CONCLUSION: Most women reduced their physical activity level during the first 20 weeks of pregnancy compared with their level of activity during the year prior to pregnancy, particularly for sports and exercise, although a small proportion of women in this study actually increased their activity in this area during early pregnancy. Participation in sports and exercise activity during pregnancy is potentially modifiable and could favorably impact perinatal health and maternal post-partum weight. The results of this study suggests that pregnancy is an event that leads to a decrease in physical activity.