Heart of the Matter

— a Glimpse of Wonder entry™ (Part 8 of 9) —

The human heart starts beating just three weeks after conception. Before the brain forms. Before the limbs take shape. Before the mother even knows she’s pregnant… a tiny pulse begins.

But what begins as a flicker becomes a thunderous transformation.

Inside the womb, the baby’s heart doesn’t function like yours does. Not yet. It’s running a temporary, alternate design—tailored for a world where lungs don’t breathe air. Blood must bypass the lungs, which are still developing and filled with fluid. So Jehovah designed a clever workaround: three special shunts, or detours, that reroute blood through the fetal body.

The most famous is the foramen ovale—a small flap-like opening between the right and left atria of the heart. It allows oxygen-rich blood from the placenta to flow directly from one side of the heart to the other, skipping the lungs entirely.

Then there’s the ductus arteriosus, a temporary vessel that connects the pulmonary artery (which normally sends blood to the lungs) directly to the aorta (which sends it to the body). This helps ensure that most blood flows through the body without detouring to the non-functioning lungs.

And finally, the ductus venosus channels oxygen-rich blood from the umbilical vein directly to the heart, bypassing the liver’s filtration system, which isn’t fully online yet. All of this means blood is distributed precisely—prioritizing oxygen to the brain and heart, even in the womb.

But here’s what’s astonishing: this isn’t just a patchwork system. It’s a temporary operating mode. These detours are designed to shut down. And they do—within moments of birth.

The moment the baby takes its first breath, pressure in the lungs drops. Blood flows in. Oxygen levels rise. These changes trigger an internal switch. The foramen ovale begins to close. The ductus arteriosus constricts and seals. The ductus venosus fades from use. All three fetal bypasses are phased out, often within hours or days. Eventually, they leave only tiny remnants—evidence that this backup system once ran the show.

If any one of these fails to close, serious problems can occur. And yet… in most births, they do. Perfectly. Automatically. No surgery. No technician. No reboot.

Who wrote that code?

Psalm 104:24 says, “How many your works are, O Jehovah! You have made all of them in wisdom.” The human heart—especially in its fetal form—is one of the most intricate displays of that wisdom. It’s not just a pump. It’s a system that anticipates change. That runs in one mode before birth and flips to another at just the right time.

What kind of mind prepares a heart to beat one way… and then change completely, the moment it meets the world?

Jehovah didn’t just give us life. He gave us the ability to transition into it.