A pregnant teen in a class by herself Maddie Runkles wasn't allowed to walk at graduation because she was pregnant.

 -- Maddi Runkles was a straight-A student, president of the student council and a star of the varsity soccer team. But her high school, Heritage Academy, banned her from attending graduation ceremonies with her classmates.

That’s because the Boonsboro, Maryland, teen became pregnant.

A few months ago, Runkles, now 18, said she felt like she had the flu, but it wouldn’t go away, so she knew something was up.

“I decided to go get a test, just to be sure, and I found out I was pregnant that way,” she said.

Runkles said she was scared at first and couldn’t believe this had happened to her.

“I wanted to go have an abortion because I was scared to death what people would think of me,” she said. “My reputation, I thought it would be ruined.”

For Runkles, keeping the baby required a leap of faith. She knew full well her Christian school would disapprove of her being a single teenage mother.

Indeed, Heritage Academy treated Runkles’ pregnancy as a violation of its strict moral code. The baby’s father was not a student at Heritage and was already in college at the time, so the school punished Runkles alone.

“Even though we love Maddi, even though we forgive her, there’s still accountability,” Principal Dave Hobbs told ABC affiliate WJLA. “This has been a breach of the standard of abstinence.”

Hobbs declined ABC News' "Nightline"'s interview requests.

The principal suspended Runkles for two days while the school board weighed her punishment. Hobbs then decided to inform the school in what some called a public shaming.

“There was an all school assembly that was called by the principal, Mr. Hobbs, and he sent a letter out to the ninth through 12th-grade parents letting them know that something had come up,” said Maddi Runkles’ mother, Sharon Runkles. “He didn't want her there and then she said, ‘No I'm going to be there.’”

Maddi Runkles asked Hobbs if she could personally address the school and ask for forgiveness.

“I apologize to all of you for any disappointment that I may have caused,” Maddi Runkles said, reading from the letter she wrote to her classmates. “But right now I need your love and support more than your judgment. Christians should be defined by grace and love not hate. I ask each of you to please support me as I go through my pregnancy.”

But despite her pleas, the school handed down a severe punishment.

“She was not allowed back on campus, and we also have a son at the time he was in ninth grade very active in sports,” Sharon Runkles said.“She wasn't allowed to attend any of his sporting events as a spectator and she also couldn't be on the campus at all.”

Maddi Runkles’ father, Scott Runkles, was on the school board but decided to resign. While he says he knew his daughter deserved some punishment, he appealed to the school to allow her to come back.

The school agreed, contingent on a couple of conditions.

“She has all the rights and privileges of a normal regular student with the exception that she cannot walk in graduation and she is to be removed from leadership positions,” Scott Runkles said.

Maddi Runkles returned to school after a couple of days, but she said things had changed.

“[There were] some people that kind of were OK with her being there, now they weren't,” Sharon Runkles said. “Some of the teachers had stopped talking to Maddi. They didn't even acknowledge her. They were told the principal had told some teachers to sit her in the back of the classroom.”

“Basically it was like punishing her again like, she was a scarlet letter,” she added.

In his interview with WJLA, Hobbs saw the situation differently, saying, “Discipline is not the absence of love. Discipline is the application of love."

In an open letter dated May 23, Hobbs also said, "The Board has listened to three appeals from the Runkles family and compromised all three times."

Kristen Hawkins runs Students for Life, an anti-abortion group that does outreach on campuses nationwide, and she believes the school was shaming Maddi Runkles.

"Why would you call an all-school assembly, inviting students, parents, and faculty and say you’re going to announce to the entire school the sins of one student?” Hawkins said. “[The school] said they love Maddi but that she was immoral. Well, all of us are immoral, we’re all sinners. We’ve all fallen short of the glory of God. It’s why we seek salvation."

She said she understands that the school needed to punish Runkles for breaking their moral code, but she says the school failed to acknowledge the courage of her choice to keep the baby.

“This is about, ‘What does it look like for our school?’ And I think this is a question a lot of Christian schools have to grapple with, holding our students to high standards and expecting them to practice chastity before marriage,” Hawkins said. “But then, also, how do we love those who become pregnant and how do we not shame them?”

