Aug. 9, 1963: President John F. Kennedy mounts the steps of Otis Air Force Base Hospital in Massachusetts to tell his wife Jacqueline that their baby son Patrick had died two days after he was born. (Associated Press)

Steven Levingston is The Washington Post’s nonfiction book editor. This essay is adapted from the e-book “The Kennedy Baby: The Loss That Transformed JFK.”

On Aug. 7, 1963, the news from Otis Air Force Base on Cape Cod, Mass., flashed around the world: President John F. Kennedy and his wife, Jacqueline, had welcomed a third child. The boy arrived 51 / 2 weeks early and weighed just 4 pounds, 101 / 2 ounces. Immediately he began a struggle for life.

The Kennedy newborn suffered from hyaline membrane disease, a lung ailment that at the time was the No. 1 killer of babies born before full term. When the president looked in on him, he saw his son’s chest heaving to draw air, and he ordered a Secret Service agent to track down a chaplain — the baby needed to be baptized at once. Twenty minutes later, the child was christened Patrick Bouvier Kennedy, after the president’s grandfather and Jackie’s father.

Treatment options for Patrick were minimal — mostly just a heat-controlled incubator and lots of attention. The critical period was the first 48 hours of life: If the baby could struggle through that delicate time, the odds were better that he’d survive, though they were still only 40 to 50 percent. Had Patrick been born in 2013, he would have had the benefit of ventilators and neonatal intensive-care units, and a 95 percent likelihood of surviving.

To give him every chance, the newborn was rushed from Cape Cod to one of the finest hospitals in the world: Children’s Medical Center in Boston. A vigil began, and crowds waited for the president outside the hospital. “They greeted him ghoulishly with applause and cheers,” journalist Mary McGrory wrote. “If they honored his anguish, they gave no sign.”

As the hours ticked by, Americans huddled by their radios, listening for updates. To many, the mystique of the Kennedys meant that luck was on Patrick’s side. “He’s a Kennedy,” the Boston Globe declared. “He’ll Make It.”

Pat, as the Globe took to calling him, occupies a small corner in Kennedy lore. He crops up for a few pages in books on the president or on his relationship with his wife. Most often, he is mentioned only in passing, if at all, as authors race on to the Nuclear Test Ban Treaty, civil rights, Vietnam or Dallas. This fleeting notice is fitting, perhaps, for Patrick’s presence was only temporary; he was allotted little time to carve out his place in the world. There are no ubiquitous photographs, as of the rest of the family. We are left to imagine a fragile infant described by those who glimpsed him as “beautifully formed.”

But an abundance of prayer and hovering doctors were not enough. Patrick’s tiny heart gave out, and he died just 39 hours into his journey.

Though he was gone too soon, Patrick had a profound impact on his mother and father. For Jackie, his loss was her latest childbearing trauma. She had already suffered a miscarriage and delivered a stillborn baby, and her son John Jr. also had been born prematurely and overcame his weak lungs. Measured against her sister-in-law Ethel, who delivered her eighth child around this time, Jackie was the Kennedy woman with the reputation for troubled pregnancies and births.

She also had endured years of anguish and embarrassment over her husband’s womanizing and inattention. When she gave birth to her stillborn child in 1956, JFK was on a yacht in the Mediterranean, reluctant to return home quickly to his devastated wife. With his cool detachment, he saw no reason to rush back — the baby was already lost. He relented only when wiser friends warned the ambitious senator from Massachusetts that if he didn’t race home, he’d never win the female vote in any future campaign for higher office. As noted in one Kennedy biography, his buddy Sen. George Smathers told him: “You better haul your ass back to your wife if you ever want to run for president.”

Since his callousness in 1956, JFK had gradually matured, thanks to the birth of Caroline and John Jr., both of whom he doted on. By the time Patrick arrived, the president may even have begun turning away from his manic philandering and may have been trying to be a more heedful husband. His behavior through Patrick’s birth and death can be seen as a step in that evolution.

