Fetal Growth Restriction (FGR)

It is vital to distinguish between a baby that is Small for Gestational Age (SGA) and one that has FGR.

• SGA: A baby that is small (below the 10th centile) but healthy. They are just 'small by nature' (often because the parents are small).
• FGR: A baby that is small and showing signs of distress or 'starvation.' Their growth velocity has slowed, their amniotic fluid may be low, or their Doppler flow studies are abnormal.

We categorize FGR into two types:

1. Early-onset (before 32 weeks): Typically more severe, often associated with maternal pre-eclampsia, and requires very delicate management to balance prematurity against the risk of remaining in the womb.
2. Late-onset (after 32 weeks): More common and harder to detect. The baby may still be 'mid-sized' (e.g., 20th centile) but has dropped from a higher centile, which is a significant warning sign.

Factors that increase the risk of FGR include:

• Maternal Conditions: High blood pressure (Hypertension), pre-eclampsia, kidney disease, or autoimmune disorders.
• Lifestyle: Smoking or poor nutrition can significantly impact placental development.
• Placental Issues: Abnormal development of the placental blood vessels (often caught early by Uterine Artery Doppler screening).
• Infections or Genetics: In some cases, FGR can be caused by a fetal infection (like CMV) or a chromosomal variation.

At the MFM Unit, we use a 'multi-modal' approach to diagnose FGR:

1. Growth Velocity: We look for a 'flattening' of the growth curve over 2-3 weeks.
2. The 3rd Centile Rule: Any baby whose weight is below the 3rd centile is automatically managed as FGR, even if Dopplers are normal.
3. Cerebroplacental Ratio (CPR): A calculation comparing the blood flow in the brain to the blood flow in the umbilical cord. A low CPR suggests 'Brain-Sparing,' where the baby is diverting blood to the brain to survive a poor placental supply.
4. Ductus Venosus (DV): This is the 'final warning' vessel. Abnormalities in the DV Doppler indicate that the baby's heart is starting to struggle, which often triggers immediate delivery in early-onset FGR.

There is no 'medicine' that makes the placenta grow better. Management is entirely about Timing of Delivery.

• Surveillance: Depending on the severity, we may monitor the baby with Doppler and CTG (heart rate monitoring) daily, twice-weekly, or weekly.
• Corticosteroids: Given to mature the baby's lungs if delivery is likely before 34-36 weeks.
• Magnesium Sulfate: Used to protect the baby's brain if delivered very early (before 32 weeks).
• Delivery: We aim for a vaginal delivery in many cases, but if the Dopplers are very abnormal (Absent or Reversed flow), a Caesarean section is often safer as these babies may not tolerate the stress of labor.

While FGR increases the risk of NICU admission and potential developmental delays, the long-term outlook for most babies is excellent when managed by subspecialists.

Accurate diagnosis prevents 'unnecessary' early deliveries for babies who are just naturally small, while ensuring that truly restricted babies are delivered before they suffer harm. Survivors of FGR sometimes face a higher risk of metabolic issues (like diabetes or high blood pressure) in adulthood, which highlights the importance of good pediatric care following birth.

If you have been told your 'baby has stopped growing' or that your 'umbilical artery flow is up,' you should speak to an MFM consultant immediately.

Deciding when to deliver a small baby is one of the most critical decisions in obstetrics. Our consultants, including Dr. Leanne Bricker, utilize the latest evidence from major international trials (like TRUFFLE) to ensure your baby is delivered at the 'Goldilocks' moment—not too early (avoiding prematurity risks) and not too late (avoiding placental failure risks).