The heartbreaking reason this woman had an abortion at six months of pregnancy.

Kylie Gunn and her husband were overjoyed when they discovered she was pregnant with a baby boy.

They settled on a name they both adored: Travis.

“I desperately wanted a boy. I was in such joy,” Ms Gunn told MailOnline.

But their bliss was shattered when doctors discovered their unborn son was suffering from several rare and fatal medical conditions.

The 37-year-old New Zealand nurse was forced to make one of the toughest choices of her life.

Travis had the deletion of the 22nd chromosome and severe heart defects. He would never walk, he had a 99 per cent chance of dying with his first infection, and he had minutes to two years to live if he made it through the operations he needed allowing him to breathe on his own.

“Rather than bring him to term and allow invasive procedures to take over his short lifespan – a life that would have limited contact with me and those who loved him, and a life incapable of ever knowing that love, I chose to abort his life,” she wrote in Stuff.co.nz.

“One surgeon said he would support us keeping our baby, but that the heart surgeries would be only for their education, without much hope of ever allowing Travis to breath alone.”

At 24 weeks pregnant, she underwent the abortion. She did not know until three weeks earlier that Travis had such serious medical problems.

She was induced into a “very painful” labour.

“It took quite some time. My body did not want to let him go,” she said.

When Travis emerged, she broke down into controllable tears for her lost son as doctors placed him in her arms.

"I did not know what it was to keen (a loud wailing, a lament for the dead) until the moment he came out still in his (amniotic) sack, and I held him and said goodbye. I will never forget," she wrote.

She found herself gripped by grief for a long time.

"I was grieving as much as if I had lost a child I already knew. We wanted Travis. It's different from having an abortion because a baby is destroying your hopes and dreams," she said.

This Wednesday would normally have been Travis' 12th birthday, one he should have been able to celebrate with his parents, three older siblings and three younger ones.

Ms Gunn still loves him. But she is at peace with her decision, believing it was the right thing to do.

She wrote her open letter in Stuff.co.nz calling on pregnant women to be educated on all options available to them, including adoption. She warned the lack of information on alternatives left women at higher risk of depression, anxiety, crippling regret and isolation.