At some point early in our careers as physical therapists, we will see patients who are pregnant. We may see women who have pain related to normal orthopedic changes during pregnancy or women who become injured during pregnancy. We may even see pregnant patients who are looking to improve their health and fitness levels in order to prevent unwanted complications during pregnancy and the labor process (we will explore this further in this article). For these reasons, it is very important that we understand pregnancy and are able to prescribe safe exercise during pregnancy.
Where do we stand on exercise during pregnancy?
Historically, pregnant women were believed to be vulnerable and were advised to reduce their activity levels to ensure safety to oneself and one’s unborn baby. Recently, the American College of Obstetricians and Gynecologists (ACOG) has updated its recommendations for exercise to be less restrictive. Despite this recent update of recommendations for pregnant women, a survey of physicians (OB/GYN and primary care physicians) revealed that more than 60% were unfamiliar with current ACOG guidelines for exercising during pregnancy.
In theory, the addition of exercise during pregnancy may represent a significant challenge to both the mother and fetus due to the additional stresses it may impose on the physiological demands of pregnancy. Previous concerns of exercising during pregnancy were related to increased body temperature, decreased uterine blood flow, decreased nutrition to the fetus, and induced preterm labor.
However, recent studies have shown that exercising during pregnancy is a safe practice and may actually benefit the mother and fetus.
Pregnancy is life-changing for many women and may require lifestyle changes, such as smoking cessation, healthy eating, and routine exercise. Physical inactivity and excessive weight gain are now recognized as independent risk factors for maternal obesity and related pregnancy complications, including gestational diabetes and preeclampsia. It has also become evident that some of the less desirable aspects of pregnancy, such as physical discomfort, the effect of weight gain on self-image, and complications during labor and delivery may be alleviated with exercise.
Normal physiological changes during pregnancy
Contrary to the mainstream belief that pregnancy lasts only 9 months, full term pregnancy is 40 weeks (10 months). The first trimester lasts for the first 12 weeks of pregnancy, while the second trimester spans weeks 13-28, and the third trimester from weeks 29-40. During this period, there are many physiological changes that occur in order to accommodate the fetus and ensure a safe environment for growth and prosperity.
In order to accommodate the fetus, there is an increase in resting heart rate and stroke volume, along with a decrease in vascular resistance. Interestingly, left ventricular hypertrophy similar to that which is seen in trained endurance athletes may also occur in order to combat the increased cardiac workload during pregnancy.
- Increased joint laxity. This is due to the release of the hormone relaxin, which peaks during the first trimester and during delivery in order to loosen the ligaments of the pelvis to allow passage of the child through the vaginal canal. Sacroiliac joint laxity leads to augmented lumbar lordosis and an increased anterior pelvic tilt of 4° on average. This increase in lumbar lordosis is worsened by the anterior shift of the mother’s center of mass and may lead to complaints of low back pain.
- Gait changes. These include increased stance width of up to 30%, decreased stride length, and a longer stance phase. This wider base of support is thought to reduce lateral sway in order to provide stability during gait. Another common observation during pregnancy is a collapse of the medial longitudinal arch, which leads to increased pronation during stance and may contribute to longer foot length commonly seen during pregnancy. Increased pronation of the midfoot and rearfoot leads to increased tibial rotation, which can result in increased shearing forces at the knee joint and may serve as a major contributor to lower extremity pain.
