for growth and Doppler assessment are indicated.

Treatment Options

• There is no specific medication to reverse IUGR once it has developed. Management focuses on monitoring your baby closely, optimizing your health, and deciding the best time for delivery.
• Stopping smoking, avoiding alcohol and illicit drugs, and maintaining a balanced diet are important. Bed rest is generally not recommended as it has not been shown to help and may increase other risks.
• Low-dose aspirin may be used before IUGR develops in women at high risk of pre-eclampsia, but it's not a treatment for established IUGR. Antenatal corticosteroids (like betamethasone) may be given if early delivery is expected, to help mature your baby's lungs. Magnesium sulfate may be given for neuroprotection if delivery is anticipated before 32 weeks.
• Close monitoring is key and may include:
• Fetal Growth Monitoring: Regular ultrasounds (every 2-4 weeks) to track your baby's growth.
• Fetal Well-being Assessment: Frequent Doppler ultrasounds (often weekly or twice weekly) to check blood flow, and non-stress tests (NSTs) or biophysical profiles (BPPs) to assess your baby's health.
• Fetal Movement Counting: You may be advised to monitor your baby's movements daily.
• The timing of delivery is a critical decision, balancing the risks of prematurity against the risks of continuing the pregnancy. Delivery may be recommended earlier if there are signs of worsening fetal compromise. Vaginal delivery may be possible, but a cesarean section might be considered more readily due to the increased risk of your baby not tolerating labor well.
• If IUGR is diagnosed, you may be referred to a Maternal-Fetal Medicine (MFM) specialist. Delivery should ideally take place at a hospital with a Neonatal Intensive Care Unit (NICU) to care for your baby.

Frequently Asked Questions