Ahh I stand corrected! Couldn’t remember where I was told it but I’ve always thought it was true!Thats not true. Riding is fine from that point of view, its just more that falling off risk on the early stages and then in later stages most people are too big to ride as its not comfortable or you are too heavy for the horse. I know loads of people who rode right up until the baby was born with no issues. I wouldn't personally as I would be worried about falling off but each to their own.
Actually I’ve just checked and it says it can cause placenta abruption but it’s at the riders risk. Knew I’d seen it someone