The fitness industry has traditionally classified pregnant women as a ‘special population’. As we all know, pregnancy is a common and normal occurrence that simply requires your instructor or personal trainer to have additional, more in-depth knowledge. As the cliché goes, pregnancy is not a disease but a condition that warrants specific, appropriate advice.

One of the first things to consider is whether you are new to exercise or a regular exerciser. This can make a substantial difference in:

1. the advice given relative to what exercise you should do i.e. how much and how intense, and

2. your mental attitude to exercise. If you exercise regularly, you’re likely to be more committed and motivated to have adopted exercise as part of your lifestyle. You may therefore be more inclined to question why you should not continue on in the same vein, particularly where there are no problems and you feel fine.

As a new exerciser, you may be coming to exercise at this point because you think it will help improve yours and your baby’s health and make labour easier. What you may not fully appreciate is the effect that the demands of exercise and pregnancy will have on your body, in addition to the normal changes of pregnancy. You may be more likely to lapse if not treated with care, empathy and a sensitivity that comes from knowledge of physical and psychological changes that occur during pregnancy.

In sourcing a good personal trainer for you during this time, ask your instructor if they have had any training in pre/post-natal care for clients.The reason being, that having a pregnant woman turning up to a class, or a female client becoming pregnant during their fitness career is inevitable. It is likely to happen sooner rather than later and is a situation for which all instructors should be prepared.

The American College of Obstetricians and Gynaecologists (ACOG) is the leading body on exercise during pregnancy. Their 2002 guidelines recommend that healthy pregnant women follow the guidelines for exercise, given by the American College of Sports Medicine (ACSM). These guidelines are prescribed for healthy adults but have been modified for the pregnant woman. The modifications are based on certain risks including medical, obstetric and general health as experienced by pregnant females.

Exercise & Pregnancy

They now recommend 30 minutes or more of moderate exercise on most, if not all days of the week. This is subject to whatever special advice has to be given, relative to anything found from the specific assessments undertaken by your trainer/instructor.

Many considered the ACOG’s early recommendations (prior to 2002) a little limited and conservative for pregnant women who were used to exercising. It was noted that higher levels of physical activity were achieved by many women in today’s exercise environments. It was a bit like the ‘220 – age’ (one size fits all) maximum heart rate formula. We know this does not fit across the board and that a person’s individual fitness level can so easily and substantially affect the heart rate at which any individual should train.

The absolute and relative contraindications to aerobic exercise during pregnancy are listed below:

Absolute contraindications:

  • Hemo-dynamically significant heart disease
  • Restrictive lung disease
  • Incompetent cervix / cerclage
  • Multiple gestation at risk for premature labour
  • Persistent second or third-trimester bleeding
  • Placenta previa after 26 weeks of gestation
  • Premature labour during the current pregnancy
  • Ruptured membranes
  • Preeclampsia / pregnancy-induced hypertension

Relative Contraindications:

  • Severe anemia
  • Unevaluated maternal cardiac arrhythmia
  • Chronic bronchitis
  • Poorly controlled type 1 diabetes
  • Extreme morbid obesity
  • Extreme underweight (BMI < 12)
  • History of extremely sedentary lifestyle
  • Intrauterine growth restriction in current pregnancy
  • Poorly controlled hypertension
  • Orthopedic limitations
  • Poorly controlled seizure disorder
  • Poorly controlled hyperthyroidism
  • Heavy smoker

It is also stressed that exercise should be stopped immediately if any of the following occur:

  • Vaginal bleeding
  • Dizziness or feeling faint
  • Increased shortness of breath
  • Chest pain
  • Headache
  • Muscle weakness
  • Calf pain or swelling
  • Uterine contractions
  • Decreased foetal movement
  • Fluid leaking from the vagina

The common concerns arise from the fact that regular sustained exercise is known to raise core temperature, deplete carbohydrate stores, and redistribute blood flow away from organs. It was thought that this might have various adverse effects on foetal development, especially if performed for extended periods of time at high intensities (stated to be more than 55 % of maximum heart rate).