Maddi Runkles worries that more girls could be driven into seeking abortions if they know her story. “If I were another girl watching someone like me go through this, I think I would just run away and hide and cover up what I did and choose an abortion. And if the next girl or even guy who gets a girl pregnant doesn’t have the support from their family like I do, and they only have the school to turn to, then I think definitely that it would drive them to make the wrong decision.”

Teen pregnancy, birth and abortion rates in the United States are now at historic lows, according to Guttmacher Institute, a leading research and policy organization for advancing sexual and reproductive health and rights in the U.S., in large part because of sex education and access to contraception.

According to Guttmacher, more than half of the young girls who decide on abortion identify themselves as Christian.

But not every school handles an unwanted teen pregnancy like Heritage. Many schools, even Christian ones, show compassion and forgiveness.

That was Liz McNitt’s experience. She is the 21-year-old mother of an adorable toddler. She was a 17-year-old senior at a Catholic high school in Boalsburg, Pennsylvania, when she found out she was pregnant.

“I told my friend that day and I asked her if she could go to Wal-Mart with me. … We bought a pregnancy test and I took it in the bathroom,” she said. “I think we stayed in the bathroom after reading a pregnancy test for a solid two hours. … I cried a lot and cursed a lot.”

She had little idea at the time how being pregnant would change her life.

“I didn't know what kind of support I was going to get,” McNitt said. “I was I think most scared about my capabilities as a mom. That was the scariest part. But I was also really scared of the social kind of aspect. I didn't know how people were going to receive it.”

But her fears were quickly put to rest after confiding in her high school counselor Jean Kozak.

“She came in and she basically was crying one day and basically came in and she said ‘I’m pregnant,’” Kozak said. “And she was sobbing and sobbing and because I knew her and knew her value systems and her own faith experience, I basically just took a breath and looked at her and I said congratulations you’ll be a wonderful mom..”

McNitt says that was a “crazy moment” for her.

“I was a little bit shocked but it was the first time that I thought of myself as a mom which was crazy. It was the first time I thought maybe I could do this," she said. “This woman who I had a lot of respect for who was one of the most faithful people I know, trusted me and believed in me and didn't judge me. There was no shaming.”

“We certainly don’t encourage, you know, the sexuality before marriage,” Kozak added, “but we certainly acknowledge the fact that people are people. And so in Liz’s situation we basically, in a faith-based community we basically encourage the birth of the child.”

McNitt’s school celebrated her having her baby.

“I saw no whispers no shuffles away in the hallway. I had a teacher come up to me with tears and say, ‘Thank you for keeping your baby,’” she said.

At five months pregnant, McNitt not only walked at graduation, she was elected to be the commencement speaker and was honored with an award for her faith.

It was a stark contract to Maddi Runkles’ high school graduation experience. Instead of graduating with her classmates, her parents and her pastor arranged a private ceremony for her. She graduated, quite literally, in a class by herself. Her graduation party was also a baby shower.

Maddi Runkles has since become a cause celebre in the anti-abortion community, which has been sharply critical of Heritage Academy’s response to her situation.

After the controversy made headlines, Runkles said she got a call from Bob Jones University, a college known being culturally conservative, saying she and her baby were welcome at their campus. She has also received an entire room full of baby presents from strangers who supported her decision.

“I know what I did was not what I was supposed to do to get into the situation,” Maddi Runkles said. “But keeping the baby is definitely not a mistake. I know that it was the right thing and feeling those little kicks and everything just makes me know that all this really is worth it.”

It’s not exactly the path her parents had dreamed of for their daughter, but they remain proud. Maddi Runkles is due to give birth to a baby boy in September.

“I can't wait to see this little boy, to actually be able to hold him, to really see this kind of come to fruition and actually see this little boy in our home,” said Scott Runkles.

She said she’s going to call him Grayson -- “Gray” for short.

“I’ve been given this baby and I need to accept the fact that I have -- and I do,” she said. “It’s going to be OK and I’m excited now I’m going to be a mom.”

Editor's note: An earlier version of this story incorrectly reported Maddi Runkles received a full scholarship from Bob Jones University. The report has been edited to reflect the change.