Both my very early Premmies have ongoing respiratory issues, they are usually in some level of respiratory distress and as soon as I mention they are ex 28 and 25 weekers we are taken pretty much straight away, I have never waited more than 10 minutes.
I took my DD2 (35 weeker) in with extremely high temps, in pain and very lethargic and we waited nearly 2 hours, turned out she had swine flu and was very sick.
So even though DD2 looked sicker than DD3 and DS4 she waited longer because resp distress can potentially be more serious.
I have been given evils by other parents because we have gone in so quickly and it may not look obvious what was wrong.

