Let’s move baby!The American College of Obstetricians and Gynecologists (ACOG) has established guidelines for aerobic exercise during pregnancy and the postpartum period. These advisory instructions are intended to be suitable for all healthy pregnant women, regardless of their basic level of physical fitness.Why should I exercise during pregnancy?The fundamental purpose of exercise during pregnancy is to maintain or improve fitness. Thus, the intensity, frequency, and duration at which exercise is prescribed for a pregnant woman should be adjusted downward.How much is too much?In regards to exercise intensity, due to the natural physiological influences of the cardiovascular system during pregnancy, pregnant exercisers should gage intensity using the “talk test” or rating of perceived exertion (RPE). As the name implies, the “talk test” is conducted to ensure that the woman is exercising at a comfortable intensity in which she can carry on a conversation. If this is not possible, exercise intensity should be reduced. While the “talk test” tends to err on the side of conservatism, it can be very helpful in ensuring that the intensity of an exercise bout is not excessive for a particular individual at a particular moment in time.Pregnant exercisers can also assess exercise intensity using Borg’s scale of perceived exertion. On this scale, which ranges from 6-20 (6 being very, very light and 20 being very, very hard), a rating of 12 to 14 is most appropriate for pregnant exercisers. Individuals may also wish to use rating of perceived exertion in conjunction with the modified version of the age-corrected heart rate target zones established by the SOGC and CSEP, which accounts for the reduction in maximal heart rate reserve that occurs during pregnancy.As far as exercise frequency and duration are concerned, it is suggested that healthy pregnant women, like all healthy individuals, aim to engage in moderate-intensity physical activity for at least 30 minutes a day on most, if not all, days of the week. If you are new to exercise however, gradually increase your physical activity level beginning with 15 minutes of continuous exercise three times a week and progressively increase to 30-minute sessions four times a week.Adjust as needed.Over the course of their pregnancies, most women appear to spontaneously adjust the intensity, duration, and/or frequency of their workouts to appropriate levels (e.g., most women tend to naturally exercise at lower intensities and for shorter durations during the latter stages of pregnancy). A good indicator of an appropriate exercise program is that a pregnant woman should be fully recovered within 15-20 minutes after the workout.Listen to your body.It appears that some exercise activities are more suitable than others for a pregnant woman who is just beginning an exercise program. The most suitable aerobic exercises for the newly exercising pregnant woman are low-impact activities such as walking, swimming, cycling, and independent-action stair climbing. Women accustomed to running prior to pregnancy can safely continue to do so provided they “listen to their bodies.” All factors considered, the most appropriate form of cardio exercise during pregnancy is the one that the woman most enjoys and can safely perform.One size doesn’t necessarily fit all.Although the information presented above addresses both regular exercisers and those who are new to exercise, it is important to remember that the ACOG guidelines are intended to be suitable for healthy pregnant women with no complications. Keep in mind that certain health conditions and/or complications may result in some restrictions or specific modifications for exercise, so always check with your doctor first before beginning or continuing an exercising routine to ensure the safety of the activities for your unique pregnancy.