Conjoined twin brothers who share the same the same body and heart were born in Atlanta on Wednesday.

Asa and Eli Hamby - who can never be separated - were welcomed into the world at 7.32am via a pre-planned C-section to mum Robin and dad Michael and according to a dedicated 'Hamby Twins' Facebook page are healthy and well.

'Babies are out and so far they are doing amazing,' an 8am post declared about the 9 pounds, 10 ounce children, 'Both babies crying their little eyes out!!'

With no immediate complications, the boys are on oxygen masks as a precaution while doctors at Northside hospital in Atlanta examine them.

Born with two heads, but sharing one body, the condition Asa and Eli have is known as dicephalic parapagus - an extremely unusual form of conjoinment, affecting only one-in-a-million births.

Asa and Eli can never be separated because they share one heart and one circulatory system, The Daily Mail reports.

Both Robin and Michael are 34 and are being supported by their extended family, included Michael's father David, who has been wearing a T-shirt all morning embossed with 'Two souls sharing one heart.'

The rare and extremely risky pregnancy carried through to 37 weeks and Robin and Michael travelled from Alabama to Atlanta's Northside Hospital for specialist care.

The expert medical team at Northside, included two obstetricians who coached dad, Michael through the procedure up until he posted a video to his son's Facebook page early this morning.

'We are excited about the birth,' an anxious looking Michael said. 'We are nervous, scared. You name it, we are going through it.'

The next few days are vital for the Hamby Twins, especially in light of daunting statistics from the University of Maryland Medical Center which state that the only 35 percent of conjoined twins only survive one day.Indeed, the overall survival rate for conjoined twins, let alone those with Esa and Eli's conjoinment is between five and 25 percent.

While they share the same body, have one set of arms and legs and have two separate heads, doctors believe they also share the same heart and liver and amazingly, three lungs - one each and a shared third one. 

They have separate esophaguses, stomachs, intestines, kidneys (one each), ureters, bladders (fused together), gall bladders (fused together) and spinal cords.