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Exercise During Pregnancy

Albright, Elizabeth DO, PGY-2

doi: 10.1249/JSR.0000000000000277
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Address for correspondence: Elizabeth Albright, DO, PGY-2, Eglin Family Medicine Residency Program, 307 Boatner Road, Suite 114, Eglin AFB, FL 32542; E-mail: ebethalbrite12@gmail.com. Column Editor: John R. Hatzenbuehler, MD; E-mail: jhatz@intermed.com.

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Physiologic Changes (1):

  • Musculoskeletal:
    • ○ Weight gain
    • ○ Shifted center of gravity: due to increased lumbar lordosis caused by anterior pelvic rotation
    • ○ Increased ligamentous laxity: from increased progesterone and relaxin
    • ○ Most sports-related injuries are secondary to joint laxity and lower extremity edema
  • Cardiac:
    • ○ Increased blood volume: up to 50% at term
    • ○ Increased heart rate: resting HR can increase 10 to 15 bpm
    • ○ Increased stroke volume and cardiac output
    • ○ Decreased systemic vascular resistance and blood pressure
  • Respiratory:
    • ○ Increased tidal volume and minute ventilation: up to 50%
    • ○ Physiologic decrease of pulmonary reserve
      • ▪ Increased work load with decreased oxygen availability
      • ▪ Physiologic respiratory alkalosis: not always enough to compensate for metabolic acidosis of strenuous exercise
  • Temperature regulation:
    • ○ Dependent on hydration status and environment
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Fetal Response (1):

  • Increased fetal heart rate (FHR) 10 to 30 bpm over baseline during/immediately after exercise
  • No clinically significant difference in birth weight
  • Cohort study assessed umbilical artery blood flow, FHR, and biophysical profile before/after exercise: 30 min of exercise was well tolerated by fetus.
  • Improved fetal tolerance of labor process
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Maternal Benefits (1,4):

  • Improvement/maintenance of fitness
  • Decreased overall pregnancy weight gain
  • Decreased incidence of gestational diabetes mellitus (GDM)
    • ○ Improved blood glucose control in patients with GDM
  • Reduced risk of preeclampsia
  • Decreased intrapartum interventions including pitocin augmentation and operative vaginal or cesarean deliveries
  • Decreased labor time
    • ○ Twice as likely to progress from 4 to 10 cm in <4 h
    • ○ Decreased length of the second stage of labor from an average of 60 to 36 min
  • Decreased postpartum recovery time
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Recommendations for Exercise Program (1,2):

  • The goal of exercise during pregnancy is to improve maternal fitness without increased risk to the mother or baby.
  • Motivational interviewing is key. Studies show that patients are more likely to start/continue an exercise program and healthy diet if recommended by a physician.
    • ○ Pregnancy is the ideal time to discuss; most patients are highly motivated to do what is best for the baby.
  • Patient categories:
    • ○ Previously sedentary: recommend gradual progression of exercise beginning with walking program
    • ○ Previously active: no safe upper level of intensity established. The consensus is to continue previous fitness routine if the patient regularly exercises before pregnancy and has an uncomplicated pregnancy.
  • General guidelines:
    • ○ Up to 40 min of moderate exercise is well tolerated by low-risk pregnant women (3)
      • ▪ Beyond 40 min, maternal glucose levels decrease and effects are unstudied
    • ○ Ensure adequate hydration
    • ○ Walking, strength training, and water exercises are safe for almost all women
      • ▪ Biking is safe during the first trimester but advised against as pregnancy progresses because of balance changes and fall risk.
    • ○ Avoid activities with:
      • ▪ High risk of fall/impact
      • ▪ High heat/humidity
      • ▪ Static and supine poses
        • • Patients may do yoga or Pilates but should modify certain poses.
        • • Supine poses are specifically not recommended during the second and third trimesters because these cause decreased venous return.
      • ▪ Exertion at altitudes >6000 ft
      • ▪ Scuba diving: fetal pulmonary circulation is not mature enough to filter bubble formation, high risk of decompression sickness in the fetus
    • ○ Stop exercise if any of the following occur:
      • ▪ Vaginal bleeding or leaking fluid
      • ▪ Regular contractions
      • ▪ Dyspnea before exercise
      • ▪ Dizziness
      • ▪ Headache
      • ▪ Chest pain
      • ▪ Muscle weakness affecting balance
      • ▪ Calf pain or swelling
  • Contraindications to exercise
    • ○ Hemodynamically significant heart disease
    • ○ Restrictive lung disease
    • ○ Incompetent cervix/cerclage
    • ○ Multiple gestation
    • ○ Second/third trimester bleeding
    • ○ Placenta previa after 26 wk of gestation
    • ○ Premature rupture of membranes or labor
    • ○ Preeclampsia
    • ○ Severe anemia
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References

Committee Opinion No. 650 Summary: physical activity and exercise during pregnancy and the postpartum period. Obstet. Gynecol. 2015; 126:e135–42.
    Herring SA, Bergfeld JA, Boyajian-O’Neill LA, et al. Female athlete issues for the team physician: a consensus statement. Med. Sci. Sports Exerc. 2003; 35:1785–93.
    Mottola MF, Inglis S, Brun CR, Hammond J. Physiological and metabolic responses of late pregnant women to 40 min of steady-state exercise followed by an oral glucose tolerance perturbation. J. Appl. Physiol. 2013; 115:597–604.
    Price BB, Amini SB, Kappeler K. Exercise in pregnancy: effect on fitness and obstetric outcomes—a randomized trial. Med. Sci. Sports Exerc. 2012; 44:2263–9.
    Copyright © 2016 by the American College of Sports Medicine.