1. Exercise in Pregnancy

2. Objectives
Discuss risks and benefits of exercise for both mother and baby
Describe physiologic adaptations to exercise during pregnancy
Review absolute and relative contraindications to exercise during pregnancy
Prescribe an individualized exercise program for a pregnant athlete
Practice what we preach !
Must add that much of what we will discuss today is UNPROVEN, in the sense that there are really no randomized, double-blind placebo-controlled studies to support some of the data presented. However, there are also no high quality studies demonstrating a reduction in morbidity and mortality in individuals who use a parachute when jumping from an airplane, and yet this is (for obvious reasons) still a recommended practice! So we must think through the overall benefits of exercise in pregnancy without the assistance of large volumes of data.

3. “We are all athletes…some of us are in training, and some of us are not”

4. Historical Perspective
“The midwives answered Pharaoh, ‘Hebrew women are not like Egyptian women; they are vigorous and give birth before the midwives arrive.’”
Exodus 1:19

5. Fun Facts ↑ longevity ↑ HDL, ↓ triglycerides ↓ cancer risk
↓ proinflammatory cytokines
↓ oxidative stress
Improved psychological well-being
↑ HDL, ↓ triglycerides
↓ blood pressure
Improved endothelial function
Improved glycemic control
↓ risk of CAD
Obviously there are many more than just those listed!
Many of these exercise-induced health benefits can serve to counteract hormonal changes in pregnancy (incr TG’s, incr LDL, decr HDL)
BP reduction may be important for PIH/Pre-eclampsia, especially when considering the increased pro-inflamm cytokines, oxidative stress assoc w/ these conditions.
Improved glycemic control may decrease risk of gestational diabetes mellitus (GDM).

6. Improved sense of well-being
Continued…
↑ energy
↓ weight gain
↑ strength/endurance
↓ back pain
Improved sleep
Improved sense of well-being
↓ risk GDM
↓ risk pre-eclampsia
What women complain of most…gaining wt, no energy, inability to sleep, worsening back pain, fears about rigors of labor, pp depression, etc…may all be mitigated by exercise during pregnancy
As we’ll see, may also affect mode of delivery, child development, etc…

7. CDC and ACSM Recommendations:
Continued…
CDC and ACSM Recommendations:
30-60min moderate-intensity physical activity “on most—preferably all—days of the week”
At least 60min to prevent weight gain, increase fitness, achieve full health benefits
Now, how many of us are living up to those goals…? This is daunting for busy physicians…as well as for our patients.

8. (Not So) Fun Facts Less than 25% pregnant women exercise regularly
40-60% are completely inactive during pregnancy
Pregnancy seen as “confinement”
Non-white women 50% less likely to exercise
Rest/relaxation seen as more important
Most women decrease or stop all exercise while pregnant
Pregnancy seen as confinement until recently w/ new research.
More likely to exercise if white, educated and older (very few of our patients!)
Rest and relaxation more important—source of info = family, friends, the media…we are not doing a good job educating our patients on the benefits of exercise.

9. ACOG Guidelines (1985) Overly conservative HR <140bpm
No exercise over moderate intensity
No longer than 15min
Avoid valsalva (weight lifting)
No exercise in supine position after 1st trimester
Overly conservative and based on very limited information.
How difficult it would be to keep exercise at moderate intensity or less, and HR less than 140, NO longer than 15 min…
Not many female athletes during that time…which has since changed.

10. Where We’ve Come From Zahereiva et al.
-27% female athletes competing consecutively gave birth between Olympic games
-most report feeling ‘more fit’ after childbirth
“They became stronger, had greater stamina and were more balanced in every way after having a child.”
Zahereiva et al.—retrospectively looked at women competing in consecutive Olympic games. Most resumed vigorous training 3-6mo post-partum, and continued to train at mod intensity during pregnancy.
Most women also achieved GREATER performances post-delivery than they had beforehand.

11. Physiologic Adaptations during Pregnancy and Exercise
Cardiovascular
Pulmonary
Thermoregulatory Control
Musculoskeletal

12. Cardiovascular Rest Exercise ↑ plasma volume ↓ BP
↑ baseline heart rate
↑ cardiac output
↑ stroke volume
↓ systemic vascular resistance
Exercise
↓ BP
↓ vagal tone as pregnancy advances
Blunted HR response to exercise
Decrease in BP during exercise is POSSIBLE, and is a consequense of a greater decrease in SVR than an increase in CO.
Decrease vagal tone causes an increased HR (not in all cases).
Blunted response to catecholamines during exercise can decrease the nl increase in HR that normally occurs w/ exercise, more during the 3rd trimester.
This is why you can’t really use HR as a guide to intensity of exercise as you are otherwise able to do in other populations.

