exercise during pregnancy

Safe Exercise During Pregnancy: What Physical Therapists Need to Know

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.

The purpose of this article is to inform physical therapists of the benefits of exercise during pregnancy and to provide safety guidelines and background information necessary in order to prescribe a safe and effective exercise program.

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.

It is important to note that a thorough clinical evaluation should be conducted by the patient’s obstetrician/gynecologist before an exercise program is recommended to ensure that the patient does not have a medical reason to avoid exercise. Women who have been labeled with the condition “high risk pregnancy” may be prescribed bed rest and may not be allowed to begin exercise. Although bed rest is only rarely indicated for these patients, physical therapists should follow the regulations set forth by the physician in this case.

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 this section, I will briefly describe some of the cardiovascular and orthopedic changes seen during pregnancy. It is important for practitioners to understand the normal physiological changes so that we may recognize abnormal signs and refer back to the OB/GYN as necessary.

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.

In addition to these changes in the cardiovascular system, there are also changes in the musculoskeletal system that result from pregnancy, which leads to biomechanical changes during daily function. Some of these include:

  • 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.
A 20% increase in body weight can double the force placed on a joint, which may increase the chance of lower extremity muscle strains, cramps, fatigue, and soreness, especially during the second and third trimesters.

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
Excessive weight gain during pregnancy is strongly associated with many serious maternal and fetal complications, such as gestational diabetes mellitus and preeclampsia.

Contraindications to exercise during pregnancy

Absolute contraindications

  • 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

Relative contraindications

  • 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.

If any patient experiences vaginal bleeding, regular painful contractions, amniotic fluid leakage, dyspnea before exertion, dizziness, headache, chest pain, muscle weakness affecting balance, or calf pain or swelling, exercise should be terminated and the patient should be referred for a re-evaluation.

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.

If the question ever arises, the preferred sleeping position for pregnant women is the semi-fowler position while side-lying on the left.

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.

I recently saw a video on social media posted by a strength coach who was having his client, who was 6-months pregnant, perform heavy barbell deadlifts. This sort of activity can be very dangerous to the maternal and fetal health for the following reasons:

  1. The intensity of exercise is too high
  2. There will be excessive abdominal compression/strain in an effort to stabilize the lumbar spine causing increased risk to the fetus
  3. 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
  4. 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
  5. 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.

In this section, I will use several studies to briefly discuss the effects of exercise on outcomes such as birth weight, gestational diabetes, preeclampsia, and the stages of labor.

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.

Interested in safe exercise after pregnancy too? Check out this article for an orthopedic perspective on postpartum physical therapy.

Final thoughts

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.

Due to the emerging evidence on the topic, I also believe that our profession is very close to the point of receiving regular referrals from obstetricians/gynecologists for routine strengthening and conditioning programs with pregnant women in order to decrease the incidence of complications during and after pregnancy.

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.

References

Anselmo, D. S., Love, E., Tango, D. N., & Robinson, L. (2017). Musculoskeletal Effects of Pregnancy on the Lower Extremity. Journal of the American Podiatric Medical Association, 107(1), 60-64. doi:10.7547/15-061

Barakat, R., Perales, M., Bacchi, M., Coteron, J., & Refoyo, I. (2014). A Program of Exercise Throughout Pregnancy. Is It Safe to Mother and Newborn? American Journal of Health Promotion, 29(1), 2-8. doi:10.4278/ajhp.130131-quan-56

Committee Opinion No. 650. (2015). Obstetrics & Gynecology, 126(6). doi:10.1097/aog.0000000000001214

Haakstad, L. A., & Bø, K. (2011). Exercise in pregnant women and birth weight: a randomized controlled trial. BMC Pregnancy and Childbirth, 11(1). doi:10.1186/1471-2393-11-66

Hinman, S. K., MD, PhD, Smith, K. B., MD, Quillen, D. M., MD, & Smith, S., MD, PharmD. (2015). Exercise in pregnancy: A clinical review. Sports health, 7(6). doi:10.1177/1941738115599358

Kelly, A. K., Harmon, K. G., & Rubin, A. (2005). Practical Exercise Advice During Pregnancy. The Physician and Sportsmedicine, 33(6), 24-30. doi:10.3810/psm.2005.06.104

Meher, S., & Duley, L. (2006). Exercise or other physical activity for preventing pre-eclampsia and its complications. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.cd005942

Perales, M., Calabria, I., Lopez, C., Franco, E., Coteron, J., & Barakat, R. (2016). Regular Exercise Throughout Pregnancy Is Associated With a Shorter First Stage of Labor. American Journal of Health Promotion, 30(3), 149-154. doi:10.4278/ajhp.140221-quan-79

Perales, M., Santos-Lozano, A., Sanchis-Gomar, F., Luaces, M., Pareja-Galeano, H., Garatachea, N., . . . Lucia, A. (2016). Maternal Cardiac Adaptations to a Physical Exercise Program during Pregnancy. Medicine & Science in Sports & Exercise,48(5), 896-906. doi:10.1249/mss.0000000000000837

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

Tinius, R. A., Cahill, A. G., & Cade, W. T. (2016). Origins in the Womb: Potential Role of the Physical Therapist in Modulating the Deleterious Effects of Obesity on Maternal and Offspring Health Through Movement Promotion and Prescription During Pregnancy. Physical Therapy. doi:10.2522/ptj.20150678

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

About Nicholas Mazzone

Nicholas Mazzone
Nick is a physical therapist and certified strength and conditioning specialist from Staten Island, NY. He earned his doctorate in physical therapy from Stony Brook University in 2016. Nick currently works in an outpatient orthopedic sports clinic and is an independent contractor working with pre-school and school-aged children in Staten Island, NY.

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