However, Antrim Crown Court Judge Desmond Marrinan told Richard 'Rickie' Joseph Fullerton that what he did was "despicable" for which he rightly felt shame and remorse.
Fullerton, 20 and from Leckagh Drive, Magherafelt, was cleared last month of the more serious charge of assaulting his former girlfriend in February 2010 with intent to procure a miscarriage after the prosecution offered no further evidence, when he admitted the lesser charge of common assault.
His forgiving former girlfriend, who never wanted him jailed, but wishes to remain anonymous to protect her daughter, said she was "happy enough" with the sentence Fullerton was given.
She and her grandmother both said that all they wanted now was to "get on with our lives and to put this all behind us".
Earlier, they had listened as Judge Marrinan said that despite the changes in social values, to his mind, it was still shocking that as a young teenager, Fullerton had engaged in a sexual relationship with a young schoolgirl.
He also told Fullerton, if at the time, he had been a man, or even a little older he "would have had no hesitation in sending you to jail".
Judge Marrinan said at a time when his former girlfriend needed his support on discovering she was pregnant, he shamefully struck out at the girl he claimed to love.
However, he added that Fullerton then, was no more than a youngster himself, and he had wrongly acted out of panic, and it was something that will stay with him for the rest of his life.
Last month, the court heard a taped police interview, in which the then teenage girl explained that when she told him a pregnancy test "had come back positive", a "very upset and annoyed" Fullerton said the test may have been "mixed up".
However, when she then "turned round to give him a hug he punched me in the stomach twice ...full force punch ... just below the belly button".
She said as she "sat on the bed doubled in two" her younger brother came in asking what was wrong, only for Fullerton to tell him that she had "a sore stomach", while she herself "felt sick".
Afterwards she said she thought it was "really sad" as she did not think he would do anything like that.
Asked why she had been punched, she said it was because Fullerton "didn't want me to have the baby".
She also revealed that in the following weeks, her fears proved only too true. In several texted phone messages, Fullerton gave her an ultimatum, either him or their unborn child.
He even encouraged her to slip off to England for a supposed holiday, but in reality to seek an abortion, something she refused to do.
"I didn't want to go to England to have an abortion. I remember people saying if you ever have an abortion you will regret it," she told police.
Defence lawyer Michael Ford said on Monday that despite Fullerton's offending, a healthy and happy young child was born, and by his guilty plea he had saved his former girlfriend of having to go through the strain of appearing in court.
Mr Ford said that when told of the pregnancy, a young Fullerton had hit out in a momentary lapse of self-control, and has been candid enough to acknowledge that having panicked and lashed out, his actions were unacceptable and reckless.
Judge Marrinan, in suspending Fullerton's two month detention sentence for a year, said his hand was "stayed", given his clear record, guilty plea and positive reports showing he was actually growing into a decent young man.
However, Judge Marrinan added the case was a timely reminder that men, young and old, must treat their partners, or girlfriends with the respect they deserve.