The impact of physical activity on urinary leakage (UL) has previously been considered, but not in relation to first pregnancy and delivery. The aim of this study was to describe physical activity and urinary leakage before, during and after the first childbirth. The subjects who were invited to participate in the study were taken consecutively from nine maternity clinics in the northwest part of Stockholm County, and the study group included 665 primiparous women. The mean age of the women was 28 (range 17-43) years. The women answered one questionnaire during the 36th gestation week and another 1 year post partum. Physical activity/exercises were classified according to their impact on the pelvic floor, and the women were divided into three groups: high-impact exercise (n=327), low-impact exercise (n=84) and the inactive group (n=254). The results showed a high intensity and frequency of physical activity in the participating primiparous women. Risk factors for UL were symptoms of a dysfunctional pelvic floor and connective tissue disorders and high-impact physical activity before pregnancy, while low-impact activity seemed to promote continence. If urinary leakage was present before pregnancy, it persisted in most women during pregnancy and 1 year post partum.