INTRODUCTION
Physical inactivity is one of the most important modifiable risk factors in the general population for non-communicable diseases, which include hypertension, diabetes, stroke, and certain cancers such as breast and colon cancer (WHO 2018). It has also been identified as the fourth leading cause of global mortality by the World Health Organisation (WHO), contributing to 6% of deaths globally.
The prevalence of insufficient physical activity in 2016 was twice as high in high-income countries than in low-income countries (Guthold et al. 2018). This was mainly due to rapid urbanisation and the development of modern technology, especially in transportation systems (Sallis et al. 2016). In the same year, the global age-standardised prevalence of insufficient physical activity was 27.5%, with the prevalence among women exceeding that among men by more than 8% (Guthold et al. 2018). The highest prevalence of insufficient physical activity among women was in Latin America and the Caribbean, followed by South Asia, whereas the lowest prevalence was among men was in Oceania and East and Southeast Asia, followed by sub-Saharan Africa (Guthold et al. 2018).
Insufficient activity is a worrying trend especially among women because in pregnancy, it has been associated with an increased risk of gestational diabetes and hypertensive disorders (Barakat et al. 2016; Rogozinska et al. 2017; Russo et al. 2015; University of Oxford Physical Activity and Pregnancy Study Group 2016; Yin et al. 2014). The WHO recommends that healthy pregnant women be involved in at least 150 minutes of moderate- to vigorous-intensity activity in a week (WHO 2020). Lack of exercise in pregnancy has also been associated with increased gestational weight gain, which may lead to poor maternal and perinatal outcomes (Renault et al. 2014; Rogozinska et al. 2017; University of Oxford Physical Activity and Pregnancy Study Group 2016). Although the health benefits of physical activity in pregnancy have been discussed in detail in previous studies, the level of physical inactivity in pregnancy remains relatively high. Pregnancy could mark the onset of some healthy behavioural changes, such as quitting smoking and restricting alcohol intake, but it also may be a barrier to being active due to the associated physiological and emotional changes (Barakat et al. 2015), which explains why pregnant women tend to lead a sedentary lifestyle. Furthermore, promoting physical activity in pregnancy remains a challenge, especially when the barriers and motivators are not well explored and understood.
Identifying the factors associated with physical activity in pregnancy is crucial for policymakers to review, plan and implement appropriate interventional programmes and manage this particularly vulnerable group. This study aimed to systematically review previous literature and identify the factors that positively and negatively affect physical activity in pregnancy.
MATERIALS AND METHODS
Search Strategy and Article Selection
Article searching was performed in Pub-Med and Ovid the using keywords: (“pregnant women” OR “pregnant lad*” OR “pregnant mother*”) AND (“physical activity*” OR exercise*) AND (factor* OR determinant* OR predictor* OR barrier* OR motivator* OR enabler*). The searches found 248 articles published between 2014 and 2019 in Pub-Med, and 299 in Ovid. The inclusion criteria were original research and studies on factors influencing physical activity among pregnant women. The exclusion criteria were reviews, descriptive studies and non-English articles. After applying the inclusion and exclusion criteria, 16 articles remained for review. The article selection process was summarised in Figure 1.
Quality Assessment and Data Extraction
The quality of each article was assessed using the Mixed Methods Assessment Tool (MMAT) 2018 (Hong et al. 2018). The MMAT was chosen since this review involved the assessment of quantitative, qualitative and mixed-methods studies. This process was performed by two independent authors. Any disagreement between these two authors was resolved by consulting a third author. Important information such as the study location and authors, sample size, study design, study tools, and outcomes of the selected studies was extracted and presented in the table of study characteristics.
RESULTS
Quality of Reviewed Articles
Most of the articles reviewed met the study criteria set in the MMAT, as listed in Table 1, for both qualitative and quantitative studies. However, eight out of the 11 quantitative studies did not represent the target population because most of these studies used convenience sampling instead of random sampling to select their respondents (Flannery et al. 2018; Hoodbhoy et al. 2018; Mullan et al. 2016; Newham et al. 2016; Rauff & Downs 2018; Richardsen et al. 2016). All three qualitative studies met all the quality criteria of a qualitative study set by the MMAT.
Characteristics of Reviewed Articles
A total of 16 studies were eligible for appraisal in this systematic review, as presented in Table 2. Three were qualitative, and the rest were quantitative. Among the quantitative studies, 11 were cross-sectional studies, and the remaining two were cohort studies.
