I didn't have a violent birth with DD or almost die but it was traumatic enough to me mentally to cause PTSD (diagnosed by my doctor and therapist, my HV went for PND first).
In my case it was a combination of my upbringing and treatment by the hospital that caused it.
I don't talk about it to people because they either assume it was PND or want to know what happened and will then assume it 'wasn't that bad'.
I'm coming out the other side now but for the first three years afterwards I couldn't even hear the word birth without an intense physical reaction; also seven years of flashbacks, nightmares, feeling completely numb except for extreme emotions, incredible terror of getting pregnant again, insomnia, being on alert and paranoid all the time, angry and irritable and in a constant state of panic and stress. I thought about suicide and came very close to doing it twice. It has impacted me physically as well and I have been unwell for years.
I had a breakdown/collapse and have received some help recently and feel like I am starting to come out the other side, I can actually feel happy and laugh again. Even my DH and DM had no idea I was suffering so badly as I hid it so well.