13. ACOG Recommendations:
Continued…
ACOG Recommendations:
Avoid exercise in supine position after 1st trimester
Avoid prolonged standing
HR > 140 now allowed
Exercise in supine position after 1st trimester causes obstruction of venous return from enlarging uterus compressing inferior vena cava.
Prolonged standing (OR nurses, etc.) also causes venous pooling and decreased venous return, decreased CO, etc. and can be dangerous to mother and baby.
TALK TO YOUR OB! Many think that since trained athletes should have low resting HR’s anyway, that they shouldn’t be going over the 140 limit unless something is wrong (volume depletion, etc.)

14. Pulmonary Rest ↑ tidal volume ↑ oxygen uptake
↑ resting oxygen requirements
↑ work of breathing
Exercise
↓ oxygen available for exercise
↓ maximum performance
SOB with less exertion
Minute ventilation increased by 50% secondary to increase in tidal volume and oxygen uptake.
Increased work of breathing secondary to pressure of uterus under diaphragm.
Progesterone-mediated increased sensitivity to CO2, so respiratory rate also goes up at baseline.

15. ACOG Recommendations:
Continued…
ACOG Recommendations:
No specific recommendation, except…
Exercise intensity should be based on symptoms

16. Thermoregulatory Control
Rest
↑ basal metabolic rate
↑ heat production
Fetal core body temp 1ºC higher
↑ blood supply to skin
Lower sweating threshold
Exercise
↑ temp related to exercise intensity
↑ conduction of heat to periphery
Moderate exercise ↑ core temp 1.5° first 30min
↑ teratogenic risk?
Increased BMR, increased heat production, all compensated for by increased RR, CO, blood flow to skin, and decreased sweating threshold.
Teratogenic risk is THEORETICAL based on animal models, experiments conducted using rats and putting them in stressful situations, (food deprivation, etc.) and allowing body temp to rise, causing neural tube defects in rat offspring…extrapolated to humans.
Also encouraged pregnant women to avoid hot-tubs, as increased risk of NTD may result as well.
Relatively well-designed studies have been performed, there is NO ASSOCIATED RISK OF NTDs OR OTHER TERATOGENIC EFFECTS in babies of women who exercise during pregnancy.
Moderate increase in body temp after 1st 30 min plateaus, then may even decrease slightly. But this was using moderate-intensity exercise in THERMONEUTRAL conditions.

17. Clap et al. Continued… Results:
- 10 recreational joggers
- core body temp measured during moderate intensity exercise
- pre-pregnancy, 20 and 32wks
Results:
- increase in core body temp, but less so in pregnancy (1°C lower)
- due to decrease in sweating threshold, etc.
- thus NTD not likely in humans
Again, small numbers so cannot draw large-scale conclusions.

18. ACOG Recommendations:
Continued…
ACOG Recommendations:
Avoid hot, humid conditions, high altitudes
Wear appropriate clothing
Stay hydrated!
Innate physiologic protection against hyperthermia
If you’re going to go out, go early morning or late evening, take water, decrease intensity if hot, humid, or exercise indoors.
Example of marathon runner in south tx, completed feat during 1st trimester (pt was unaware).

19. Musculoskeletal Rest Exercise Center of gravity up and forward
↑ back pain
↑ joint laxity
Weight gain
Exercise
May negatively affect balance
↑ force across hips/knees up to 100% in wt bearing
↑ fall risk?
↑ instability, risk for injury?
Fall risk, instability and joint laxity as a predisposing factor to injury are all unproven, just hypothesized based on physiologic changes.

20. ACOG Recommendations:
Continued…
ACOG Recommendations:
No specific guidelines
Adjust activity based on gestational age, symptoms
Stretching/strengthening exercises