One of the studies was conducted in multiple countries (China and Australia), and the remaining studies were each conducted in a single country. Five studies surveyed populations in European countries: Germany, Netherlands, Ireland, Norway, and the United Kingdom. Three were from Australia, two were from Taiwan, and one each were from the United States of America, Brazil, Iran, Pakistan, and South Africa. The sample size ranged from 61 to 1,279. The smallest sample sizes were from qualitative studies, and the highest sample size was from a cross-sectional study.
Motivators of Physical Activity in Pregnancy
The factors that positively influenced the physical activity level among pregnant women in these studies were capable of managing their exercise participation (Guelfi et al. 2015), strongly valuing the benefit of exercise (Guelfi et al. 2015), not working (Lee et al. 2016), enjoying the physical activity (Bauer et al. 2018; Merkx et al. 2017), having normal or high body weight (De Jersey et al. 2017; Rauff & Downs 2018), burning fat (Bauer et al. 2018; Muzigaba et al. 2014), having to do household chores (Hoodbhoy et al. 2018), earlier trimester (Newham et al. 2016; Rauff & Downs 2018), later trimester (Tung et al. 2014), intention for physical activity (De Jersey et al. 2017; Mullan et al. 2016), pre-pregnancy exercise (Tung et al. 2014), and having exercise as a habit (Mullan et al. 2016; Nascimento et al. 2015). Additionally, some maternal characteristics were identified as motivators: older maternal age (Bahadoran & Mohamadirizi 2015), higher parity (Bahadoran & Mohamadirizi 2015; Lee et al. 2016), higher education level (Nascimento et al. 2015), higher economic status (Bahadoran & Mohamadirizi 2015; Muzigaba et al. 2014), greater general wellbeing (Muzigaba et al. 2014), and the presence of social opportunity and support to engage with physical activity (Flannery et al. 2018).
Barriers to Physical Activity in Pregnancy
Barriers to physical activity or factors hindering pregnant women from being active were older age, (Merkx et al. 2017) having other children (Flannery et al. 2018; Merkx et al. 2017; Richardsen et al. 2016), tiredness (Bauer et al. 2018), overweight (Rauff & Downs 2018; Richardsen et al. 2016), physical discomfort (De Jersey et al. 2017), lower self-efficacy (De Jersey et al. 2017; Van Mulken et al. 2016), lack of time (De Jersey et al. 2017; Muzigaba et al. 2014), lack of knowledge regarding physical activity in pregnancy (De Jersey et al. 2017; Flannery et al. 2018; Hoodbhoy et al. 2018; Van Mulken et al. 2016), lack of support from family and friends (Hoodbhoy et al. 2018; Richardsen et al. 2016; Van Mulken et al. 2016), having physical capability and opportunity (Flannery et al. 2018), physical pain (Flannery et al. 2018; Merkx et al. 2017; Muzigaba et al. 2014), working (Flannery et al. 2018; Tung et al. 2014; Van Mulken et al. 2016), later trimester or gestational age (Bahadoran & Mohamadirizi 2015; Newham et al. 2016; Rauff & Downs 2018), ethnic minority (Richardsen et al. 2016), weight gain (Van Mulken et al. 2016), large body size (Muzigaba et al. 2014), concern for safety of the baby (Van Mulken et al. 2016), primiparity (Lee et al. 2016; Van Mulken et al. 2016), lack of education from medical professionals (Flannery et al. 2018; Van Mulken et al. 2016), lack of trust in medical professionals (Van Mulken et al. 2016), health conditions (Newham et al. 2016), lack of energy (Hoodbhoy et al. 2018; Muzigaba et al. 2014), physically active before pregnancy (Merkx et al. 2017), lack of facilities for physical activity (Hoodbhoy et al. 2018; Muzigaba et al. 2014), being advised to stop physical activity (Merkx et al. 2017), multiparity (Tung et al. 2014) and fear of miscarriage (Van Mulken et al. 2016).
DISCUSSION
In general, women tend to restrict their physical activity during pregnancy, mainly due to perceived safety risks to both themselves and their unborn baby; some may think that rest is more beneficial than exercising and that daily living activities are adequate (Garland 2017; Marshall et al. 2013; Sui & Dodd 2013). However, according to this systematic review, other factors were associated with reduced physical activity in pregnancy.
