I`m currently 19 weeks pregnant with our second child and we`ve discovered that my placenta is low-lying. I was wondering how much this affects my day-to-day exercise. In the first pregnancy, I walked 30 mins briskly most days, and continued this while my first born was young. I have currently been walking the same amount of time almost every day with some mild aerobics thrown in for good measure. My obstetrician has okayed this exercise previously. I don`t see him for a few weeks now and was wondering if the low-lying placenta means I should limit my exercise? Any help would be great, as I don`t want to create any undue risks.