Gourdie politely refused to comment about the incident further, but admitted to the Weekend Herald that the incident was "crazy".
A Jetstar spokesman said they had apologised to Gourdie and had refunded all her flight costs.
The airline acknowledged that its policy differed to other airlines in that it required passengers from the 28-week mark to carry a letter from a registered doctor or midwife.
The letter must show the estimated date of delivery, whether or not the woman was pregnant with one child or multiple and that there were no complications.
"If staff believe a passenger may be more than 28 weeks' pregnant, they are trained to inquire if a medical certificate might be required - in line with our pregnancy policy."
Asked why airline staff failed to check Gourdie's details before boarding, the spokesman said: "This could take place at check-in, during boarding or once on board."
NZ College of Midwives midwifery adviser Dr Lesley Dixon said many pregnant women could travel late into their pregnancies. But airlines sought to cover their bases in case a woman went into labour.
"What they're looking at is the likelihood that the woman's going to go into labour whilst she's on their plane and they're going to be held to account for the woman's health."
Dr Dixon said there was no harm in flying if a woman was pregnant, but she needed to be aware of taking care of herself - particularly during longer flights.
"It's not that you can't fly when you're pregnant, but ... about making sure that you're moving a lot, wearing some support tights and being relatively careful."
An Air New Zealand spokeswoman said the company did not want to comment, but pointed out that its policy was that a pregnant woman could fly up to the end of her 35th week for flights over five hours and up to her 37th week for shorter trips.
