He went outside and saw more smoke and the beginnings of fire coming from cracks in the chimney. He woke his partner and their 2-year-old and tried to put the fire out.
"I tried with the garden hose, but the hose had no fitting. I couldn't do anything to put it out."
The woman called 111 and her midwife. Meanwhile, the man moved the couple's bed onto the lawn for his partner to lie on as her labour continued.
They considered going to hospital but were able to return to their house after about 30 minutes, once firefighters had extinguished the blaze.
"We were pretty lucky. By the time the fire truck got here it was flaming. If they were two minutes later it would have got in to the roof and there would be nothing left," the man said.
"If I'd been asleep in the bedroom like normal, there's no way I would have woken up."
The couple did not have working smoke alarms but would not be without them in the future, the man said.
"The two things I'd really like to emphasise is the need to have smoke alarms and how amazing the fire guys were. They came in, sorted it out then and there. They did a great job."
The couple's son, Bayley, was born at home, just before 11am yesterday.
Tauranga Fire Brigade Senior Station Officer Mark Keller said the chimney was unusual and dog-legged to the exterior of the building.
The fire began where the flue and the wall met, he said.
