Exercise during and after pregnancy: what the Canadian guideline and the evidence show

Regular physical activity can be an important part of a healthy pregnancy. For many, it can offer benefits throughout pregnancy and into the postpartum period [1]. In Canada, guidelines exist to help pregnant individuals and healthcare providers understand appropriate levels and types of physical activity [1]. Research also explores how exercise may relate to specific outcomes, such as symptoms of anxiety, depression, and urinary incontinence [2, 3].

The 2019 Canadian Guideline for Physical Activity throughout Pregnancy

The 2019 Canadian Guideline for Physical Activity throughout Pregnancy provides recommendations for pregnant individuals and the professionals who care for them [1]. This includes obstetric care providers and exercise professionals [1]. The guideline was developed by reviewing existing literature on maternal, fetal, or neonatal health outcomes related to physical activity during pregnancy [1].

To create the guideline, researchers conducted extensive searches across multiple online databases, looking for studies published up to January 2017 [1]. They included primary studies of any design, except case studies, and focused on materials in English, Spanish, or French [1]. The goal was to evaluate outcomes such as maternal, fetal, or neonatal illness (morbidity), or fetal death (mortality) during and after pregnancy [1].

The quality of the evidence used to form the recommendations was rated using a system called Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology [1]. This system helps to assess how certain the evidence is for a particular recommendation. The guideline's development also followed the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument, a tool for assessing the quality and reporting of clinical practice guidelines [1].

The guideline panel also sought feedback from a wide range of individuals, including obstetric care providers, exercise professionals, researchers, policy organizations, and pregnant and postpartum women [1]. This ensures that the recommendations are practical and relevant to those who will use them [1].

The guideline found that the benefits of prenatal physical activity are moderate, and no harms were identified [1]. This means that the overall positive impact, or "net benefit," is expected to be moderate [1]. The panel also concluded that following these recommendations would likely be feasible, acceptable, and fair (equitable) for most people [1]. They also noted that these recommendations would likely require minimal resources from both individuals and the healthcare system [1].

Main Recommendations

The Canadian guideline offers specific advice for physical activity during pregnancy [1].

It recommends that pregnant individuals who do not have contraindications to exercise should accumulate at least 150 minutes of moderate-intensity physical activity each week [1]. This activity should be spread over at least three days per week [1].

The guideline suggests including a variety of physical activities [1]. This includes aerobic exercise, such as brisk walking, swimming, or cycling [1]. It also recommends incorporating resistance training, which can involve using weights, resistance bands, or bodyweight exercises [1].

Pelvic floor muscle training (PFMT) is also recommended daily to help reduce the risk of urinary incontinence [1]. You can learn more about this type of exercise in our piece on pelvic floor muscle training for incontinence and postpartum recovery.

When to Talk to a Healthcare Provider

Before starting or continuing an exercise program during pregnancy, it is important for individuals to discuss their plans with a healthcare provider [1]. The guideline includes a section on contraindications, which are conditions or situations where exercise might not be recommended or might need specific modifications [1]. A healthcare provider can assess an individual's specific health situation to determine if these recommendations are suitable [1].

Understanding Systematic Reviews and Meta-Analyses

The information about prenatal exercise and its relationship to depressive symptoms and urinary incontinence comes from systematic reviews and meta-analyses [2, 3]. These types of studies are considered high-quality evidence in health research because of their rigorous methods.

A systematic review is a comprehensive search for all relevant research studies on a specific topic [2, 3]. Researchers use a clear, predefined method to find, select, and evaluate studies to minimize bias and ensure all available evidence is considered [2, 3].

A meta-analysis is a statistical technique often used within a systematic review [2, 3]. It combines the results from multiple individual studies that investigated the same question [2, 3]. By pooling data from many studies, a meta-analysis can provide a more precise estimate of an effect than any single study alone [2, 3].

