Pearl Joy Brown was born with a rare genetic disorder causing her brain’s development to stall in the first weeks of pregnancy, leaving her with a cleft upper lip, and a three per cent chance of survival.

A routine ultrasound four month into the pregnancy revealed that Ruth, 28, and Eric, 31, Brown's unborn daughter had alobar holoprosencephaly, and specialists said she would most likely not make it to term.

Faced with religious, medical and ethical decisions, the Nashville couple refused to terminate their pregnancy early. Now, despite the fact doctors have given Pearl a year to live, who will likely never walk, read or speak, her parents are fighting for her survival.

Mr Brown The Tennessean: 'If there is a chance, you say yes to that chance. The only thing I know about parenting is that you say yes.'

The couple, who have two children, Brennan, 5, and Abbey, 3, celebrated Pearl's 12-week-old birthday today, and say they are taking each day at a time. 

According to the Dallas-based Carter Centers for Brain Research in Holoprosencephaly and Related Malformations, only three per cent of babies diagnosed with Pearl’s genetic condition, where her brain never divided into two hemispheres, actually survive birth.

'We didn’t think she was going to be able to breathe,' Mr Brown admitted. 'She is here, and her brain is telling her how to live.

'God has designed Pearl the way he wanted, for his glory and our goo