I have 3 horses & was riding 6 days a week before i found out i was pregnant (didn't find out i was until i was 14weeks gone), my DH put his foot down when he found out i was expecting, no more riding till baby is here. I don't really mind. It's winter and ponies arn't doing as much during these months.
When i was 10weeks gone i fell off badly at high speed from one of my horses, but because i didn't know i was pregnant i just dusted myself down and got back on.
Personally it's not worth the risk...
Because i have my own horses i am still involved in their day to day care - although i don't do any of the lifting etc anymore i suppose i am still at risk of getting kicked. I know it sounds odd but ever since i found out it's as if my horses have sensed to be careful with me, my youngster especially. He's a wild lil bugger at times and is a right handful for my DH but with me he's like a saint (although now i'm getting bigger and slower to move DH pretty much does 99% of the daily horsey duties)