When a review states that it found 'moderate' or 'low' quality evidence, this refers to the certainty of the findings [2, 3]. 'Moderate' quality means there is some confidence in the estimate, but it could change with further research [2, 3]. 'Low' quality means the true effect might be substantially different from what the review found [2, 3].

Terms like "standardized mean difference" (SMD) and "odds ratio" (OR) are ways to measure the size of an effect [2, 3]. An SMD shows how much difference there is between groups on a continuous scale (like symptom severity) [2, 3]. An OR indicates the likelihood of an event (like depression or incontinence) happening in one group compared to another [2, 3]. A "95% confidence interval" (CI) shows the range within which the true effect likely lies [2, 3]. If the CI includes 1 for an OR, or 0 for an SMD, it suggests the effect might not be significant [2, 3]. The I2 value indicates how much variation exists between the results of the different studies included in the meta-analysis [2, 3]. A higher I2 means more inconsistency between study results [2, 3].

It is important to remember that these reviews report what was found across many studies in specific populations [2, 3]. They do not guarantee that the same outcome will happen for every individual, nor do they make claims about preventing or treating a condition for any specific person.

Prenatal Exercise and Depressive Symptoms

A systematic review and meta-analysis published in 2018 examined the influence of prenatal exercise on symptoms of depression and anxiety during pregnancy and postpartum [2]. This review included 52 studies with a total of 131,406 participants [2]. The studies included pregnant women who did not have a contraindication to exercise [2]. Researchers looked at different measures of exercise, such as frequency, intensity, duration, and type, and compared outcomes with no exercise or different exercise routines [2].

Findings on Prenatal Depressive Symptoms

The review found 'moderate' quality evidence from randomized controlled trials (RCTs) suggesting that exercise-only interventions were associated with a reduction in the severity of prenatal depressive symptoms [2]. In 13 RCTs involving 1,076 participants, exercise reduced the severity of symptoms with a standardized mean difference (SMD) of -0.38 (95% CI -0.51 to -0.25, I2=10%) [2].

Additionally, the review found that exercise-only interventions were associated with a 67% reduction in the odds of prenatal depression [2]. This was based on 5 RCTs with 683 participants, showing an odds ratio (OR) of 0.33 (95% CI 0.21 to 0.53, I2=0%) compared to no exercise [2].

To achieve at least a moderate effect size in reducing the severity of prenatal depressive symptoms, pregnant individuals needed to accumulate at least 644 MET-minutes per week of exercise [2]. This could be achieved, for example, by doing 150 minutes of moderate-intensity exercise, such as brisk walking, water aerobics, stationary cycling, or resistance training [2].

Findings on Postnatal Depressive Symptoms and Anxiety

The systematic review also examined the impact of prenatal exercise on postpartum depression and anxiety [2]. It found that prenatal exercise did not alter the odds of postpartum depression or the severity of depressive symptoms after birth [2]. Similarly, prenatal exercise did not appear to change anxiety or anxiety symptoms during or following pregnancy [2].

Prenatal Exercise and Urinary Incontinence

Another systematic review and meta-analysis, also published in 2018, investigated the relationships between prenatal physical activity and urinary incontinence (UI) during and following pregnancy [3]. This review included 24 studies with a total of 15,982 women [3]. The studies focused on pregnant women without contraindications to exercise, looking at various types of exercise interventions, either alone or combined with other components [3].

Findings on Urinary Incontinence

The review found 'low' to 'moderate' quality evidence that prenatal pelvic floor muscle training (PFMT), whether done alone or with aerobic exercise, was associated with a decrease in the odds of UI during pregnancy [3]. This was based on 15 randomized controlled trials (RCTs) involving 2,764 women, showing an odds ratio (OR) of 0.50 (95% CI 0.37 to 0.68, I2=60%) [3].

Similarly, the review found that prenatal PFMT was associated with decreased odds of UI in the postpartum period [3]. This was supported by 10 RCTs with 1,682 women, showing an OR of 0.63 (95% CI 0.51 to 0.79, I2=0%) [3].

