RESEARCH REVIEW: Exercising for 2? Updated guidelines for an active pregnancy

A review of evidence-based research has delivered some highly recommended reading for fitness professionals – comprehensive guidelines on physical activity for pregnant women.

Title: Exercise and pregnancy in recreational and elite athletes: Evidence summary from the IOC, exercise in women planning pregnancy and those who are pregnant.
Author: Drs Bo and colleagues. (Department of Sports Medicine, Oslo, Norway)
Source: British Journal of Sports Medicine. Available free online: bjsm.bmj.com/content/50/10/571.full


Introduction: In a recent tutorial for the Master’s degree in Clinical Exercise Physiology, a student inquired which of the ‘guidelines’ she should follow for exercise prescription for women who are survivors of breast cancer. This was actually a very good question which had resulted from previously providing two different sets of exercise prescription guidelines in the course lecture. One of the guidelines was from Exercise and Sports Science Australia (2009) and the other from the American College of Sports Medicine’s initiative Exercise is Medicine (2014).

I prefaced my answer by reminding the students that their exercise prescriptions must be evidence-based. In case you’re unfamiliar with this term, Sackett defined evidence-based practice (EBP) as ‘the integration of best research evidence with clinical expertise and patient values’. That’s why it is of the utmost importance that we are always abreast of the literature in our area(s) of expertise – to ensure the best outcomes for our clients/patients.

In short, all exercise prescriptions, regardless of whether they are prescribed by a medical doctor, accredited exercise physiologist (AEP) or personal trainer, must be safe and effective. These guidelines (also called position statements), which we follow for exercise prescriptions, are derived by experts from the currently available scientific research. The guidelines will change over time as new research findings become available, particularly with regard to the best outcomes using exercise as medicine/treatment. For example, Exercise and Sports Science Australia released a new position statement in October on exercise for the prevention and management of osteoporosis (clearly an important read for all AEPs, personal trainers and fitness enthusiasts). So, getting back to the question I was asked by my student, both of the guidelines presented were acceptable because they were evidence-based, and if the students were to look closely, they would find that there are only minor, subtle differences between the two guidelines.

Professor Bo and her colleagues have updated the guidelines on physical activity/exercise for women planning to be pregnant or those currently pregnant. The guidelines are quite comprehensive, so we have only addressed a number of the topics in this Research Review. As this is quite a comprehensive set of guidelines, we'll provide an overview in this Research Review on the following selected areas:

Musculoskeletal adaptations to pregnancy: The growth of the uterus results in a change in the centre of gravity, which may result in progressive lumbar lordosis and anterior rotation of the pelvis on the femur – both of which could interfere with certain exercises or performance in specific sports.

Balance with pregnancy: Balance is affected after the first trimester, and this places women at an increased risk of falling (2 to 3-fold higher risk).

Cardiorespiratory adaptations to pregnancy: From the fifth week of gestation, there is a significant alteration to the cardiovascular system as blood flow must be shifted to the foetus. The heart changes structurally, with the internal cavity increasing in size with no commensurate increase in wall thickness. Resting heart rate increases by 15 to 20bpm, and stroke volume (the volume of blood pumped from the left ventricle per beat) increases by approximately 10 per cent in the first trimester.

Thermoregulatory adaptations to pregnancy: The foetal neural tube is developed at around five to six weeks from the last menstrual period: raising body core temperature above 39°C can increase the risk of foetal (neural tube defect) abnormalities.

Exercise at altitude: Given the popularity of altitude training centres here in Australia, we felt it was important to include this information in this review. The theoretical concern with exercise at altitude (the authors admit there are no studies available on pregnant endurance athletes exercising at high altitude, simulated or actual) is that, while pregnant, hypoxia and exercise both decrease blood flow to the uterus, which would result in a decrease in foetal oxygen saturation. The authors therefore advise avoiding high-intensity exercise at altitudes greater than 1,500 to 2,000 metres.

Endurance: In recreational athletes there were no differences in maximal aerobic capacity (VO2max), however in highly conditioned athletes a moderate to high level of exercise during and after pregnancy may lead to an increase in VO2max of 5 to 10 per cent.

Strength training: Light to moderate weight training was reported to generally have no adverse health effects; however, there is scant research available on strenuous strength training in recreational individuals and none on pregnant elite athletes.

Sports and activities to avoid: Sports or activities associated with possible trauma by a collision, or being hit by something (ball, stick, falling) should be avoided. Similarly, sudden decelerations are highlighted (e.g. bobsleigh) and similar concerns would apply to sports with inertial effects (e.g. Olympic Lifts). Also, pregnant women are advised not to scuba dive, as the foetus is not protected from decompression problems and is therefore at risk of malformation and gas embolism.

Fatigue: This is a common complaint throughout pregnancy, affecting approximately 90 per cent of women. It is generally not related to a pathological problem; however, exercising women are advised to get their haemoglobin checked to ensure they are not anaemic.

Gestational weight gain: This is the amount of weight gained from conception to delivery. The authors have provided guidelines, which are based upon their pre-pregnancy BMI (see Table 2 in the full article). For example, a normal weight woman (BMI 18.5 to 24.9kg/m2) should have a weekly weight gain of 0.35 to 0.5kg. Women with twins have a separate recommendation, for example a normal BMI woman would gain 16.8 to 24.5kg during the course of her pregnancy with twins.

Conclusions: This is a comprehensive guideline, a must-read for all active pregnant women, women planning a pregnancy, AEPs and personal trainers.

Pros: Good article which summarises common conditions, illnesses and complaints that may interfere with strenuous exercise and provides recommendations for exercise training. We strongly recommend all women who are pregnant or planning to get pregnant seek their GP’s and/or specialist’s advice with regard to physical activity/exercise.

Given this article is available free online, we advise all women who are pregnant or planning to get pregnant to read this article.

Cons: None.


Associate Professor Mike Climstein, PhD FASMF FACSM FAAESS is one of Australia’s leading Accredited Exercise Physiologists and researchers. mike.climstein@sydney.edu.au

Joe Walsh, MSc is a sport and exercise scientist. As well as working for Charles Darwin and Bond Universities, he is a director of Fitness Clinic in Five Dock, Sydney. fitnessclinic.com.au