In previous generations, pregnancy was often seen more as an illness than a state of being and the mother to be was treated like an invalid having to cease all normal activity and function. Times have certainly changed and now women continue on, relatively normally and usually with minimal disruption to your lives. As pregnant women you will continue to work, run the household and remain active and healthy.

There has been a lot of confusion in the past about exercise in pregnancy and what is considered safe. Over the last 30 years extensive research has been undertaken, the results of which have dispelled some of the myths concerning exercise in pregnancy. In addition to this, in January 2002 the American College of Obstetricians and Gynaecologists (ACOG) new recommendations for exercise in pregnancy.

While pregnancy is not a time to embark on achieving momentous fitness goals, if you are already fit and active and have no significant medical problems, there is no reason why you can’t maintain your level of activity throughout pregnancy without harm. Some minor modifications will need to be made as you progress through your pregnancy but generally you can continue on with what is normal to you. On the other hand, if you are just starting an exercise programme during pregnancy, you should progress slowly through your new regime.

The general guidelines to adhere to when exercising in pregnancy are:

• In the absence of significant medical problems, pregnant women are encouraged to engage in 30 minutes or more of moderate exercise a day, on most, if not all, days of the week
• During the second and third trimesters, avoid exercise that involves laying flat on your back as blood flow to the womb will be restricted
• Avoid exercise in warm/humid conditions (there is more information on how the body deals with changes in temperature in the article detailing safety issues to consider when exercising during pregnancy)
• Remain adequately hydrated
• Avoid activities that involve physical contact or danger of falling
• Scuba diving should be avoided at all stages of pregnancy as should exertion over altitudes of 2000 metres
• Know your limits – work within your range (to determine how hard you should be working read the article on using heart rate to determine how hard you’re working)
• Choose something that you are going to enjoy!

EXERCISE IN PREGNANCY – HOW HARD CAN I WORK WITHOUT HARMING BABY?

Probably the two greatest areas for concern that I hear from women who are contemplating a pre-natal exercise programme are:

• I’ve been advised to keep my heart rate at 140bpm or below
• Will I risk overheating the baby while I’m exercising

Using Heart Rate to Determine How Hard You’re Working

Before pregnancy one of the easiest ways you will have been instructed to monitor your exercise intensity is by checking your heart rate during a session (either manually or with a heart rate monitor). However, when you become pregnant this all changes and heart rate is no longer a good predictor of how hard you are working.

From the moment you become pregnant physiological changes start occurring. In fact in early pregnancy changes to your circulatory system mean that you heart rate is elevated even at rest. So when you are exercising you will find that your heart rate is elevated well out of proportion to your level of exertion.

On the flip side, in late pregnancy (30 weeks plus) because of changes in your blood volume you’re going to struggle to get your heart rate up to what you think it should be, unless you’re working extremely hard.

So while heart rate is not an ideal indicator of how hard you are working how can you monitor yourself? Throughout pregnancy a more reliable measure to use is the BORG Scale of Perceived Exertion. Using the BORG scale you rate your perception of exertion on a scale of 0 to 20. I like to simplify this further by applying the same principle but by using the talk test as follows:

When engaged in aerobic activity while pregnant it is recommended that you work in and around zone 5 (i.e. conversation requires some effort), so you should still be able to speak but you’ll be a little breathless. It’s important to conduct this self check throughout your exercise session to ensure you’re doing enough but not overdoing it.

Body Temperature and Sweating

The other area which often raises concern and requires clarification is that of the risk of baby overheating whilst you are exercising. Have you noticed how incredibly clever the human body is? This is undoubtedly the case when it comes to body temperature and sweating.

Because both pregnancy and regular exercise generate extra heat you would assume that exercise and pregnancy combined would have a cumulative effect when it comes to body temperature. Wrong! While a women’s basal temperature (that taken immediately upon waking) remains raised for the first 20 weeks of pregnancy, once you’re up and about body temperature falls. The good news is that throughout pregnancy the body makes many adaptations to pregnancy and as a result you have an increased ability to get rid of heat through the skin and lungs.

The even better news is that while the effect of exercise and pregnancy on body temperature are additive, so too are the effects of pregnancy and exercise when it comes to a women’s ability to get rid of excess heat. In fact because of the physiological changes, a woman who exercises regularly in pregnancy can deal much more effectively with heat stress than one who doesn’t.

So, assuming you are properly hydrated and are training in acceptable workout conditions a significant increase in body temperature whilst exercising in pregnancy is relatively low.

WHEN IT’S NOT SAFE TO EXERCISE

In accordance with the 2002 ACOG guidelines the following considerations need to be given prior to commencing an exercise programme in pregnancy.

Women with the following conditions should avoid aerobic exercise during pregnancy:

• Significant heart disease
• Restrictive lung disease
• An incompetent cervix or cervical suture during pregnancy
• Twins/triplets at risk for premature labour
• Persistent second or third trimester bleeding
• Placenta praevia after 26 weeks of gestation
• Premature labour during the current pregnancy
• Ruptured membranes
• Pre-eclampsia/pregnancy induced hypertension

Women with the following conditions should always seek medical advice before undertaking aerobic exercise during pregnancy:

• Severe anaemia
• Maternal cardiac arrhythmia
• Chronic bronchitis
• Poorly controlled Type 1 diabetes
• Morbid obesity
• Extremely underweight
• A very sedentary lifestyle
• Intrauterine growth restriction in current pregnancy
• Poorly controlled high blood pressure
• Orthopaedic limitations
• Poorly controlled epilepsy
• Poorly controlled hyperthyroidism
• Heavy smoking

Warning signs to stop exercising and call your doctor:

• Calf pain or swelling
• Chest pain
• Decreased fetal movement
• Headache
• Leakage of amniotic fluid
• Preterm labour
• Vaginal bleeding
• Uterine contractions
• Deep, severe pubic or back pain
• Unusual breathlessness
• Palpitations or unusually slow heart beat
• Lower abdominal pain or cramping

Always consult a registered fitness professional before starting on an exercise programme. Consider using a personal trainer to work with you, they will assess your specific needs and physiological requirements and tailor an exercise programme to suit.

Helen Wrightson is a registered personal trainer with a particular interest in training pre and post-natal women. Helen is available for both gym based and private training sessions and can be contacted on 0272 835575 or by email on gpe@xtra.co.nz This e-mail address is being protected from spambots. You need JavaScript enabled to view it .