Joan,
I have had a few mares over the years thet were pregnant. I have always kept
them active at whatever they were used to doing. My own doctor told me that
when I was pregnant, and it made sense to me!
One mare was a trailhorse I rode at least 5 times a week. She did a 6 hour
ride the day she foaled. She did great!
One was a shetland mare, bred to a standard jack, who got so huge I finally
couldn't drive her anymore....She wouldn't fit between the shafts! But that
wasn't until the 10th month.
There were a few others too, all were worked up til the day they foaled,
within reason, and all had no problems. They didn't have much belly to get
rid of after, either.
I would keep riding, don't do a lot of all out running, or really steep up
and downs, she's going to feel awkward and clutzy sometimes, and it'll
gradually get worse. If she starts acting like she's just not enjoying
herself anymore, slack off. But IMO, she will be much healthier and happier
being used than standing around getting fat, lazy, and out of shape.
Good luck.
Julie