Time to revisit medical ‘absolute’ and ‘relative’ contraindications.
Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, Women and Children’s Health Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
Dr. Victoria Meah is a CIHR/WCHRI-funded Postdoctoral Fellow at the Program for Pregnancy and Postpartum Health, and British Association of Sport and Exercise Sciences Certified Exercise Practitioner. The published article is part of Victoria’s research investigating integrative cardiovascular regulation during pregnancy under the supervision of Drs. Margie Davenport and Craig Steinback at the University of Alberta.
- The authors identified 10 conditions that should be listed as absolute contraindications to prenatal exercise because there was evidence that engaging in moderate-vigorous physical activity increases the potential risk for harm to either mother or fetus.
- The authors identified 10 conditions that should be listed as relative contraindications to prenatal exercise in which women should remain physically active, but may require modification of intensity, type and duration of activity.
- All pregnant women, with or without contraindications to prenatal exercise, should be encouraged to maintain activities of daily living (i.e. walking or light stretching) to avoid the adverse effects of inactivity (e.g., bedrest) on maternal and infant health.
- Pregnant women who engage in regular moderate-vigorous physical activity (MVPA) derive significant benefits to maternal and fetal health without evidence of harm. Conversely, a sub-set of women with pre-existing conditions or pregnancy-specific complications, known as contraindications, are advised to avoid MVPA due to concerns of adverse pregnancy outcomes. Contraindications to prenatal exercise have been listed in guidelines for over 30 years; however, most are based on expert opinion only and may be outdated in light of new evidence on the wide-ranging benefits of being active during pregnancy.
- The authors systematically searched research databases for studies on physical activity (acute and/or chronic) in pregnant women experiencing contraindications, as diagnosed by a medical professional.
What the researchers found
In 10 conditions, prenatal MVPA was associated with a strong potential for harm to either the mother or fetus. These should be classified as absolute contraindications and MVPA should be avoided. These were:
- severe respiratory disorders (diseases of the airways and other structures of the lungs like COPD, with exercise intolerance),
- severe cardiovascular disorders (including defects or diseases of the heart, its valves or the blood vessels, with exercise intolerance),
- arrhythmias (heart rhythm problems),
- placental abruption (separation of the placenta from the uterus that causes bleeding and/or pain),
- vasa previa (where fetal blood vessels run across the opening of the cervix and are unprotected),
- uncontrolled type 1 diabetes (unpredictable or frequent episodes of low blood sugars),
- intrauterine growth restriction (estimated fetal weight less than 10th percentile),
- active preterm labour,
- severe preeclampsia (high blood pressure, protein in urine and intrauterine growth restriction),
- cervical insufficiency (preterm dilation of the cervix).
In women with absolute contraindications, the risks of prenatal MVPA outweigh the benefits. However, these women should maintain activities of daily living (e.g. walking or light stretching), as the adverse effects of complete activity restriction (bedrest) are well documented.
The authors further identified 10 conditions that should be classified as relative contraindications. This means that regular prenatal MVPA is likely safe, but the intensity, type and duration of activity may need to be modified. These were:
- mild cardiovascular disorders (with exercise tolerance),
- mild respiratory disorders (with exercise tolerance),
- mild preeclampsia (high blood pressure and protein in urine, but without other complications),
- well-controlled type 1 diabetes (no recent episodes of low blood sugars),
- premature rupture of membranes (breaking open of the amniotic sac before labour begins),
- placenta previa after 28 weeks (placenta overlies the opening of the cervix),
- untreated thyroid disease (women without prescribed medication),
- severe and symptomatic eating disorders (shown by inadequate pregnancy weight gain, restrictive or compensatory behaviours or reduced fetal growth),
- undernutrition (chronic low access to food and/or certain nutrients),
- heavy smoking (≥20 cigarettes per day) in the presence of other complications (like high blood pressure or reduced fetal growth).
There were 11 conditions that were previously listed as relative or absolute contraindications but where there was no evidence to support stopping prenatal MVPA. Women with these conditions should be encouraged to meet current prenatal exercise recommendations.
The following conditions should therefore not be considered a contraindication to prenatal exercise:
- chronic or gestational hypertension (high blood pressure diagnosed before or during pregnancy),
- women categorized as obese (BMI ≥30),
- recurrent miscarriage (loss of 3 or more pregnancies before 24 weeks),
- short cervix (diagnosed as <25 mm),
- multiple baby pregnancies (twins, triplets or more),
- epilepsy (treated and no recent history of seizures),
- anemia (haemoglobin level <100 g/L),
- orthopedic limitations,
- a history of extremely sedentary lifestyle,
- a history of spontaneous preterm labour
- a history of intrauterine growth restriction.
The systematic review provides evidence-based support for a number of contraindications to prenatal exercise; however, it also identified conditions that should be downgraded from an ‘absolute’ to a ‘relative’ classification (italicized above) as well as conditions that should not be considered a contraindication and in which MVPA to current guidelines should be recommended. In many cases, previous research was extremely limited; therefore, future research should include women with conditions that are considered contraindications to prenatal exercise to provide better information regarding prenatal physical activity for these groups, as well as their exercise and healthcare providers.
Reference: Meah VL, Davies GA, Davenport MH. Why can’t I exercise during pregnancy? Time to revisit medical ‘absolute’ and ‘relative’ contraindications. Systematic review of evidence of harm and a call to action. Br J Sports Med. 2020.