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The heart is the first organ to function in a developing fetus, and it works completely differently than yours does. In this episode of the Healthful Woman Podcast, Dr. Nathan Fox talks with Dr. Jen Lam-Rachlin, a specialist in both maternal-fetal medicine and pediatric cardiology, about fetal echocardiograms: what they look for, why fetal circulation is so unique, and why a prenatal heart diagnosis can change everything about how a family prepares for delivery. Below are some highlights, but we encourage you to listen to the full episode for Dr. Lam-Rachlin’s complete insight.

Why Does a Fetal Heart Work So Differently?

Before birth, a baby doesn’t breathe with its lungs. Oxygen comes through the umbilical cord, and the lungs stay essentially dormant until delivery. To make that possible, the fetal circulatory system relies on several vascular shunts that reroute blood around the lungs entirely. The moment a baby takes that first cry, Dr. Lam-Rachlin explains, the entire circulatory system flips: those shunts begin closing, and blood starts flowing through the lungs for the first time. It’s one of the most dramatic physiological transitions the human body ever undergoes, and it happens in seconds.

What Is a Fetal Echocardiogram, and How Is It Different from the Anatomy Scan?

A standard anatomy scan looks at the heart mainly through a four-chamber view, which catches roughly 30 to 40 percent of heart defects, along with newer additions of the outflow tract views. A fetal echocardiogram goes much further. It’s a dedicated, detailed study of about nine structural views of the heart, along with an assessment of blood flow, checking for turbulence, restriction, or blood moving in the wrong direction. In the hands of a trained pediatric cardiologist or maternal-fetal medicine specialist, this exam picks up more than 90 percent of significant heart defects. Dr. Lam-Rachlin notes that expertise matters here: an untrained eye can miss abnormalities that only show up outside the standard four-chamber view.

How Common Are Congenital Heart Defects, and Who’s at Higher Risk?

Congenital heart defects are the most common birth defect, affecting about 1 percent of live births. Roughly a quarter are critical, meaning they’ll require surgery, while the majority are non-critical. Certain factors raise the odds of a defect above that baseline 1 percent risk: a parent with a history of congenital heart disease, a previous child born with a heart defect, maternal diabetes, conceiving through IVF, or a family history of certain genetic syndromes. Dr. Lam-Rachlin suggests that patients with any of these factors simply ask their provider directly: “Do I have any risk factors for congenital heart defects?”

Why Does Knowing Ahead of Time Matter So Much?

This is where the conversation gets to the heart of it, so to speak. A prenatal diagnosis doesn’t usually change the pregnancy itself or lead families toward termination. What it does is give everyone time. Parents get time to process the diagnosis and ask questions instead of learning about it in an emergency room. The care team gets time to plan delivery at a hospital equipped for pediatric cardiac surgery, and to have a pediatric cardiology team ready the moment the baby is born. As Dr. Lam-Rachlin puts it, the difference between a baby born with an anticipated heart defect and one discovered after birth is “night and day.” Knowing beforehand can also prompt additional genetic testing, since some heart defects travel alongside other syndromes worth identifying early.

Who Actually Manages This Care?

Fetal heart findings typically involve two kinds of specialists working together. The maternal-fetal medicine team handles the structural diagnosis, manages the pregnancy itself, and coordinates any genetic testing. The pediatric cardiology team assesses how severe the defect is, determines whether surgery will be needed, and plans out postnatal treatment. Together, they build a coordinated plan well before the baby arrives.

Listen to the full episode of Fetal Echocardiograms: A Heart to Heart with Dr. Jen Lam-Rachlin on the Healthful Woman Podcast for the complete conversation.

Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!