Should lactating women exercise?

The safety of recreational exercise for lactating mothers has been examined in a prospective, intervention study. Thirty-three women, who were 6-8 weeks postpartum and breast-feeding exclusively were randomly chosen to join either an exercise or a control group. The exercise group took part in a program of aerobic activities averaging 4.5 sessions per week. After 12 weeks, aerobic capacity was significantly higher in the women who had exercised than in the controls, but no differences in body weight, body fatness, energy expenditure, or resting metabolic rate (RMR) were noted. The exercise program had no effect on breast milk output or composition or infant weight gain. This demonstrates that recreational exercise sufficient to improve cardiovascular fitness without substantially altering energy balance does not adversely affect lactation performance.