A transgender man has given birth to a healthy baby - five years after having his first child while living as a woman.

Kaci Sullivan is believed to be the first person in the world to give birth while living as both a woman and a man.

The 30-year-old underwent a C-section following seven days in labour and welcomed Phoenix into the world four years after beginning the transition from female to male.

View photos A transgender man has given birth to a healthy baby - five years after having his first child while living as a woman. Photo: MEGA More

View photos Kaci Sullivan is believed to be the first person in the world to give birth while living as both a woman and a man. Photo: MEGA More

View photos The 30-year-old underwent a C-section following seven days in labour and welcomed Phoenix into the world four years after beginning the transition from female to male. Photo: MEGA More

Business student Kaci conceived with 27-year-old partner Steven last February after taking a break from male hormones.

The couple do not want to reveal the 8lbs 9oz baby's sex and will raise it as 'gender neutral' until it is old enough to decide its sexuality for itself.

Kaci already had one child, five-year-old Grayson, with his ex-husband, who he gave birth to while living as a woman before coming out as transgender.

"Some people have been perturbed by the idea of me giving birth but I don't engage or respond to them,” Kaci, from Wisconsin, said.

"Because I don't see pregnancy as inherently feminine, and because I don't subscribe to make-believe gender roles, I wasn't threatened by the idea of pregnancy.”

View photos Business student Kaci conceived with 27-year-old partner Steven last February after taking a break from male hormones. Photo: MEGA More