"It was just a bit of a roller-coaster," Megan told the Herald on Sunday.
"She would have days where she would just stop breathing and we could not get her oxygen rate back up and [the doctors] would have to resuscitate her," she said.
"That was just really hard to see, your little precious baby go purple and have to wait for the medical teams to work on her. It was just really, really difficult."
But something that eased the struggle was the support from the hospital medical staff and the Neonatal Trust New Zealand - a charity that helps families with babies in Nicu units around the country.
The Spences are sharing their story to let others with premature babies know they're not alone and to raise awareness of the organisation, which has been awarded a $30,000 grant from Jetstar as part of the airline's Flying Start charity programme.
The grant is made up of $15,000 in flights and $15,000 cash.
The money will be used to provide 800 families with babies in Nicu with newborn support packs and to upgrade Nicu units in Dunedin, Hawke's Bay and Christchurch to match the service available in Nicu units in Auckland and Wellington.
Neil O'Styke, Neonatal Trust executive director, said a premature baby was born every 90 minutes in New Zealand and had to stay in Nicu.
As well as support packs, which contain information and a gift (usually booties and a hat), the charity provided lunches for families, organised playgroups for Nicu families and helped with accommodation and travel costs.
The Spences were given a support pack when Hannah-Ruth was born and a hamper of chocolates and other goodies on Father's Day about 10 days later.
The couple also catch up with other Nicu parents and Josh said it could feel isolating to have a baby in Nicu and having someone else to talk to about life in the ward was helpful.
"Knowing that they have an understanding of what you're going through and to provide the support that we needed to get through our journey was such a blessing - and a comfort, too, knowing that you're not the only one, that there are others who have started off like we did and have come through and have now got healthy kids at school or teenagers."
It was exciting the trust was getting a grant from Jetstar. "Knowing there are business out there willing to help and support people in such vulnerable times is a real encouragement."
Megan said the donation would help relieve the stress of parents with babies in Nicu.
"I think if you can just eliminate any stresses it's huge. Being in Nicu with a little baby that you're not sure will even live, even figuring out what to eat that night is really stressful."