In order to determine if moderate maternal exercise increased uterine activity, a prospective study was done during the last 8 weeks of pregnancy in 17 women. Two forms of exercise were chosen, weight-bearing (running) and non-weight-bearing (stationary bicycle), to study this hypothesis. The results show that with these types of exercise no increase in uterine activity was noted. This is useful information to convey to pregnant patients ready to engage in a physical fitness program.