O'Dwyer braved flooded roads to travel between Kerikeri and Kaikohe to reach the woman, who was with a GP.
"There was lots of water on the road but thankfully by the time I went through the flooding was isolated to half the road so I could at least go on some of the dry parts."
Time was of the essence and they called a Priority 1 ambulance to try to get the woman to Whangārei Hospital, but the roads were in a terrible state from the storm.
"It was quite stressful thinking we were going to have a 29-weeker that needs generally quite a reasonable amount of respitory support, so that was challenging", O'Dwyer said.
A midwife who worked for the local DHB was also called in to help.
They rang for a helicopter early this morning but the weather was too miserable, and then fog settled in.
A makeshift resuscitation table was prepared at the GP's surgery.
Finally by 9.30am one managed to land in a local park and the woman was transferred.
"I was very relieved that the helicopter arrived," O'Dwyer said.
"Fortunately we were able to slow her labour down sufficiently so that we were able to get her in the helicopter before the baby was born."
O'Dwyer wasn't sure how far off the baby was from being delivered because premature birth is so unpredictable.
"We were just really grateful that we were able to stop the labour in time so that we didn't end up having a little 29-weeker with inadequate care.
"A GP surgery is better than the side of the road by a long stretch, but it was really great that we were able to get her into Whangārei before anything happened."
New Zealand College of Midwives president Nicole Pihema said midwives and pregnant women were cut off across the region.
"Midwives are stranded, they're almost landlocked, or in this case water-locked.
"They're ensuring everyone has a home-birth kit with them and making sure they're available to provide birthing care for women who are locked by floods, because in many cases they can't get anywhere close to hospital."
Pihema said rural midwifery wasn't just about serving a community but also knowing it, which came in handy in such extreme weather events.
"You know the person who has a chainsaw, the father who has got a tractor that can get across a flowing river, someone who's got a boat or a kayak that can take gear across."