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EXERCISE DURING PREGNANCY

A Prescription for Improved Maternal/Fetal Well-being

Davenport, Margie H. Ph.D.

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ACSM's Health & Fitness Journal: 9/10 2020 - Volume 24 - Issue 5 - p 10-17
doi: 10.1249/FIT.0000000000000602
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Women are not just small men, but biologically different, and a woman’s life span has events that are women specific, such as menstruation, pregnancy, and menopause. Although each is important in their own right, pregnancy is unique in that events occurring during gestation can have a lifelong effect on the health and wellness of both mother and baby. Over the nine short months of pregnancy, rapid and profound physiological adaptations occur to nearly every system in the body in order to support the growing fetus. The cardiovascular system in particular experiences some of the most pronounced changes, with the mother experiencing an increase in blood volume (~50%), cardiac output (~30%), heart rate (10 to 15 BPM at rest), and heart size (~30%), with a concurrent reduction in arterial resistance (1). With these myriad changes, and the impending birth of a baby, maintaining optimal wellness during pregnancy is paramount for a healthy delivery and for setting a strong foundation of lifelong well-being.

In addition to the many physiological adaptations occurring, women face numerous socioemotional changes both during and after pregnancy, which is a life-altering event for most new mothers. Pregnancy involves a unique and complex mix of emotions, and each woman responds to these in a different manner. In addition to the stress of hoping for a safe and health pregnancy, many women worry about their relationship with the baby, what family support will look like, if they will be a “good” mother, how will this affect family finances, how feasible is a return to work, or will they have to go to work. These unavoidable stressors, along with the numerous hormonal changes occurring during and after pregnancy, all contribute to serious issues like pregnancy-induced and postpartum depression. Therefore, supporting women both physically and emotionally throughout pregnancy is critical to ensuring the health of both mother and fetus and is the springboard toward greater lifetime wellness.

Although the majority of women will have a healthy successful pregnancy, approximately 20% of pregnancies are associated with complications that include elevated blood sugar (i.e., gestational diabetes or GDM) or elevated blood pressure (i.e., gestational hypertension, preeclampsia) (2). Fortunately, these conditions typically resolve shortly after delivery; however, they do carry lifelong health risks to both mother and baby. Hypertensive disorders of pregnancy are now recognized as risk factors as strong as smoking for the lifelong development of cardiovascular disease, and women with a previous history of GDM have more than a seven-fold increased risk of developing type 2 diabetes compared with those having a normoglycemic pregnancy (3,4). During pregnancy, the abrupt change in lifestyle, lack of sleep, and increased stress can be overwhelming. A mother’s mental health during and following pregnancy also may be affected, with approximately 13% of women diagnosed with clinical depression during pregnancy, and many more experiencing depressive symptoms, including feelings of sadness, irritability, difficulty sleeping, or loss of appetite (5). There are many effective medications available to manage depression, blood pressure, and blood sugars in nonpregnant populations. However, some women have concerns regarding the potential effect of these medications on the fetus even if they are prescribed, and psychotherapy to treat depression can be costly and difficult to access (6,7). Adjunct evidence-based prevention and treatment to improve the health and well-being of pregnant women are critically needed, although women should be cautious about using unproven therapies.

Exercise, or physical activity (PA), is established as a critical component of health across the life span, yet only recently have we begun to realize the powerful influence of prenatal exercise for optimizing the health of two generations, the mother and the to-be-born child. Traditionally, women were told to rest and relax when they became pregnant. However, this changed in 1985 with the publication of the first set of guidelines for exercise during pregnancy by the American College of Obstetricians and Gynecologists (ACOG) (8). These guidelines were rapidly followed by the development of similar recommendations in Spain, Canada, Norway, Japan, Australia, France, Denmark, the United Kingdom, and many other countries around the world (9). Since then, empirical evidence supporting the safety and benefits of prenatal exercise has grown significantly, and global guidelines now recommend engaging in at least 150 minutes of moderate-intensity PA spread over three or more days of the week (see Figure). Indeed, our current view of prenatal PA has shifted away from focusing on the potential risks of exercise, toward prescribing exercise to improve maternal–fetal health (11,12).

Figure
Figure:
Infographic of the benefits of prenatal exercise on maternal/fetal health. Reproduced with permission (10).

