During pregnancy, your resting heart rate will rise slightly because the heart is pumping more blood throughout the body than usual. The Merck Manuals online medical library says that, while the normal resting heart rate of a woman of childbearing age is 70 beats per minute, a pregnant woman's resting heart rate should be around 80 to 90. Keeping an eye on your resting heart rate, as well as your heart rate during exercise, is important because it's a key indicator of your health during pregnancy.
Measure your resting heart rate first thing in the morning. To do this, place the tips of your index and middle fingers at the base of your thumb where it meets your wrist. You should feel a strong pulsing sensation. Using a stopwatch to keep track of the time, count the number of beats during a 60-second time period.
Keep an eye on your overall exertion rate while working out. If you find it hard to talk while exercising or you can't catch your breath, slow down. Walk one mile around a track to cool down a bit, then stop.
Measure your active heart rate by placing your middle and index fingers at the base of your thumb for 60 seconds, just as you did when finding your resting heart rate.
Compare your measurement to ideal heart rates for your age group while exercising. Generally, women younger than 20 should hit 140 to 155, women ages 20 to 29 should remain between 135 and 150, women 30 to 39 should stay between 130 and 145, and women older than 40 should be between 125 and 140. Though there are no recommended tweaks to that number for pregnancy, most doctors agree it's best that pregnant women hit the low end of the range for their age group.
Slow down if your heart rate is consistently too high while exercising. Monitor it to make sure it decreases. If your resting heart rate or active heart rate are consistently above average, make sure to tell your doctor.