Pregnant mare... when to stop riding?

Hello all,

I'm sure this has been posted elsewhere but I just didn't do a search so what I would like to know is if you have a mare that is in foal (she's due Aug. 20, 2011) and she hasn't been ridden much over the last year how safe is it to ride her on light trails? Also, at what point should I NOT ride her anymore?

She won't be ridden at much more than a walk/gait but I don't want to harm the foal or her by riding her.

I realize that you can usually ride a horse almost up until they are ready to foal assuming they had been ridden regularly before (almost like a woman being able to work up until her due date depending on the work load) so I'm curious what everyone's opinion was on this subject.

Well, there are a lot of factors. First of all, how old is your mare? And how far along is she now?

Well, as I said in my first post she's due Aug 20th. And she's somewhere around 15.

Light trails should be fine, up til about 2 months before she foals!
My mare had her foal last year at the end of April, and I stopped riding her at the beginning of February. The first reason was because she had sliced her knee out in the pasture and I just didn't want to stress it anymore than it would be. The second reason was that I just felt that stopping 2 - 3 months before foaling is only fair, because the mare will be eating a lot of extra food in anticipation of the foal's birth, and the foal will be taking a lot of her energy, so she won't have much to spare.
When I stopped riding her, though, I still kept her in shape by lunging. It isn't good for your mare to ride her, even if you only ride her once or twice a week, and then 'throw' her out in the pasture/stall until she foals, simply because she needs to have the strength to foal, and then chase around that little foal. When I lunged her, I only did 5 minutes of trotting and the rest walking, and when she was really close (2 weeks), only walking on the lunge line, or in hand.
Depending on the mares attitude and condition, you can still hop on her and walk around bareback up until a few weeks before she is due.
After the foal is born, I would wait a week or two to get back on her. I had to wait a month, but that was because my mare had to get stitches from foaling (the man who delivered the foal pulled when my mare wasn't having contractions) so I had to wait until she had healed up nicely to start her back.

Good luck with your mare's pregnancy and birth, and with your new foal! They are so much fun to play with and train!