With his wife stranded in the hospital on Cape Cod and his son at Children’s in Boston, JFK shuttled back and forth sleeplessly, carrying the latest updates to Jackie and returning to be by Patrick’s side. In an effort to save the child, doctors placed him in a steel hyperbaric chamber 31 feet long and 8 feet in diameter to force oxygen into his lungs. At first, the boy responded favorably, and Kennedy phoned Jackie with the news to keep her spirits up.

On Aug. 8, press secretary Pierre Salinger informed the world: “In the late afternoon, there was a halt in the downward trend in the baby’s condition. His respiration rate has gone down, he is breathing with less effort, and the laboratory tests taken since he was placed in the chamber show improvement.” Forgoing the Boston Ritz-Carlton, the president decided to sleep at the hospital.

But during the night, doctors watched helplessly as Patrick’s condition deteriorated. At 2 a.m., JFK was roused. His day-and-a-half-old son was in critical condition — he was losing his battle. Accompanied by his friend Dave Powers, the president made his way down a corridor of rooms filled with ailing children.

While waiting for the elevator, his eye wandered into a nearby room, falling on a small child who had been badly burned. JFK summoned the night nurse. He wanted to know how the accident happened. And how often did the mother visit the hospital? When he learned that the mother came every day, the president asked for her name. Taking a slip of paper and a pen from Powers, he scrawled a note of sympathy. “There he was, with his own baby dying downstairs,” Powers recalled in his memoir, “but he had to take the time to write a note to that poor woman, asking her to keep her courage up.”

Joined by his brother Robert, the president peered through a small window in the door to the room with the hyperbaric chamber. Only doctors in pressurized body suits and helmets were permitted inside, and for two hours JFK gazed in at his tiny son enclosed in the monstrous steel chamber. At about 4 a.m. on Aug. 9, the doctors were forced to admit that they could not stop the inevitable. Little Patrick Bouvier Kennedy had scarcely any life left. The infant was removed from the chamber and placed in his father’s arms, still alive. With Powers and Robert beside him, Kennedy cradled his son as the frail newborn took his last labored breaths. “He put up quite a fight,” the president said softly. “He was a beautiful baby.”

The president made his way back up to his room on the fourth floor at Children’s and asked Powers to phone his brother Ted. JFK sat on the edge of the bed as Powers closed the door. From outside the room, Powers heard what few ever heard: a Kennedy weeping. The president had given him the task of tracking down Ted, Powers said, because “he didn’t want anybody to see him crying.”

After the funeral Mass in Boston and burial in nearby Brookline, which Jackie missed because she was not well enough to travel, John spent long hours with her at the Otis Air Force Base hospital, describing the small family ceremony, the little white casket and the white flowers she wanted covering it, and they cried together. When Jackie finally left the hospital one week after giving birth, she and JFK came out of the green, bungalow-like building side by side. The president held her hand as she negotiated two small steps. Then the couple walked hand in hand several feet to a black limousine, Jackie smiling and cameras clicking. The president helped her get settled in her seat, then went around and climbed in beside her.

His new tenderness toward Jackie was obvious to all, and over the years it would be noted by biographers and in memoirs by those close to the couple. “After the death of Patrick, the other agents and I noticed a distinctly closer relationship, openly expressed, between the president and Mrs. Kennedy,” her Secret Service agent Clint Hill recalled in his memoir. “I first observed it in the hospital suite at Otis Air Force Base but it became publicly visible when Mrs. Kennedy was released from the hospital.” A clue, Hill said, was that the president and first lady emerged holding hands. “It was a small gesture, but quite significant to those of us who were around them all the time. Prior to this, they were much more restrained and less willing to express their close, loving relationship while out in public. The loss of Patrick seemed to be the catalyst to change all that.”

Salinger also noticed something new. “The death of the infant was one of the hardest moments in the lives of both President and Mrs. Kennedy,” he recalled. “The White House had brought about a closeness in their relationship, a wider understanding of one another. The death of their baby brought them even closer.”

How enduring their new closeness would have been is impossible to know. Barely three months after Patrick’s death, President Kennedy and his wife, Jackie, climbed into an open Lincoln Continental limousine for a ride through Dealey Plaza in Dallas.

steven.levingston@washpost.com

Read more from Outlook:

Why we keep writing about JFK

Friend us on Facebook and follow us on Twitter.