When the researchers analyzed the data based on whether women were continent (did not experience UI) or incontinent (experienced UI) before the intervention, they found a difference [3]. Exercise was beneficial in helping to prevent the development of UI in women who were continent before pregnancy [3]. However, it was not found to be effective in addressing existing UI in women who were already experiencing incontinence [3].

The review also noted 'low' quality evidence that prenatal exercise had a moderate effect in reducing the severity of UI symptoms during pregnancy [3]. This was based on five RCTs, showing a standardized mean difference (SMD) of -0.54 (95% CI -0.88 to -0.20, I2=64%) [3]. For the period following pregnancy, 'moderate' quality evidence from three RCTs also showed a moderate effect in reducing UI symptom severity, with an SMD of -0.54 (95% CI -0.87 to -0.22, I2=24%) [3].

Limitations of the Research Reviews

It is important to consider the limitations of systematic reviews and meta-analyses when interpreting their findings. These limitations help to understand the scope and certainty of the evidence.

For the review on prenatal exercise and depressive symptoms, the researchers found that only "exercise-only interventions" were associated with a reduction in prenatal depressive symptoms [2]. Interventions that combined exercise with other components did not show the same effect [2]. This suggests that the specific type of intervention matters. Furthermore, while the review found an association with prenatal depressive symptoms, it found that prenatal exercise did not change the odds or severity of postpartum depression, nor did it affect anxiety symptoms during or after pregnancy [2]. This highlights that the benefits observed were specific to prenatal depression and did not extend to other mental health outcomes or the postpartum period in this review [2]. The studies included were also limited to pregnant women without contraindications to exercise, meaning the findings may not apply to individuals with certain health conditions [2].

For the review on prenatal exercise and urinary incontinence, the evidence quality was described as 'low' to 'moderate' [3]. This indicates that there is some uncertainty, and future research might change these findings [3]. A key finding was that exercise was beneficial in helping to prevent UI in women who were continent before pregnancy, but it was not found to be effective in addressing existing UI in women who were already experiencing incontinence [3]. This means that for individuals already experiencing UI, exercise alone, as studied in this review, was not therapeutic [3]. Some of the meta-analyses also showed moderate heterogeneity (I2 values of 60% and 64%), meaning there was some variability in the results across the included studies [3]. This suggests that the effect of exercise might not be entirely consistent across all populations or intervention types [3]. Similar to the depression review, this review focused on pregnant women without contraindications to exercise and studies published in English, Spanish, or French [3].

What this means for you

The Canadian guideline suggests that regular physical activity, including aerobic and resistance training, and daily pelvic floor muscle training, can be a beneficial part of pregnancy for many individuals [1]. Research also suggests that prenatal exercise may be associated with a reduction in the severity and odds of prenatal depressive symptoms [2]. Additionally, prenatal exercise, particularly pelvic floor muscle training, may be associated with reduced odds and severity of urinary incontinence during and after pregnancy, especially for those who were continent before pregnancy [3]. However, exercise was not found to be effective in addressing existing urinary incontinence in those who were already experiencing it [3].

Before starting or making changes to your exercise routine during pregnancy, it is important to speak with a healthcare provider [1]. They can assess your individual health situation and help determine the most appropriate and safe activities for you [1]. A licensed physiotherapist can provide a personalized assessment and guidance on exercise during and after pregnancy, including specific recommendations for pelvic floor muscle training and managing conditions like pregnancy and postpartum back and pelvic pain.

If you are looking for a physiotherapist, you can search for pelvic floor physiotherapy in Calgary or other areas. You can also verify a professional's registration through their provincial regulatory college — in Alberta, that is the College of Physiotherapists of Alberta [4]. The Canadian Physiotherapy Association is a national professional association rather than a regulator, and it is a useful starting point for understanding what physiotherapists do and how the profession is organised across the country [5].