Healthy weight during pregnancy
Many women feel that during pregnancy they can eat as much as they want due to the increased caloric needs of the fetus. However, they are only required to increase their caloric intake by 300 calories per day. Healthy weight gain during pregnancy is as follows:
- Women with a normal BMI (18.5-24.9 kg/m²) should aim to gain 25-35 lbs
- Women who are considered overweight (25-29.9 kg/m²) should aim to gain 15-25 lbs
- Women who are considered obese (30 kg/m² and up) should aim to gain 11-20 lbs
Contraindications to exercise during pregnancy
- Hemodynamically significant heart disease
- Restrictive lung disease
- Incompetent cervix or cerclage
- Multiple gestations at risk of premature labor
- Persistent second or third trimester bleeding
- Placenta previa after 26 weeks gestation
- Premature labor during the current pregnancy
- Ruptured membranes
- Preeclampsia or pregnancy-induced hypertension
- Severe anemia
- Unevaluated maternal cardiac arrhythmia
- Chronic bronchitis
- Poorly controlled type 1 diabetes mellitus
- Extreme morbid obesity
- Extreme underweight (BMI <12 kg/m² )
- History of extremely sedentary life
- Intrauterine growth restriction during current pregnancy
- Poorly controlled hypertension
- Orthopedic limitations
- Poorly controlled seizure disorder
- Poorly controlled hyperthyroidism
- Heavy smoker
Now just because these are “relative” contraindications does not mean that we should ignore them. The physical therapist should still contact the referring physician to discuss these conditions if the patient presents with any of those mentioned above.
Safe exercise during pregnancy
Safety Guidelines in Pregnant Women
- Avoid supine position >3 minutes after the first trimester
- If laying on side, only lay on the left to avoid compression of the inferior vena cava
- Avoid positions in which the buttocks are higher than the chest
- Avoid strong abdominal compression/strain during second and third trimester
- Avoid rapid bouncing, or swinging
- Avoid vigorous stretching of the adductors
- Do not use deep heat/electro modalities
- Avoid internal vaginal manual treatment
- Do not overheat and make sure to drink plenty of fluids
- Allow more time for warm-up and cool-down activities
- Exercise in a temperature-controlled room (be careful of outdoor activities unless weather is mild)
- No contact sports or activities with a high risk of falling
If table exercises are to be performed, recline the table 30° and utilize frequent breaks from this position in between sets while monitoring for discomfort.
In terms of exercise intensity, the current research recommends that pregnant women participate in moderate-intensity activities. I would suggest using the Borg Rate of Perceived Exertion Scale (RPE), which uses a scale between 6 and 20. The RPE score we are aiming for is 13-14, which corresponds to “somewhat hard”. Another simple method we can use to measure exertion is the “talk test”, which means that as long as a woman can carry on a conversation during exercise, then she is not overexerting herself.
Women who exercised on a regular basis prior to becoming pregnant may continue their current exercise regimen as long as it does not disobey any of the guidelines above. It is recommended that women who perform high-intensity exercise regularly before pregnancy gradually decrease the activity intensity as the pregnancy goes on in order to decrease the chance of injury. High-intensity exercise in excess of 45 minutes can lead to hypoglycemia and increases the chances of overheating.
- The intensity of exercise is too high
- There will be excessive abdominal compression/strain in an effort to stabilize the lumbar spine causing increased risk to the fetus
- Since the abdominal muscles are being excessively stretched due to the expansion of the uterus, they will not provide the stability necessary to prevent shearing forces in the lumbar spine, therefore increasing the chances of low back pain and injury
- Increased levels of the hormone relaxin place the mother in danger of ligamentous injury, which may lead to a negative cascade of musculoskeletal pain and dysfunction
- Heavy deadlifting may involve a brief period of Valsalva, which further increases intra-abdominal pressure
Effect of exercise during pregnancy on maternal and fetal outcomes
One of the biggest reasons pregnant women do not engage in physical activity is because of concerns about the safety of their unborn child. While the research is still building, several studies have proven that exercise can actually be beneficial to both a pregnant woman and her child.
Ying et. al – Effects of Exercise During Pregnancy to Prevent Gestational Diabetes: A Systematic Review and Meta-Analysis
Study: This study by Ying et. al included 6 RCTs, all exploring a primary outcome of incidence of gestational diabetes mellitus for a total of 2,164 patients. 3 of the studies utilized a cycling program, while the other 3 studies used exercise programs that follow the current ACOG guidelines for exercise (20-30 minutes of moderate intensity aerobic exercise on all or most days of the week).
Results: The study found that compared to the group that did not engage in exercise, the women in the exercise group showed a significantly lower incidence of gestational diabetes mellitus during pregnancy.