Whereas enjoyment was one of the most reported motivators of physical activity, the most reported reason for reduced physical activity was lack of knowledge or information among pregnant women regarding physical activity in pregnancy (De Jersey et al. 2017; Flannery et al. 2018; Hoodbhoy et al. 2018; Van Mulken et al. 2016). Certain studies reported that information from health providers was limited and insufficient (Flannery et al. 2018; Van Mulken et al. 2016), which could explain a lack of knowledge, especially regarding the importance of physical activity among these pregnant women. One qualitative study from Australia reported that some of the participants questioned the expertise of general practitioners who advised them to exercise regularly, reflecting a lack of belief and trust towards the general practitioner’s knowledge on this subject.
Social factors such as support from friends and family also played an important role in encouraging pregnant women to be physically active (Bauer et al. 2018; Flannery et al. 2018; Hoodbhoy et al. 2018; Muzigaba et al. 2014; Richardsen et al. 2016; Van Mulken et al. 2016). This may explain why ethnic minority was reported as a barrier to being physically active by Richardsen et al. (2016): ethnic minority people may have a lack of friends and family to support them. This indicated the importance of targeting the whole community instead of only the individual in promoting physical activity in pregnancy. Expectant mothers’ tendency to be active is highly likely to be influenced by the social perception of physical activity surrounding them (Van Mulken et al. 2016). This finding was in line with the socio-ecological model, in which a particular health outcome or behaviour is affected by not only the individual, but also their social surroundings (Özdemir 2013). Other factors in the social category were income, education, and employment status. Higher-income and higher-educated pregnant women were more likely to be physically active (Bahadoran & Mohamadirizi 2015; Muzigaba et al. 2014; Nascimento et al. 2015), although those in the workforce cited work and lack of time as barriers to be physically active (Flannery et al. 2018; Muzigaba et al. 2014).
The built environment was also an important aspect as evidenced by two papers from South Africa and Pakistan, which reported that the availability and affordability of physical activity facilities such as gyms and fitness centres were significant factors in physical activity in pregnancy (Hoodbhoy et al. 2018; Muzigaba et al. 2014). This could be partly due to the cultural values of certain communities in the world, where women are relatively deprived of opportunities and access to appropriate and safe outdoor environments and infrastructure for physical activity. This environmental factor also highlights the importance of urban planning, among others, to increase physical activity levels, especially among women (Althoff et al. 2017; WHO 2018).
Among the non-modifiable factors identified in this review were age and number of living children. However, further research is needed to determine the influence of these two factors since conflicting findings were reported. For instance, Van Mulken et al. (2016) identified primiparity as a barrier whereas Nascimento et al. (2015) identified it as a motivating factor. Later trimester or gestational age was also a significant barrier to physical activity, as reported by four studies (Flannery et al. 2018; Merkx et al. 2017; Richardsen et al. 2016; Tung et al. 2014). This could be due to the physical pain and discomfort associated with physical activity during the later stages of pregnancy (Flannery et al. 2018; Merkx et al. 2015; Muzigaba et al. 2014).
To our knowledge, no systematic review has been conducted on the factors influencing physical activity in pregnancy, especially in recent years using the MMAT 2018 (Hong et al. 2018), a standardised and rigorous method of critically appraising quantitative, qualitative and mixed-methods studies. Therefore, this review’s findings reflect the current situation and may help health professionals and policymakers alike to plan and implement effective physical activity programmes for pregnant women.
The findings of this review came from various countries and different populations, which may provide a broader view and comparison of factors influencing physical activity in pregnancy across the world. However, the operational definitions of physical activity used in these studies varied and therefore may have led to differing interpretations of results and outcomes.
CONCLUSION
Fun and enjoyment was one of the most reported modifiable motivating factors, and lack of knowledge was the most reported barrier to physical activity in pregnancy, raising the need to review the effectiveness of current relevant health education programmes regarding this subject matter. These programmes should be extended and targeted beyond pregnant women themselves for better uptake and acceptance since depending on their surrounding people and social support was highly likely. Further reviews should focus on the type, duration, and intensity of physical activity recommended for pregnant women.
ACKNOWLEDGEMENT
The authors would like to express their gratitude to all individuals who directly or indirectly provided assistance and technical help in completing this review article.