My daughter was 19 when she was hit by a car. I learned too late that I had no medical authority.

• Shawnee Baker's daughter, 19, suffered catastrophic brain injuries after being struck by a car.
• The mom couldn't make decisions about the student's medical situation as she had no healthcare proxy.
• Baker wants young adults to sign the document in case their family needs to make tough choices, too.

This story is based on a conversation with Shawnee Baker, a safety advocate for students and a former nurse from New Hampshire. It has been edited for length and clarity.

One afternoon during her senior year in 2017, my 18-year-old high schooler, Baylie Grogan, spoke to me in a serious tone.

"The only thing worse than dying is living in a body that doesn't work," she said. "Promise me you won't ever let me live that way."

It was shortly before she left home to start college as a pre-med student. "I promise," I replied, agreeing that such a predicament would be horrifying, and I wouldn't want it either.

I could never have imagined that I'd have to fight to keep my promise to my beautiful girl, who sustained catastrophic brain injuries the following year.

We were her next of kin

My husband, Scott, and I had no say in the life-or-death medical decisions affecting Baylie, who was given a 1% chance of survival after being struck by a car.

Despite being her next of kin, we were obliged to defer to the ethics committees of two hospitals because she was legally an adult at the age of 19.

Only we knew how much Baylie would have abhorred the idea of an incapacitated life of pain and isolation. Yet we had no voice.

Our daughter had always been happy, considerate, and responsible. She was friends with everyone. Academically gifted, she planned to be a doctor. She wanted to help others.

Her empathy extended to animals, especially her own horse. She'd go to the barn at 5 a.m. and spend hours with him after school. Her two older brothers and I would often call her in case she missed dinner.

I was 3 months pregnant with my 4th child

In the run-up to graduation, she selected the University of Miami as her first choice of college, mostly because it had a renowned equestrian program.

She loved her time as a freshman and, after spending the summer of 2018 at our home in New Hampshire, studying, lifeguarding, and working part-time, she was ready to return.

In mid-August, we flew to Miami, where I helped her move into her dorm. We cried when we kissed goodbye. I was three months pregnant at the time, and she thought I might be feeling vulnerable.

"I love you so much, Mom," Baylie said. "I love you, too," I said.

It was the last time I'd ever get to see the same kind, smart, vivacious Baylie I'd always known, the world at her feet.

Just days later, on August 19, 2018, I received a call from the Miami-Dade police department. "There's been a terrible accident," the officer said. "Baylie is alive, but you need to come to Miami immediately."

Baylie was in the operating room

He couldn't give more information over the phone and told us to contact the hospital where she'd been admitted. They said Baylie was in the OR, and the surgeon would call us as soon as he could.

I was distraught and kept asking myself, "Was she in surgery for a broken pelvis or broken leg, or something more serious? Did she hit her head?"

We had a torturous journey south to the hospital in Miami, where Scott and I were shown to Baylie's room.

I'd worked as a nurse in the ER for four years, and my daughter was, by far, the worst patient I'd ever seen. Her face was bruised and bandaged all over. Her body was swollen to four times its size.

She was hit by a car

She was on a ventilator, and her hair had been shaved off. There was a C-shaped scar on her scalp from the brain surgery and tubes coming out of her head. I ran to the bathroom and vomited in shock.

The police informed us that Baylie had been caught on traffic cameras crossing six lanes of I-95 on foot in the early hours of the morning. She'd been hit by a car after becoming separated from her friends on a night out.

I tried my best to hold out hope, but it seemed pointless. Baylie's brain activity was barely detectable, and her pupils were unresponsive to light. They were signs of irreversible brain damage.

She was later transferred by plane to a Boston hospital that was closer to our home. The neurological team detected a so-called Duret hemorrhage in her brain, a bleed that almost certainly signals full incapacitation.

We were faced with legal obstacles

We knew that, in the 1% chance she survived, she would be in a persistent vegetative state — the scenario I'd promised not to allow.

Scott and I hit hurdles from the very beginning. We didn't have the legal right to request a toxicology report when she was admitted on August 19, which may have helped address our questions about whether she'd been drugged.

Baylie had never completed an advance directive, healthcare proxy, or HIPAA waiver, which are available to adults 18 and over. Obtaining guardianship through the courts was likely to take months.

We were not allowed to see her medical records or make important decisions about her care.

Without a healthcare proxy or DNR order, she was repeatedly resuscitated by default. In hindsight, I wish we hadn't taken those measures, no matter how heroic the hospital staff was. Baylie was meant to leave us the day she got hit by the car, but her suffering was prolonged.

The ethics committees of both hospitals were there at every turn. Appointed to make decisions on Baylie's behalf, it was up to strangers — not us — to judge whether her quality of life justified being taken off life support.

Baylie had a functional MRI

I felt not only grief, but also frustration about letting Baylie down. We were powerless, despite the knowledge that our daughter would hate the semblance of a life under 24-hour supervision in a long-term care facility, unable to open her eyes, feed herself, or recognize her family.

She had a functional MRI, and the committee decided to interview 10 people who knew Baylie well. The members asked them if she would want to suffer under those conditions. Everyone said no.

There was more back and forth, but we finally heard that Baylie could be moved to palliative care on September 24. It was unbearable, but she died with dignity and without suffering on September 27. I'd kept my promise.

I miss her every day

The last seven years have been hard. I miss Baylie every day. I gave birth to Baylie's little sister, Savannah, in 2019, and her youngest sibling, Seraphina, two years later. They have brought much joy and laughter.

We vowed to honor Baylie's memory and founded Baylie's Wish Foundation. It advises students to take a few minutes to complete documents, such as healthcare proxies and HIPAA waivers, so that their loved ones can respect their wishes if a medical crisis were to happen.

You can download relevant forms for each state from our website for free. We want colleges to automatically include them in the paperwork sent to incoming students.

I know that Baylie would be proud of the campaign in her name. She wanted to help people. We're seeing that through.

Editor's note: Business Insider contacted the hospitals that treated Baylie Grogan and is awaiting a response.