Recent data demonstrate that PA during pregnancy decreases the odds of having major pregnancy complications (gestational diabetes mellitus, preeclampsia, gestational hypertension, delivering a large baby) by approximately 40% and decreases the odds of developing depression by nearly 70% (2,13–15). Interventions to prevent these complications may also reduce the odds of developing chronic diseases, including cardiovascular disease, obesity, and diabetes in both mother and baby. This evidence supporting PA during pregnancy also indicates no increased risk of having a miscarriage, small baby, or preterm birth related to the exercise (14–16). Based on the dose–response curves of randomized controlled trials of exercise compared with no exercise, the recommendation of 150 minutes/week of moderate-intensity PA is associated with at least a 25% reduction in the odds of developing each of preeclampsia, gestational hypertension, gestational diabetes, and excessive weight gain and reduces the severity of depressive symptoms (2,13,17). This 150 minutes/week threshold parallels the majority of prenatal guidelines around the world. We now have the strongest empirical evidence to date clearly demonstrating the safety and benefits of being physically active throughout pregnancy for both mother and baby.

Recent data demonstrate that PA during pregnancy decreases the odds of having major pregnancy complications (gestational diabetes mellitus, preeclampsia, gestational hypertension, delivering a large baby) by approximately 40% and decreases the odds of developing depression by nearly 70% (2,13–15). Interventions to prevent these complications may also reduce the odds of developing chronic diseases, including cardiovascular disease, obesity, and diabetes in both mother and baby.

Yet, despite compelling evidence, only 15% of women in the United States meet current guidelines for PA (18). Lack of time, financial cost, social support, work and family duties, and cultural practices continue to prevent many women from taking part in PA while pregnant (19). Many women also are reluctant to be physically active due to fatigue or feeling unwell, or for some women, fear for the safety of their fetus. However, these fears can be alleviated by recent, comprehensive reviews of the literature that have shown that exercise within the scope of current guidelines confers significant physical and psychological benefits, without evidence of harm to either mother or baby. Exercise professionals are ideally positioned to empower women from all socioeconomic and cultural backgrounds to engage in PA throughout their pregnancy. Indeed, there should be a focus on the risks of not being physically active during pregnancy, as those tend to present more concern than for being active. This is also an important time to place a focus on the social, emotional, and spiritual aspects of wellness, as pregnancy is joyous for many, but also can be very stressful for most. Messaging should emphasize that prenatal PA can be a simple, low-cost therapy to reduce the risk of developing pregnancy complications and can improve many other aspects of wellness. For instance, including friends, a partner, or other children in a bout of exercise can build social and emotional support, which is so important during pregnancy. An exercise professional can offer group exercise classes that include both pre- and postnatal moms, dads, and even other family members. Being active, especially in nature, releases endorphins that can boost your mood. Encourage walking in the woods, gardening, or playing at a park to reduce stress and revitalize feelings of well-being. Practicing mindfulness and being present and aware of one’s thoughts and emotions during PA, including walking, yoga, or tai chi can encourage further feelings of well-being, reduce stress, and allow time for reflection and focus, for example, leading a walking activity while coaching clients through mindful breathing techniques. Finally, emphasizing that any amount of PA is beneficial, i.e., “some is better than none”; thus, incorporating even minimal amounts of PA is a good thing. In fact, a brisk walk for just 10 minutes per day can reduce the odds of developing preeclampsia by 25% (2), and increasing to just 15 total minutes per day has the same positive effect on the development of gestational hypertension and excessive weight gain during pregnancy (2,17).

Being active, especially in nature, releases endorphins that can boost your mood. Encourage walking in the woods, gardening, or playing at a park to reduce stress and revitalize feelings of well-being. Practicing mindfulness and being present and aware of one’s thoughts and emotions during PA, including walking, yoga, or tai chi can encourage further feelings of well-being, reduce stress, and allow time for reflection and focus, for example, leading a walking activity while coaching clients through mindful breathing techniques.