Injuring yourself from the changes your body undertakes throughout pregnancy is also a concern. These changes include maternal posture and centre of gravity, combined with the changes caused by the release of the hormone relaxin. Relaxin aids the birth process by causing a softening and lengthening of the cervix and the pubic symphysis. It is also thought to play a part in the timing of the birth as it is known to inhibit uterine contractions. Relaxin works by simultaneously reducing collagen production and increasing collagen breakdown.

Exercise & Pregnancy

There is an ever-increasing body of information suggesting that regular exercise can actually protect the foetus. There are cardiovascular, metabolic, thermal, and endocrine changes that happen during pregnancy that are not only accentuated by regular exercise, but also modify the physiological response to exercise. It has been documented (ii), that whereas there are no reports suggesting that regular exercise and pregnancy increases the incidence of maternal and/or foetal injury, there are numerous reports indicating the opposite. They indicate that either beginning or continuing a regimen of regular sustained exercise during pregnancy has several positive and no negative effects on the course and outcome of pregnancy.

We know that pregnancy can affect cardiac output by up to 50% by the middle/end of the second trimester. We also know that as the heart rate of a pregnant woman increases by 10 -20 beats by the third trimester, using heart rate to monitor exercise intensity becomes less appropriate. We should be aware that lying on the back (supine), is not recommended after the first trimester because it is thought to adversely affect venous return and, in turn, cardiac output. The position for abdominal and pelvic floor work therefore needs to be revised to a sitting, kneeling or all fours position.

The type of abdominal work done also needs consideration. For example, abdominal curls become inappropriate after a certain stage, particularly if they cause doming that results in the linea-alba separation becoming larger than it should. Compression exercises (drawing the navel to spine) will probably be of more benefit.

There are high risk activities, like scuba diving, where the foetus is at risk of decompression sickness. Activities with a higher risk of abdominal trauma, e.g. horse riding and kickboxing among others, are not advised.

From a conditioning viewpoint, there is recent research (iii) which indicates that intensive pelvic floor muscle training whilst pregnant helps prevent urinary incontinence during pregnancy and after delivery.

Raul Artal MD, Professor and Chair of the department of Obstetrics and Gynaecology at the Saint Louis University School of Medicine, and recently appointed to the WHO pregnancy panel, has stated that ‘women can enjoy a much broader range of physical activity than was previously thought’.

All of the principle parties and organizations participating in and promoting health during pregnancy are of the view that for most, exercising during pregnancy is something that should be encouraged. It seems to be more an issue of what should be done, how much is enough and how much is too much? That remains an open question, partially because of the individuality of the human beings involved. If in doubt, stick with low to moderate intensity unless you know you can do more. Some activity can be done every day. As with the non-pregnant population, advice is to try and maintain a good level of general physical activity. As well as classes, advice suggests doing activities that are easily achievable, such as swimming, cycling and, of course, walking. At the end of the day, common sense and feedback from you must prevail!

References: (i) ACOG Committee: Opinion No.267, Obstet Gynaecol 2002: 99, 171-3 (ii) Clapp III: Am J Obstet Gynecol, Volume 173(1).July 1995.2-9 (iii) Siv Mørkved, MSc, PT Kari Bø, PhD, PT Berit Schei, MD, PhD and Kjell Åsmund Salvesen, MD, PhD – Pelvic Floor Muscle Training During Pregnancy to Prevent Urinary Incontinence: A Single-Blind Randomized Controlled Trial Obstet Gynecol2003:101:313-319

Lorna Malcolm Profile

Lorna works as a writer and presenter for Fitness Industry Education. As a former International Faculty member for the Reebok University, Lorna has spent her 25-year career in the fitness industry travelling the globe training instructors and presenting on various fitness concepts.

She is a qualified physiotherapist who currently teaches Pilates as a rehabilitation tool to provide research for article writing in internationally-recognised publications and global websites. As an author, lecturer and regular media fitness pundit, Lorna is one of the UK’s most highly respected and accomplished fitness presenters.

Exercise & Pregnancy