Not much help here, as I became a horse owner long after my boys were born (and grown into young men!) but I'm quite sure I would feel 100% confident on gentle rides with either of my current mares throughout both pregnancies, as I felt terrific - only you and your doctor can determine your exact circumstance. Congratulations! :)
My SIL did trail rides for an outfitter all summer while she was preggers. The last ride she did she was 8mo along. The people she was taking always looked at her funny. Her doctor told her if it didn't hurt her it didn't hurt the baby. She has been riding her whole life so her muscles/body were conditioned for it. She would NOT have lasted 9 months without riding. Good luck on your pregnancy! I hope you are comfortable (physically) enough to ride during most of it.
I rode for about 5 months. Husband had a fit and put a nix on it after that though. I see a lot of people competing all the way up until 8 months. I would think if you are on a reliable horse and you are comfortable and healthy then you should be ok. Just remember the inherent risk....
My Dr says its fine as long as I'm comfortable and I rode during my other 2 pregnancies but I took a spill a few days before I found out I was prego with this one (was 4-5 wks along when I ate dirt), no damage or injuries to either of us but it really ingrained how dangerous riding can be. So now I'm really debating the riding thing (Only while prego of course).
And By no means will I make my decision from a forum but the stories are still nice to read about and to be able to relate to people is really nice (my family is all non-horsey).
For those curious... The spill was my fault. My mare was moved to a new pasture the night before. I was bareback and over confident. I rode her back into her pasture after a short ride down the driveway and back (She was very alert and fidgety on our short ride but not spooky yet, shoulda been my first clue though), so once we were in the large pasture she immediately wanted to join her herd on the opposite side (About 2 acres away, same pasture though), We battled it out, she submitted, we walked back to the gate so I could dismount and she refused to stand still again, started fidgeting and acting spooky, of course I insisted she stand there and work through it... Well... "bam!" She spooks and bolts across the pasture to her buddies, throwing in a sideways shuffle/crow hop. Which of course unseated me so I decided to bail before she picked up more speed. It was only a matter of time before I would have fallen anyways (I was barely hanging on her, sideways and bareback, plus show sheen = bad combo).
I landed on my butt. Safe and sound luckily. And of course my mare dead stops in her tracks to stare at me like "wth are you doing down there? Did you see that horse eating tree Mom?"
I got back on, rode her back to the tree/next to the gate, made her stand and then dismounted to go ice my tooshy :) I should have been better prepared, prepared her better for new environments and I should have been paying attention to her. There was a few things I`d do differently now but hey it happens to the best of us. First fall in quite a few years too.
Is it sad that I was proud of my fall LoL I'm proud that it didn't wreck my confidence and now that I've fallen off this mare I feel more confident. I think it helped that I am no longer anticipating that first fall. IDK LoL anyone else felt this way?
On the flip side I feel guilty cause I was prego even though I didn't know yet.