Another thing that we did was for DP to listen to the CD as well. He didn't listen as much as I did but he did it quite a bit. Then in labour he centred me with my breathing and relaxation. I found it was really a team effort and he was a big part of it.
I also think that if you are listening and fall asleep on occasion that's O.K. The words are still going into your mind subconsciously and most of all you are in a relaxed state and doing the breathing as you fall asleep.
Bookmarks