Pregnancy and Exercise

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Pregnancy and Exercise

• Emily Jones, MD
• May 12, 2009

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Objectives

• Discuss anatomical and physiological changes that
  occur during pregnancy
• Discuss how these changes affect exercise in
  pregnancy
• Review Risks/benefits of
• exercise in pregnancy
• Review Exercise prescription
• and counseling for pregnancy

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Anatomical Changes uterus

• Expanding uterus
• Elevated center of gravity
• Progressive lumbar lordosis
• Theoretical increased risk of fall
• 40 to 50 report lower back pain

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Back pain

• Other recommendations
• Support belts
• Water exercise
• Core exercises
• Tylenol

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Anatomical Changes weight

• Increased total body weight
• 25lbs average weight gain
• Causes 5 x the weight on joints
• Soft tissue edema occurs in gt80
• Can cause nerve entrapments or compression
  neuropathies
• Carpal tunnel most common

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Anatomical changes ligamentous laxity

• Increases as pregnancy progresses
• ? Due to increase in relaxin
• Widening of symphysis pubis
• SI joint laxity
• Increase pain SI, pubic
• Peripheral joint laxity
• No known evidence of laxity leading to increased
  injuries

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Pregnancy Physiology Cardiovascular

• Blood Volume increases up to 50
• Sodium/total water retention
• Heart Rate increases 20
• Stroke volume increases
• CO up by 30 to 50 (1.5L)
• SVR decreases (progesterone) contributes to MAP
  one by 5 to 10mm
• Especially 2nd trimester

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Pregnancy Physiology Cardiovascular
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Pregnancy physiology with exercise

• Heart rate normal response vs blunted
• Max HR no longer guide to monitoring intensity
  during pregnancy
• Previous ACOG guidelines were to not exceed
  140bpm
• Currently recommended to use
• perceived exertion
• Borg scale
• Talk test

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Pregnancy physiology with exercise

• No shown adverse effects on uterine blood flow
  due to redistribution to exercising muscles
• FHR usually up 10 to 30 beats in response to
  maternal exercise
• FHR decreases seen in 9

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Pregnancy Physiology Respiratory Physiology

• Increased secretions
• Increased chest circumference ( 2cm)
• Diaphragm rises up to 4cm
• Decreased FRC 20, respiratory reserve volume
• Increased oxygen consumption 20
• Increased Tidal Volume 30 to 50
• Increased minute ventilation
• Primary respiratory alkalosis of pregnancy
• No Change FEV1

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Respiratory Physiology
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Respiratory with exercise

• Subjective and max exercise performance decreased
• During mild exercise increased respiratory
  frequency, min ventilation and oxygen
  consumption
• During moderate to intense exercise seems to
  overwhelm adaptive changes that occur at rest
• Respiratory frequency decreases, lower TV and max
  O2 consumption

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Respiratory with exercise
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Pregnancy physiology Thermoregulatory

• Increased basal metabolic rate
• Increased heat production
• Better heat dissipation in pregnancy
• Increased surface area and SVR
• Increased risk of dehydration

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Pregnancy Physiology Thermoregulation with
exercise

• In non-pregnant controls body temp increases 1.5
  deg C during moderate intensity exercise in the
  first 30 min
• 60 minutes at 55 VO2 max in pregnant women
  increase of 0.6 deg C
• In animal studies maternal temp increase of
  gt1.5 deg C associated with major congenital
  malformations
• Suggestive that maternal hyperthermia gt39 deg C
  during first 45 to 60 days may be teratogenic
• No conclusive studies in humans
• Hyperthermia associated with exercise never
  directly associate with teratogenic

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Pregnancy outcomes improved by exercise

• Gestation Diabetes
• Preeclampsia
• Weight gain
• Improved mental health
• Overall decreased
• subjective discomforts

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Delivery outcomes improved

• Decreased time of active labor
• Decreased interventions
• pitocin, forceps, c-section
• Increased fetal tolerance of delivery

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Labor after Endurance Exercise in Pregnancy
Exercise (n87) Control (n44)
Incidence of PTL 9 9
Length of Gestation 277 d 282 d
Incidence of c-section 6 30
Incidence of operative vaginal delivery 6 20
Duration of labor 264 min 382 min
Clinical evidence of fetal distress 26 50
Am J Obstet Gynecol 163 1799-1805, 1990.
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Gestation Diabetes

