All of my mares are under saddle and they've all had foals. The only time I wouldn't ride a broodie is right before and after she's foaled. The rest of the time, I expect them to behave like any other horse I ride. I will make exceptions for them if they have a foal at side, and I'll be sure to make sure the foal can keep up or is where the mare can see him at all times but if I want to ride, I go ride. Once the foal is weaned, I give the mare a couple of weeks off to dry up and let the hormones settle, and then it's back to work.