When prescribing exercise for the pregnant woman, it is important to recognize that many women can feel isolated or feel a lack of emotional support, which makes initiating exercise that much more difficult. Depression affects approximately 13% of pregnant women, and prenatal depression strongly predicts postpartum depression (5). Depression and anxiety are associated with reduced self-care, preterm labor, and low birth weight, as well as compromised caregiving and bonding with the infant after delivery. However, data show as much as a 67% reduction in the odds of developing depression in women who exercise during pregnancy (13). Even in women not diagnosed with clinical depression, exercise can substantially reduce the severity of depressive symptoms. Although it is not clear whether prenatal exercise can reduce the odds of developing postpartum depression, significant mental health benefits have been observed when women resume exercise in the postpartum period after recovery from delivery (20). Further, group exercise can provide an extra level of motivation, as you are accountable to others, while also increasing valuable social time. Socialization with other women, even the opportunity to interact with exercise leaders or personal trainers, can provide women with the social and emotional support that is critical to positive mental health and overall wellness during pregnancy.

IS THERE A TIME WHEN IT IS NOT SAFE TO EXERCISE DURING PREGNANCY?

Although most women benefit from exercise during pregnancy, there are several medical conditions (“contraindications”) where moderate- to vigorous-intensity PA (MVPA) may adversely affect the health of the mother and/or fetus (21). Ensuring pregnant women are being followed by a medical professional is critical to identifying these conditions. Although these situations are uncommon, they do occur; therefore, specific cautions are warranted when prescribing exercise, and under certain circumstances, exercise should be avoided. An absolute contraindication is a condition where MVPA should be avoided because of an elevated risk of adverse events for either the mother or the fetus. Absolute contraindications may vary between specific guidelines (ACSM, ACOG, CSEP/SOGC, etc.) but most often include serious pregnancy complications such as preeclampsia and intrauterine growth restriction, as well as pre-existing cardiovascular or respiratory diseases (see Table 1) (9). However, it should be stressed that even in these scenarios, activities of daily living may be encouraged as directed by their health care provider. By contrast, relative contraindications warrant a discussion between the pregnant patient and her obstetric health care provider to determine the potential risks and benefits of PA during pregnancy. Conditions such as mild respiratory disorders or symptomatic eating disorders may warrant a reduction in the intensity, duration and/or volume of activity, or avoidance of MVPA, depending on individual risk (21). The development of contraindications can be associated with increased rates of depression and anxiety in pregnant women, which of course presents its own paradox, because the PA typically is what reduces these very same conditions as part of increased wellness. Therefore, it is especially important to care for the mental health and well-being of women who are restricted from activity during pregnancy. Encouraging regular social contact with friends and family and promoting the continuation of light activities of daily living, including such as light-intensity walking, cooking, cleaning, and other activities (as recommended by their health care provider), will support the social, emotional, and spiritual health of pregnant women. In addition to PA, other components of a healthy lifestyle are encouraged. These include adequate and quality sleep and nutrition, as well as avoidance of smoking, alcohol, and all forms of cannabis use (22–25). A savvy exercise professional can create or refer to non-PA workshops, such as healthy cooking, healthy food shopping, and planning for life with a newborn.

TABLE 1
TABLE 1:
Absolute and Relative Contraindications for Physical Activity during Pregnancy from Three Guideline Documents (Reprinted with Permission) (9)

In addition to the assessment of relative and absolute contraindications to exercise, during pregnancy, there are types of exercise where additional caution is also warranted. First, women are recommended to avoid activities with a high risk of physical contact or falling. This may include horseback riding, downhill skiing, riding a nonstationary bike, playing soccer, hockey, or other team sports. Although there is some protection of the fetus through the uterus and amniotic fluid, direct trauma to the abdomen can cause harm to the fetus through loss of amniotic fluid, placental abruption, and or premature labor. Second, there is limited evidence regarding the safety of pregnant women exercising in excessive heat (especially with high humidity such as hot yoga) because of an elevated risk of dehydration. Instead, exercise is recommended to be performed under cooler conditions such as in air conditioning or by avoiding the midday heat by exercising in the shade or in the early morning or evening. Other activities such as scuba diving and high altitude exercise (for those living at sea level) are not recommended (11,12,26).

There also are reasons for pregnant women to stop PA and speak to a health care provider, such as the onset of persistent excessive shortness of breath, severe chest pain, regular and painful uterine contractions, vaginal bleeding, persistent loss of fluid from the vagina, and persistent dizziness or faintness that does not resolve upon rest. These signs and symptoms can represent the initiation of labor or be a symptom of a clinically relevant complication. In these cases, women should cease exercise and seek medical attention.