• Retrospective studies show exercise can decrease
• Especially in BMI gt 33
• Minimal data on diabetics
• Greater normalization of glycemic control after 4
  weeks than diet alone
• Decreased insulin need

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Gestational Diabetes
Author, year Study type Activity period size RR, OR, CI
Dempsey et al (2004) Case-control Year before 1st 20 weeks Both periods 155 cases 366 controls Any vs. none 0.45 (0.28-0.74) Vigorous vs. none 0.29 (0.16-.51) vs. none 0.52 (0.33-0.80) Vigorous vs. none 0.34 (0.19-0.63) Active both vs. inactive both 0.40 (0.23-0.68)
Dempsey et al (2004) Prospective Year before 12 weeks Both 909 Any vs. none 0.44 (0.21-0.91) Any vs. none 0.69 (0.37-1.29) Any vs. inactive both 0.31 (0.12-0.79)
Zhang et al prospective Potentially 10yrs before pregnancy 21,765 Mean weekly total activity score highest vs. lowest quintile 0.81 (0.68-1.01) Mean weekly vigorous activity score highest vs. lowest quintile 0.77 (0.69-0.94) Brisk/very brisk walking vs. casual walking with no vigorous activity 0.66 (0.46-0.95) 15 flights stairs/day vs 2 flights stairs/day with no vigorous activity 0.50 (0.27-0.90)
Oken et al 2004 prospective Year before 20 weeks gest Both 1805 Vigorous vs. none 0.56 (0.33-0.95) Vigorous vs. none 0.90 (0.47-1.70) Any vs none 0.49 (0.24-1.01)
Dye et al 1997 Case-control Entire pregnancy 372 cases 12, 404 controls None vs. any 1.0 (0.8-1.3) BMI gt33.0 none vs. any 1.9 (1.2-3.1)
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Preeclampsia

• 43 decrease with moderate exercise vs. sedentary
• Shown in one study
• Risk decreases more with increasing time spent
  exercising

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Preeclampsia
Sorenson et al 2003 Case-control Year before 1st 20 wks preg Both 201 cases 383 controls Any vs. none 0.67 (0.42-1.08) Vigorous vs. none 0.40 (0.23-0.69) Any vs. none 0.65 (0.43-0.99) Vigorous vs. none 0.46 (0.27-0.79) Active both vs. inactive both 0.59 (0.35-0.98)
Saftlas et al 2004 Nested Case-control Year before lt16 wks preg 44 cases 2422 controls Virtually none assessed Any LTPA vs. no LTPA 0.66 (0.35-1.22) Nonsedentary jobs vs. sedentary jobs 0.71 (0.37-1.36)
Rudra et al 2005 Case-control Year before preg 244 cases 470 controls Perceived very strenuous to maximal exertion vs. perceived exertion of none to weak 0.22 (0.11-0.44) BMI lt25 trend of lower risk with increasing perception of exertion (Plt0.001) BMI 25 trend of lower risk with increasing perception of exertion (Plt0.001)
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Debunking the risks of aerobic exercise

• No increased risk of
• Misscarriage
• Congenital malformations
• Ectopic
• Pre-term labor
• Placental insufficiency
• IUGR
• Unexplained fetal deaths

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Exercise and Birth Weight

• One study showed continuation of exercise at or
  above 50 preconception levels significant
  reductions (-310g)
• Another trial showed no difference b/w birth
  weight with non-exercises and vigorous exercises
• One study found longer duration exercise (40 to
  60min 4-5 x week) of moderate, weight-bearing
  reduced growth, but reducing duration to 20 min
  increased growth
• Meta-analysis of 30 studies no difference except
  in vigorous exercises in 3rd trimester decreased
  fetal weight 200 to 400g

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Pre-term birth

• No increased risk in exercising women with
  uncomplicated pregnancy and no other risk factors
  for pre-term labor
• Physical activity associated with a slight
  increase in uterine contractions
• Dehydration can worsen

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Contraindications

• Absolute
• Significant cardiac disease
• Restrictive lung disease
• Cervical incompetence
• Multiple gestation
• Placental abruption
• Placenta previa
• Premature labor
• Rupture of membranes
• preeclampsia

• Relative
• Severe anemia
• Unevaluated arrhythmia
• Bronchitis
• Poorly controlled DM, htn, sz d/o, thyroid dz
• Extreme obesity or low BMI
• Sedentary lifestyle
• Fetal growth restriction
• Heavy smoking

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ACOG 2002 Guidelines

• In the absence of contraindications, pregnant
• women should be encouraged to engage in
  regular, moderate intensity physical activity to
  continue to derive health benefits during their
  pregnancies as they did prior to pregnancy
• 30 minutes or more of moderate exercise per day
  recommended
• Avoid the supine position during exercise as much
  as possible
• Recommend against scuba diving during pregnancy,
  sports at risk for abdominal trauma

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ACOG 2002 Guidelines cont.

