I think walking on a extreamly calm horse is ok. But trotting and faster may end up jumbling the baby up and possibly causing some damage. And there is always the risk of falling off and hurting the baby. I'd ask a doctor for more deffinate answers.
Well, depends on the person and body, and how pregnant you are. Some people are more sensitive.
There was another thread like this before and some people mentioned how they stopped riding (walk, trot) at 6 months because they were too big and it wasn't comfortable anymore. Others trotted and cantered until 7 months... others barely rode at all. Really depends.
Depends on you, how you are carrying, how stable your pregnancy is, wht your horse is like and what you are doing.
Mum rode when carrying me, she was very fit and active, healthy had no issues with her pregnancy, she stuck to walk for the first 3 months and then continued to hack out and ride on the flat in the school on safe older horses practically up to the day I was born with absolutly no issues. It is the standing joke that I was nearly born in the saddle as mums waters broke at the stable yard.
With my brother on the other hand mum had a difficult pregnancy and did not ride at all.
I would take advice from your doctor and midwife, they will be more likely to know your unique situation and how well your body is likely to tolerate it. I personaly would not be jumping (couldnt live with myself if I had a fall and miscarried) but several top eventers have continued to compete whilst pregnant and I'm fairly sure one top dressage name did as well.
I listened to my body and rode almost my entire pregnancy, I really maintained the same activity level my entire pregnancy. I moved several hundred bales of hay with a few friends just a month before I delivered! I did not consult with my doctor on really anything that I did because I feel they always lean towards being overly cautious out of fear of being sued.