21. Exercise and Gestational Diabetes
Improves glucose tolerance, blunts insulin response
# hrs spent in exercise – ↓ risk of GDM
- Case control: 155 pts w/ GDM vs. 386 controls
First 20 wks — 48% reduction GDM
Greatest when combined w/ exercise 1yr prior
- ≥ 4.2 hrs/wk mod intensity exercise – ↓ 76%
May prevent initiation of insulin
GDM is a d/o of carbohydrate metabolism…diagnosed by glucose tolerance test in office or hospital setting.
Exercise increases cells’ responsiveness to insulin, and can ‘push’ glucose into cells more efficiently. In addition, you are also using up glucose quicker during exercise.
Dempsey study—case control. Designed by handing out survey’s about type, intensity, duration and frequency of exercise during year before pregnancy and during first 20wks gestation. Results: the number of hours spent performing recreational activities and the energy expended were related to decreased in GDM risk. In addition, DAILY STAIR CLIMBING when compared w/ none, was assoc w/ 49-78% reduction in risk.
2nd study—1000 women, w/ greatest risk reduction seen in women exercising for greater than 4hrs during week at mod intensity level.
Results: approx 30min/day of mod intensity exercise may decrease risk of GDM.
This was AFTER confounding variables were accounted for.
In addition, exercise may have SAME effect as pharmacologic therapy!
Unfortunately this is another case-control study, cannot draw hard and fast conclusions, but rather use this information to encourage further study in this important area.

22. Exercise and Pre-eclampsia
Reduces risk (40%)
- inversely related to time/intensity
Sorensen et al.
201 pre-eclamptic vs. 383 controls
- “any regular physical activity” first 20 wks %
- light/mod vs. vigorous % vs. 54%
- brisk walking (≥ 3mi/hr) %
- vigorous exercise year prior %
- stair climbing (1-4 flights/d) %
Hypertensive d/o during pregnancy are second leading cause (after pulmonary embolism) of maternal mortality in US. Pre-eclampsia occurs in 3-7% of pregnancies.
Pathological features: impaired glucose tolerance, hypertryglyceridemia, chronic systemic inflammation, diffuse endothelial dysfunction. This is REMARKABLY SIMILAR to what is seen w/ essential HTN and Type 2 DM…exercise impacts ALL of these parameters in various ways.
Only 3 published studies on exercise and risk of preeclampsia.
MARCOUX—case control study, retrospective data collection w/ preeclampsia, 254 w/ GDM, 505 control. ALL PRIMIPS w/ no PMHx. Interviewed using questionnaire on type, freq, intensity, duration of exercise during first 20wks.
Results: those who regularly exercised had decreased incidence of preeclampsia (by 43%), same trend for gestational HTN.
SORENSEN—case control study, using questionnaire w/ same questions, during first 20wks of pregnancy and year before pregnancy.
Light activities—gardening and golf. Mod activities—cycling and casual swimming. Vigorous activities—running, aerobics, lap swimming.
Results: reductions as above, AFTER controlling for maternal age, race/ethnicity, parity, smoking status during pregnancy, and pre-pregnancy BMI. Multips and primips demonstrated similar reductions in incidence of preeclampsia. Exercise during both periods increased reduction to 41%. BUT small sample size and obvious selection bias, as well as difficulty of remembering physical activity (recall bias).
Women who are obese, like leaner counterparts, experience similar reduction in risk w/ increased energy expended on exercise.
THIS IS BIOLOGICALLY PLAUSIBLE. Exercise decreases BP, TGs, increases HDL, improves insulin sensitivity, reduces fat mass, decreases pro-inflamm cytokines. BUT exercise increases risk of oxidative stress---however it also increases antioxidant enzyme activity, which compensates for any possible increase in ox stress. Exercise also improves emotional well-being and reduces stress and anxiety…(investigations have shown increase in preeclampsia (3-fold) w/ depression/anxiety/stress.)

23. Other Benefits No ↑ risk of miscarriage Possible ↓ risk preterm birth
↓ risk of cesarean section ?
Faster recovery post-partum
Labor duration ?
Miscarriage thought to be increased secondary to hyperthermia, we have seen this is NOT really a factor in humans.
Reduction in pre-term birth? In one particular study, high-intensity exercising women were found to deliver 8d earlier than non-exercising or lightly exercising women.
Risk of c/s being reduced…this was after confounding variables were adjusted/corrected for…the decreased risk was 2x.
Labor duration—jury still out, some research suggests shortened 2nd stage but prolonged 1st stage, other studies show shortened overall duration.

