Perth father left to raise his newborn son alone after rare condition claims the life of his fiancée

A Perth father will raise his little boy alone after his fiancée died during childbirth from a complication so rare doctors had no chance of diagnosing it.

Kymberlie Shepherd suffered Amniotic Fluid Embolism during labour, a condition which affects six in every 100,000 child births.

Doctors worked to save Ms Shepherd for more than two hours but were unable to revive her.

Her fiancée Wayde Kelly, 26, said it was the most traumatic thing he had ever seen.

"She was just going blue, I just felt sick. My legs went, I was just at a loss," he said.

Baby Kyden was delivered via emergency caesarean.

Mr Kelly told 9NEWS he is comforted by the support he has received.

"I've been getting messages from people I don't know ... It's just been so overwhelming," he said.

Mr Kelly and Kyden will move back to Ms Shepherd's home state of Queensland to be closer to her family.

If you would like to donate to help support baby Kyden, visit this website.