I have had it with all 3.

DS1 i was in labour for hours and in the end had my waters broken, once this was done they realised i had meconium in my waters. From then on i had to have the monitor on my belly. Would have loved to hop in the bath but was not allowed. My labour was quite long and things were slow to progress so i think there was talk of a c-section (unbeknown to me at the time) if he became distressed but he never did. At the time i was aware it was that bub had pooed and usally from distress but he stayed so calm the whole time.
At the time i knew that it could be dangerous but not why. It wasn't until after i had DS and was watching a TV show that i was aware of just how dangerous it could be. From what i remember it was described as being like tar and turns the lungs from being like a spong to not being able to absorb anything.

DS2 my waters broke when i got out of the shower and they were tinged green. I was in no pain at all at this stage. I had a dr's appt which i went to and i was told to pack my bags and go to the hospital. I wanted to wait for labour to start itself but i was not allowed to. Upon examination it was discovered that it was my hind waters but they still progressed with induction. I was also hoping to labour in the spa and possible have a water birth but was not allowed to.

DD i had laboured at home all day, arrived at the hospital and my waters broke about 15 min later. Once again meconium in my waters. Once DD was born she actually continued to poo all over my tummy.

So for me i had it each time. I was as calm as could be expected and i don't see that my children would have been overly distressed either. After seeing that documentary though with the little one in special care and the tubes everywhere i know it can be a very serious issue. Thankfuly it never was for me.

So how to know if it could happen again or possibly prevent it i don't know. But i dont think you really want to take your chances with it.