ENCOURAGING PA DURING PREGNANCY AS PART OF THE WELLNESS CONTINUUM

For decades, women who were not physically active before pregnancy were discouraged from starting after becoming pregnant. This misconception has been debunked by recent studies demonstrating that women who were not active before pregnancy can derive clinically meaningful benefits by beginning to engage in regular PA after conception, even at levels well below current recommendations. Counseling women to start with a low intensity and duration of exercise and taking small steps toward increasing PA is recommended. From getting off the bus a stop early, parking the car farther away, or taking a short evening walk are all great ways to encourage a physically active lifestyle. For those women experiencing back pain or aching joints, water exercise can be a quick and easy way to find relief while getting a great workout. Doing these same activities with others, friends, family, or fellow gym members, also can improve the social, emotional, and spiritual aspects of wellness, which in turn decreases symptoms or risk for pregnancy-related depression and anxiety (Table 2). Walking remains a simple, low-cost mode of exercise and something that every exercise professional should promote. For example, for women who are inactive at conception, encouraging as little as 5 to 10 minutes of moderate walking is a great way to start. If possible, gradually increasing this 1 to 2 minutes per week as pregnancy progresses, even up to 150 minutes per week, will provide even greater benefits to both the mother and fetus. For those who find walking too uncomfortable or difficult, water-based exercises, where available, can be a great alternative.

TABLE 2
TABLE 2:
Other Dimensions of Wellness

Women who were active before pregnancy can continue to be active during pregnancy; however, their activities may need to be adapted. Women who wish to substantially exceed current guidelines (e.g., vigorous and or long duration exercise) should do so in consultation with their health care provider, as there is limited empirical evidence to guide global recommendations for highly active women. Heart rate zones for pregnancy have been developed to allow women to monitor their exercise intensity (11), and alternatively, the “talk test” is a simple way to determine whether exercise intensity is too high, as women should be able to carry on a conversation during moderate-intensity exercise (26).

Historically, women with certain conditions, including preeclampsia or intrauterine growth restriction, were prescribed bed rest with the goal of improving maternal and fetal health outcomes. However, this practice is no longer recommended as empirical evidence now suggests that bed rest induces negative effects on maternal health such as anxiety, depression, muscle atrophy, bone loss, venous thromboembolism, and gestational diabetes. Fetal outcomes are not improved, and some evidence suggests that earlier delivery may occur (27).

Historically, women with certain conditions, including preeclampsia or intrauterine growth restriction, were prescribed bed rest with the goal of improving maternal and fetal health outcomes. However, this practice is no longer recommended as empirical evidence now suggests that bed rest induces negative effects on maternal health such as anxiety, depression, muscle atrophy, bone loss, venous thromboembolism, and gestational diabetes. Fetal outcomes are not improved, and some evidence suggests that earlier delivery may occur (27).

Summary

As exercise and health professionals, it’s important to consider a woman’s physical, mental, social, and spiritual health when prescribing exercise. Health and fitness professionals can encourage women during this period to be active and to include other areas of wellness by inviting friends to be active with them, or practicing mindfulness during PA, or joining group exercise session for increased social interactions. During pregnancy, there will be days where a woman feels tired or unwell, encouraging adequate rest and sleep to ensure recovery is as important as encouraging a resumption of activity after recovery. Consider the individual’s goal, whether it be disease prevention, stress reduction, or mood enhancement, in the design of an exercise plan or in making recommendations regarding PA. Although prescribing exercise during pregnancy requires additional considerations beyond a non-pregnant women, such as time constraints, fatigue, and caring for other children, it is possible to develop effective strategies that increase PA while at the same time improving different aspects of wellness, particularly socio-emotional well-being. And all of these can occur with as little as 10 minutes a day of PA!

BRIDGING THE GAP

Extensive evidence now supports the safety and benefits of prenatal PA to support the health and wellness of pregnant women. Therefore, it is critical that women and exercise professionals shift their individual and collective perspective of prenatal PA away from the potential risks of exercise, and instead realize that an effective exercise prescription can improve health, with subsequent benefits to many other dimensions of wellness. In fact, it may be just as important to consider the many risks of not being physically active during pregnancy.

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    Keywords:

    Exercise; Guidelines; Pregnancy; Prenatal; Physical Activity

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