THE PARENTS: Sandy Kerstetter, 36, and Adam LaPierre, 40, of West Mount Airy

THE CHILD: William Hudson, born June 2, 2018

ADVICE THAT’S PROVED TRUE: Shortly after the couple met, a friend advised Sandy: There are no wrong decisions. It’s just life. “I’ve always kept that in the back of my mind,” she says.

Plenty of books, articles, and podcasts described post-partum depression. But no one told Sandy about the gloom where she might flounder before the birth.

No one told her she might wake up at 2 a.m. and sob for an hour. No one whispered about the twist of fear and anxiety and loneliness that could plague a pregnancy that was, physically speaking, textbook-perfect.

It didn’t help that Adam was often 30,000 feet and a time zone away, trying to rack up overtime as a commercial airline pilot so he could take paternity leave after the baby came.

“I was scared,” Sandy recalls. “I’d go to my doctor and say, ‘I feel like a crazy person. I’m crying all the time. I’m an anxious wreck.’ They’d say, ‘It’s just hormones.’ I’d see so many of my friends who said, ‘I love being pregnant.’ But I felt detached. I was worried: Would I be OK as a mom?”

Friends helped: people who coaxed Sandy out of the house during the bleakest winter days, who offered hugs, who came over just to sit on the porch for 10 minutes and talk.

Running helped, too. That’s how she and Adam met, after all, striking up a conversation at a party after the 2016 Philly 10K. Sandy had recently lost her most loyal running companion, her Australian shepherd, Jake. As she and Adam became friends, he encouraged her to try longer distances and introduced her to his extended family of exercise buddies: the November Project and Chasing Trail.

There wasn’t an official first date — more of a gradual segue from running to cooking to camping to confiding in each other about their lives. “Pretty early on, we were saying, ‘You’re my person,’ ” Sandy recalls.

From time to time, they talked about kids. Sandy, who is one of eight siblings and who became an aunt at 7, wasn’t sure she wanted more children in her life. Besides, they were still learning to navigate a schedule complicated by Adam’s work — typically, he’s gone four days a week, then home for three. A night owl, he’d be ready to Skype at 10:30 p.m. from a hotel room in the Midwest while Sandy would have been asleep for two hours.

He was in North Carolina with a broken cellphone the day Sandy decided to take a pregnancy test. “Will was not planned,” she says. “He happened. I was 35 at the time. For me, it was: OK, I guess this is the universe telling me this is the track my life needs to go on.”

Adam remembers a similarly pragmatic response: “OK. Great. This is happening.” He’d always wanted kids but figured they’d enter the picture in a more conventional sequence: college, marriage, house, children. He and Sandy had no plans to marry, and he’d bought the house on his own before they met. “It was always my goal to have a family,” he says. “I did that — but backwards.”

For months, Sandy sipped ginger ale at bar gatherings and told friends that she was the designated driver or that she avoided alcohol when training for a run. It wasn’t that she felt loath to share news of the pregnancy; she preferred to tell people in a more intimate fashion, one or two at a time.

When they decided to share the news with Adam’s mother, who is fluent in French, they took her to dinner at Parc and presented her with a onesie reading “J’aime ma grandmère” (“I love my grandma”). She burst into a torrent of delighted French. They gave other family members copies of the first ultrasound image, with a note: Coming in summer 2018.

But not swiftly. Labor was a several-day ordeal: a full-term induction because the baby’s heart rate was dropping followed by 25 hours with Sandy stalled at nine centimeters dilation, just shy of the 10 needed to push.

“It was the equivalent of being at mile 25 on the marathon,” she says. And when an obstetrics resident finally mentioned the C-word, Sandy ordered him out of the room. “I felt like I had to have a vaginal birth, like having him cut out of me was so impersonal. I felt like an absolute failure.”

Finally, after more time and no discernible progress, she agreed to the C-section. Her whole body shook as orderlies wheeled her to the operating room. Adam followed, with his mother’s professional camera in hand to capture every Technicolor moment.

When William emerged — purple and healthy and strong enough to grip his father’s finger — Sandy blurted, “Oh, my God, he looks like me!” A nurse brought the swaddled infant over to her. “He was crying, all bundled up. They put his face next to mine. I said, ‘Shh…Mommy’s here.’ He just stopped crying, and all the fear, all the pre-partum strife, went out the window.”

The day they left the hospital, Adam and Sandy took Will to Quizzo night at Goat Hollow. The next morning, he snoozed through a November Project workout on the steps of the Art Museum. He’s traveled to eight states, hiked a piece of the Appalachian Trail, attended a Phillies game and an Eagles game, gone tailgating and trick-or-treating, and crossed the finish line of the Philly 10K in his mother’s arms.

Each morning, whether Adam is in town or not, Sandy records a 15-second video of Will responding to some kind of music. As an infant, he seemed to love rap; more recently, he attempted a few baby push-ups to the tune of “ABC” by the Jackson 5.

The couple’s running friends, who wake early, love the videos and have begun to make musical requests. And Adam, perhaps seated in a cockpit somewhere over the United States, knows that when he comes in for a landing, a glimpse of his son, rocking out to Elton John or the Beatles or the Cure, will be waiting on his phone.