Perales et. al – Regular Exercise Throughout Pregnancy is Associated with a Shorter First Stage of Labor
Study: This study by Perales et. al is an RCT that included 166 pregnant women (83 control, 83 intervention). The authors set out to study the effects of exercise on the duration of the stages of labor. The experimental group exercised 3 days per week for 55-60 minutes. Each session began at 9-11 weeks gestation and terminated at the end of the third trimester. The exercise program included aerobic dance, lower extremity and core strengthening, balance, and pelvic floor muscle exercises with moderate intensity.
Results: Significant differences in duration of the first stage of labor were seen in the experimental group vs. the control (399.1 minutes experimental vs. 537.4 minutes control group). There were no significant differences found in duration of the second and third stages of labor.
Sanabria-Martinez et. al – Effects of Exercise-Based Interventions on Neonatal Outcomes: A Meta-Analysis of Randomized Controlled Trials
Study: This study by Sanabria-Martinez et. al included 105 sedentary, nulliparous pregnant women (52 experimental, 53 control) and compared the effects of an exercise program on postpartum testing of birth weight, length, head circumference, gestational age at delivery, and APGAR scores at 1 minute and 5 minutes against a control group (no exercise program). The exercise group participated in aerobic dance and strength training for 60 minutes, twice weekly with an additional 30 minutes of self-imposed physical activity on non-supervised days. The exercises on supervised days included abdominal stabilization work, pelvic floor muscle training, and “back exercises”.
Results: The authors of the study found significant differences in APGAR scores at 1 minute between the groups in favor of the exercise group. There were no statistically significant differences in mean birth weight, length, head circumference, and length of gestation. There were also no major health problems or adverse effects resulting from the exercise program.
Meher and Duley – Exercise or Other Physical Activity for Preventing Preeclampsia and its Complications
Study: This systematic review included 2 studies that evaluated the effects of an exercise program on women at risk for preeclampsia. The exercise included moderate-intensity aerobic exercise for at least 30 minutes per week (true duration and frequency were not mentioned).
Results: The experimenters found no significant differences between the exercise group and the control group, however, they concluded that the trials included were too small and that much more research is needed in this area of study.
As discussed above, moderate-intensity exercise during pregnancy has been shown to be safe to the mother and her unborn child. While more research is still necessary for this specific area of study, we know enough to understand that there are positive effects of exercise during pregnancy, such as relief from insomnia and anxiety, decreased incidence of musculoskeletal pain, and improved sense of body-image.
Although the research is still fairly new in this field, we already have enough evidence stating that exercise can decrease the incidence of gestational diabetes, shorten the first stage of labor, and improve APGAR scores at 1 minute postpartum. It is only a matter of time before we see the emergence of more high quality studies demonstrating additional benefits of exercise during pregnancy.
I came across some interesting findings during my research for this article. One similarity that stuck out in my mind is that the successful exercise programs included some combination of aerobic activity, abdominal strengthening, and pelvic floor muscle exercises. I believe this combination of exercises should be used with all physically active pregnant women. This will help alleviate some of the pain and discomfort felt during pregnancy and the stages of labor. These exercises can also help mitigate faster recovery after vaginal and cesarean delivery.
Despite the evidence presented above, the percentage of women who exercise during pregnancy remains very small. It is up to us as physical therapists to be sharp with our knowledge and be aware of the research in order to help grow this great profession and enhance the populations that we serve.
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Sanabria-Martínez, G., García-Hermoso, A., Poyatos-León, R., González-García, A., Sánchez-López, M., & Martínez-Vizcaíno, V. (2016). Effects of Exercise-Based Interventions on Neonatal Outcomes. American Journal of Health Promotion,30(4), 214-223. doi:10.1177/0890117116639569
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Ying Yu, Rongrong Xie & Cainuo Shen (2017): Effect of exercise during pregnancy to prevent gestational diabetes mellitus: a systematic review and meta-analysis, The Journal of Maternal-Fetal & Neonatal Medicine, DOI: 10.1080/14767058.2017.1319929