- my iParenting

- quick clicks
- iparenting fitness articles
- iparenting fitness q&a
- community & groups
- research baby names
- prepare a birth plan
- content channels
- ip channel rss feeds
- read birth stories
- read parenting stories
- recommended books
- e-newsletters
- safety recalls
- ip diaries
- ip store
- mom of the month
- dad of the month
- editor's letter
- letters to the editor
From Our Sponsors
- e-newsletters
- Sign up to receive our free weekly e-newsletters
- award-winning products
The iParenting Media Awards program helps parents find the best products for their families.

Expert Q&A
![]() | ||
| By April Underwood Fitness Consultant Playa del Rey, California | ||
My sister is a fitness fanatic and just found out she is pregnant. She was told that she couldn't allow her heartrate to elevate above 150 beats per minute while working out. However, her heartrate usually approaches 200 bpm when exercising. Will this harm the baby? What additional research can she read about this subject? - Laura, Edmond"
Laura, It's good that you are concerned. It's reasonable for you sister to lower her exercise intensity during her pregnancy for several reasons:
#1 When you exercise, your body temperature rises as a result of increased blood volume. Externally your body temperature rises, and also internally. Internally your body temperature is several degrees higher than externally because there isn't a cooling mechanism on the inside that works like the air on your skin outside. Therefore the fetus temperature can rise to unsafe levels.
#2 During any extreme physical activity like exercise, the blood flow shifts from other organ functions to your working muscles, and to the skin to keep you cool, which means the blood flow to the fetus is diverted temporarily. Which is the same reason why when you eat shortly after a meal, digestion stops or slows down. After your exercise you may feel like your food is still sitting in your stomach. That's because it is!
The conclusion to all of this is, that according to the American College of Obstretics and Gynecology, you should not let your heart rate exceed 140 beats per minute. If her doctor told her 150 bpm, it's probably because she's in good physical condition. For someone who is normally sedentary, 140 bpm may be too high. 200 bpm is definitely not a safe range during any stage of pregnancy.
It's also recommended that you pay close attention to the duration of your exercise sessions. 40 minutes is good. If she really likes working out, than twice a day for 40 minutes is better than once a day for 1 hour. She should make sure there is plenty of ventalation to allow her body to cool down properly. Aerobics classes in poorly ventalated rooms are not advisable. Your sister should also drink plenty of water to replace what she's losing during exercise. I would reccommend twice as much as normal if she continues to work out often.
And, MOST IMPORTANT, take the opportunity to remind your sister that the nurturing of a growing baby in your womb takes special care and attention. This is a time to only be concerned with fitness maintenance, and what you need to do in order to allow for a healthy child to grow in your womb. Your concerns are valid, but you may be pleasantly surprised to know that in spite of all of the guidelines that I just gave you, your body will force you to regulate your fitness activities as a natural response to pregnancy. All she needs to do is listen very closely to what her body and baby wants, and not to continue on automatic pilot doing all the things she's normally used to doing."
Related Expert Q&A
More Answers by this Expert
- Can the change in the estrogen level from pregnancy play a part in my knee pain after running?
- If you exercise the Kegel muscles every day, how long would it take to see results? Are there any other methods that work?
- Am I putting my fetus at risk by running in a marathon at 61/2 weeks?
- Are step aerobics okay during pregnancy and if so, for how long (1st, 2nd, 3rd trimester)?
- Are yoga breathing techniques or exercises safe during pregnancy?