• Exercise may benefit women with gestational
  diabetes
• Competitive athletes may require close obstetric
  supervision
• Moderate exercise during postpartum does not
  negatively impact nursing and neonatal weight
  gain
• Return to physical activity after pregnancy
• reduces the risk of postpartum depression

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Exercise prescription

• Very similar to non-pregnant individuals
• Sedentary women can safely begin exercising
  during pregnancy
• Need to be flexible adapt as pregnancy
  progresses
• Active women may be advised to
• restrain from very strenuous
• activities and competition
• Pre-exercise medical screening

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Exercise prescription

• Type
• Intensity
• Duration
• Frequency
• Progression

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Plug for water exercise

• Centripetal shift in blood volume
• Lower forces across weight bearing joints
• Body heat readily dissipated
• Balance and falling
• not an issue

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What about weight lifting risks?

• Lower weights, multiple repetitions
• Avoid heavy or isometric
• No increased risk of injury
• No obvious positive/negative effects on weight
  gain pregnancy, complications, birth weight,
  pre-term labor
• Possibly helpful
• Core strength less lower back pain
• Better tolerate weight gain

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Exercise position

• Avoid supine position after 1st trimester
• Relative obstruction of venous return
• CO down 9
• Standing position
• CO down 18
• lower birth weights in women who worked standing
  during 3rd trimester

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Exercises to Avoid

• Contact sports
• Hockey, basketball, soccer
• Risk of trauma
• Skiing, biking, gymanstics, horseback riding
• Scuba diving
• Decompression problems fetus
• Altitude
• Decreased oxygen

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Intensity

• Moderate intensity 3 to 4 METs as with
  non-pregnant
• To develop or maintain physical fitness up to 6
  to 7 METs also appears safe if pregnancy
• Tailor on pre-pregnancy fitness
• Use RPE, talk test
• No longer use HR cut off

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Duration

• At least 150 min/week of moderate intensity
• Careful attention to hydration, heat and caloric
  intake in exercise gt 45 min in pregnancy

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Nutritional Recommendations

• Approximately 300kcal/day more
• Slightly more 2nd tri, slightly less 3rd
• More if exercising
• Increased risk of hypoglycemia
• Increased carbohydrate need

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Glucose utilization
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Frequency and Progression

• Similar recommendations to non-pregnant
• Expect activity and fitness level to decrease as
  pregnancy progresses

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Warning signs to Terminate Exercise

• Vaginal bleeding
• Dyspnea prior to exertion
• Dizziness
• Headache
• Chest pain

• Muscle weakness
• Signs of thrombophlebitis
• Uterine contractions
• Decreased fetal movement
• Leakage of fluid

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NCAA guidelines

• Guideline published 2002
• Acknowledges lack of research addressing intense
  physical exercise pregnancy
• Cite expert opinion recommending to avoid
  participation in contact sports after 14 wks EGA
• Team physician job is to advise student-athlete
• - Risk, benefits, effects on competitive ability
• - One-year extension of 5 yr eligibility period
  for reasons of pregnancy
• Signed informed consent recommended if athlete
  chooses to compete

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Postpartum

• Probably safe to resume training within 2 weeks
  of delivery in competitive
• No proof of increased injury to pelvic
  floor/abdominal muscles
• Faster regain of abdominal muscles
• Improved bladder control
• Care with return to high impact
• activities such as running
• Decreased post partum depression
• Increased weight loss

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Postpartum breastfeeding

• Overall no decrease in ability to breastfeed when
  exercising
• Strenuous training can decrease milk production
  in breast feeding women
• Feed prior to exercise
• Decreased discomfort from engorged
• Less chance of acidity in breast milk

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Summary

• Many anatomical and physiological changes during
  pregnancy
• Pregnant women should be encouraged to exercise
  regularly
• Flexible and individual exercise prescription
• Avoid contraindicated exercises and conditions
• Heat, altitude, depth
• Continue exercising postpartum