A baby at the center of a bitter legal battle over whether he should have been aborted was born this week with a serious and rare heart defect.

Surrogate McKenna West was about 20 weeks pregnant when the baby she was carrying, Gabriel, was diagnosed with hypoplastic left heart syndrome, a congenital heart defect that requires multiple surgeries and leaves survivors facing lifelong medical care and potentially serious health complications.

West refused the biological parents’ request to terminate the pregnancy, setting off a dispute that has involved courts and officials in three states.

The biological parents had asked West to get an abortion, in accordance with the “abortion on demand” clause of their surrogacy agreement. West refused and traveled to Texas “for protection,” Texas Attorney General Ken Paxton’s office said.

“Every life matters. No woman should be forced to end the life of the baby she is carrying — including me… Baby Gabriel should receive a chance at life,” West told The Post in a statement.

The biological parents, Nausheen Gilkar and Omar Ahmed of California, have taken custody of Gabriel, but West plans to continue fighting for custody of the baby.

So what exactly is hypoplastic left heart syndrome, and what does it mean for Gabriel?

What is hypoplastic left heart syndrome?

Hypoplastic left heart syndrome (HLHS) is a severe birth defect in which the left side of the heart is underdeveloped.

This area of the heart includes the left ventricle, valves and aorta. It is responsible for receiving oxygenated blood from the lungs and getting it delivered around the body.

HLHS affects about one in 3,846 babies born in the US every year.

What are the symptoms and complications of HLHS

A baby born with HLHS may have:

• Difficulty breathing
• Difficulty feeding
• A weak pulse
• Blue, purple or gray lips, skin and nails. The condition is called cyanosis, and happens when happens because there is not enough oxygen in the blood.
• Cold hands and feet
• Lethargy — sleepiness or being less responsive

Without treatment, children born with HLHS may go into shock, and will die from complications including heart failure.

How is hypoplastic left heart syndrome diagnosed?

Babies can be diagnosed before or after birth. Before birth, ultrasounds or echocardiograms (ultrasounds of the heart) can detect the condition.

After birth, they’re diagnosed based on the presenting symptoms, like problems with breathing, feeding and skin color. Doctors may listen to the heart to detect a murmur or “whooshing” sound.

How fatal is HLHS? And what does living with HLHS look like?

HLHS is fatal if left untreated. A baby will only survive for a few weeks at most, according to New York Presbyterian.

With treatment, 72% of children survive to age 5. If they survive to age five, 90% survive to adulthood (age 18). The oldest person to survive HLHS is in their 30s.

Those who survive following the necessary surgeries need lifelong care.

“While these procedures improve circulation, the heart does not function the same way as a typical two-ventricle heart,” the American Heart Association writes. “As a result, some people may develop health problems over time related to blood flow through the heart and lungs. Lifelong follow-up care is important.”

Some children eventually require a heart transplant, even when all these procedures are done. This requires longterm care like immunosuppressants to keep the body from rejecting the new heart.

How is hypoplastic left heart syndrome (HLHS) treated?

In some rare cases, babies can be treated while still in the womb, but this is a “high stakes, highly technical procedure like this takes tremendous coordination between specialties,” said Dr. Sarah Gelehrter, a cardiologist who led this procedure successfully.

Not all HLHS babies are candidates for this. Usually, there are a series of three operations needed in the days and weeks after birth.

First, HLHS babies undergo the Norwood procedure, which allows the right ventricle to pump blood around the body — normally it only pumps to the lungs. This requires making a new path (aorta) from the ventricle to the body, and creates another path (called a shunt) to get blood to the lungs.

At four to six months, a second operation called the Glenn procedure is needed. This allows blood from the upper body (head and arms) to flow to the lungs to get oxygen.

Finally, at age two to three, the Fontan procedure, redirects blood from the lower body to passively flow to the lungs. This allows blood to flow from the heart to the body and return to the lungs to get oxygen, which is most like a “normal” blood flow.