Women without complications during their pregnancies can exercise right up until they deliver. In the best case scenario, a woman should moderately exercise for at least 30 minutes a day for about five or six days a week. (Important to note: There are exceptions and women who have high-risk conditions such as preterm labor, premature rupture of membranes, vaginal bleeding, placenta previa, or preeclampsia will and should be limited by their obstetrician.) Every woman should consult her doctor about her workout regimen and health history in her first trimester.
In the first 12 weeks of pregnancy, most women can continue with their normal exercise routines without changing it up too much. Initially, most women don’t know they’re pregnant so they continue their routine without any thought and therefore modification. In most cases, exercise releases endorphins which alleviate stress and help pregnant women feel much-needed relief and comfort. However sometimes, exercise can cause nausea and sickness; if this is the case, do not push the limits and force yourself. Your body will know when it’s time to start up again.
If you weren’t active before your pregnancy, do not suddenly start exercising a lot. Instead, ease into low-impact activities such as yoga, swimming, or walking. Whereas if you do work out regularly, you can probably afford to push the limits a bit because you’re starting at a more advanced fitness level. Please check out several other safe but effective exercises for pregnant women on page 78 of The Mommy Docs’ Ultimate Guide To Pregnancy and Birth.
However no matter your capabilities, the best and safest way to monitor yourself is keeping track of your heart rate. You can find a decently priced heart rate monitor at any sporting good store. You should be able to maintain your heat beat at less than 140 beats per minute. If you aren’t able to converse comfortably, you are pushing the boundary. Women are often taken aback with how easy it is to exceed 140 beats per minute, but it’s important to note that your resting heart rate is already higher due to the pregnancy.
Keeping track of your heart rate at all times, but especially during exercise, is vital because when you’re working out hard the blood that’s normally in the uterus and around the growing baby is shot out to the muscles in your body. When your heart rate is above 140, your muscles receive the majority of both, oxygen and blood. (This isn’t harmful to the baby once in a while, but can be very detrimental for extended periods of time because if decrease in oxygen flow.)