Yep. I had a 4th degree tear with my first (vacuum delivery) and a lateral episiotomy with my 2nd (forceps delivery, I had bad luck!).
For my UC I birthed on hands and knees and tore into the original scar on my perineum (into the muscle). I suspect if I could have slowed him down a little the tear would not have been as bad. I wasn't really expecting his head with that contraction, but it shot right down and out with one push. If I had realised I might have tried to pant a little!
I did a lot of research before my 2nd birth, and a repeat 4th degree tear is very unlikely with a natural birth - something like 5%
Ouch! Did you go to a midwife or to a dr. for repair?
eta- Are there positions that m/ws specifically recommend for protecting the perineum?
We were going to take the baby for his newborn check at the hospital (it was a "oops, it was all so fast" arrangement). As it happened, my placenta wouldn't come, so we were there anyway for that. I would love to experience PP with no stitches!
From the research I did, it seems that all fours or side lying are easier on the perineum, also birthing in water. I think a full squat increased the risk slightly, maybe because the baby can come faster like mine did? I read the same as you - that you will naturally assume the best position given the chance.