In brief — the direct answer
Congenital heart defects range from small structural differences to complex conditions requiring urgent neonatal care. Detailed assessment aims to define the anatomy, look for associated findings and discuss what remains uncertain. Prenatal diagnosis can support appropriate birth location and early treatment planning; outcome and benefit vary with the specific condition.
What is Congenital Heart Defects (CHD)?
CHD occurs when the baby's heart does not form correctly during the first trimester. The defect can affect the heart walls (septa), the valves, or the major arteries leaving the heart.
Common types of CHD diagnosed prenatally include:
- Ventricular Septal Defect (VSD): A hole between the lower chambers of the heart.
- Tetralogy of Fallot (ToF): A combination of four related heart defects.
- Transposition of the Great Arteries (TGA): Where the two main arteries leaving the heart are swapped.
- Hypoplastic Left Heart Syndrome (HLHS): A severe condition where the left side of the heart is underdeveloped.
- Atrioventricular Septal Defect (AVSD): Often associated with Trisomy 21 (Down Syndrome).
Who is at risk?
In about 80% of cases, CHD occurs in pregnancies with no known risk factors. However, the risk is higher if:
- Maternal Health: The mother has pre-existing diabetes or certain autoimmune conditions.
- Genetics: There is a family history of CHD or if a chromosomal condition like Down syndrome is suspected.
- Medications: Exposure to certain medications during the first trimester.
- IVF: Pregnancies conceived via IVF have a slightly higher reported incidence of minor heart defects.
Because of the 'low risk' nature of most cases, a detailed 20-week anomaly scan is the primary screening tool for all women.
How we diagnose it
If a standard anomaly scan raises any suspicion, we perform a Fetal Echocardiogram.
This is a highly specialized ultrasound focused entirely on the fetal heart. Our cardiology leads, like Dr. Gareth Waring, examine the 'four chambers,' the 'outflow tracts,' the connection of the veins, and the heart's rhythm and function using advanced Doppler techniques. Prenatal diagnosis allows us to assess whether the condition will be stable throughout pregnancy or if it might progress (e.g., a valve becoming tighter).
What does management involve?
During pregnancy, management focuses on monitoring the baby's growth and heart function. Most babies with CHD are stable in the womb because the mother's placenta provides the oxygen.
- Multidisciplinary Team: We arrange consultations with specialized Pediatric Cardiologists and Cardiac Surgeons at our partner hospitals.
- Delivery Planning: For 'critical' heart defects, we ensure the birth takes place in a tertiary hospital with immediate access to a Level III NICU and pediatric cardiology support.
- In-Utero Treatment: In very rare cases (like severe aortic stenosis), fetal cardiac intervention (balloon dilation in the womb) might be discussed, though this is only available in a few centers worldwide.
What are the outcomes?
The outlook for children with CHD has improved remarkably over the last 30 years.
- Simple Defects: Many minor holes (VSDs) close on their own after birth or require one simple procedure with a normal life expectancy.
- Complex Defects: Even babies built with 'half a heart' (like HLHS) can now undergo successful series of surgeries to reach adulthood.
- Prenatal Advantage: Studies consistently show that babies diagnosed with complex CHD before birth have a lower risk of brain injury and better surgical outcomes because they are not 'born in crisis'—they receive immediate specialized care.
When to see a subspecialist
If your sonographer mentions difficulty seeing the heart or says 'something doesn't look quite right with the four-chamber view,' an immediate referral for a Fetal Echocardiogram at the MFM Unit is required.
A delay in diagnosis can be the difference between a planned, safe delivery and an emergency postnatal stabilization. We provide comprehensive counseling, linking you directly with the specialists who will care for your baby after they are born.