24. Effects on Infant Placenta larger, greater surface area
Does not change uterine/umbilical blood flow
FHR – accelerations, mild decelerations, then baseline
Lower birth weight if vigorous exercise 5-6x/wk
Children lighter/leaner
Score higher on intelligence & oral language tests
Placenta—randomized controlled trial. In Ontario, Canada—examined term placenta of women who exercised during first half or all of pregnancy, and those who did not…result was increased parenchymal component of placenta, total vascular volume (more capillaries) and surface area…so better able to conduct blood flow to baby during exercise!
Uterine/umbilical blood flow—study in Germany and Turkey…Doppler U/S of 33 women w/ uncomplicated pregnancy and 10 women w/ IUGR (documented) after exercise on cycle ergometer—no significant alteration in uterine and umbilical perfusion in either group of patients.
CAVEAT— ALTHOUGH LIMITS HAVE BEEN EXTRAPOLATED FROM ANIMAL STUDIES, Mottola et al. suggested that intensity of 80% may be threshold above which fetal BF is significantly reduced. (But there is NO data supporting this!)
FHR—studies are very small, but there appears to be no increased risk for fetal bradycardia during maternal exercise or after.
Birth weight—meta analysis performed in 2003…over 30 studies included…conclusion that exercise during pregnanct does not appreciably affect BW except when mothers continue to ex vigorously into the third trimester. Average decrease in wt is grams.
Intelligence—case control prospective study of 20 women exercising vigorously vs. 20 women not ex at all. ALL WHITE, EDUCATED, HIGHER INCOME. Children of women who continues exercise were significantly lighter and leaner than controls but maintained axial, cranial growth and lean body mass as appropriate for gestational age. Also scored higher on tests of general intelligence and oral language skills—this was statistically significant. Groups were well-matched for education level, SES, etc. No current explanation for this observation…need more tests, obviously small group of women, so at this time just an interesting hypothesis that requires further research.

25. Current ACOG Guidelines
Even more liberal than previous
In absence of contraindications, pregnant women can follow ACSM recommendations
Avoid supine positions after 1st trimester
No reports that hyperthermia during exercise is teratogenic
Promotes exercise even in previously sedentary women…Next we’ll talk about ex prescription…and how to provide instructions for pt’s willing and ready to begin or continue an exercise program.

26. Exercise Prescription
Where to Start:
- Gather information for History & Physical Exam
- Gestational age
- Goals
- Grade
- “F I T T”
Get H&P—overall health, OB complications currently or in the past, medical problems that would preclude, etc.
Gestation—how far along are they, or is this preconception counseling? Because how far along your pt is determines what they are able to do.
Goals—if they were not a recreational athlete before, pregnancy is not the time to become one. What are their goals? To lose weight (need appropriate counseling as this is not the time to diet), get in shape for labor and to take care of baby, etc.
Grade—in other words, what kind of athlete are they…sedentary, elite, recreational, etc.
FITT—components of the exercise prescription that we will go over in the next slide.

27. “F I T T” Frequency- Intensity- Type- Time- “most days of the week”
THR vs. Borg scale
Type-
walking/biking/running/swimming
Time-
30-90min/day
Type—whatever they will do! But really for pregnancy, some things are not recommended, i.e scuba diving, downhill skiing, etc.
Time– there is a range. As we’ll see on the next slide, it depends on your pre-pregnancy fitness level.

28. Borg Scale

29. “F I T T” Frequency- Intensity- Type- Time- “most days of the week”
THR vs. Borg scale
Type-
walking/biking/running/swimming
Time-
30-90min/day
Type—whatever they will do! But really for pregnancy, some things are not recommended, i.e scuba diving, downhill skiing, etc.
Time– there is a range. As we’ll see on the next slide, it depends on your pre-pregnancy fitness level.

30. Sample Sedentary Recreational Elite Frequency Intensity Type Time
≥ 3x/wk
3-5x/wk
4-6x/wk
Intensity
65-75% MHR
RPE- mod hard
65-85% MHR
RPE- mod hard to hard
75-85% MHR
RPE- hard
Type
Walk, bike, stair, swim, aerobics
Also run/jog dance, tennis
Competitive activities
Time
30min
30-60min
60-90min

31. Stretching - static, not ballistic - hold for at least 1min
Continued…
Stretching
- static, not ballistic
- hold for at least 1min
Weight Lifting
repetitions
- low weight
Wt lifting—high wt (resistance exercise) may induce fetal bradycardia and cause HTN response in mother which may decrease uterine blood flow, etc.

32. Nutrition Four F’s: Food ↑ 150cal/day 1st - 2nd trimester
↑ 300cal/day 3rd trimester
Fluids ↑ 30ml/day
1 lb = 500cc
Fe (Iron)
Folate

33. Contraindications Absolute Relative PIH/Preeclampsia
Ruptured membranes
Incompetent cervix
2nd or 3rd trimester bleeding
Multiple gestation
Placenta previa after 26wks
Heart disease
Restrictive Lung disease
Premature labor
Relative
IUGR
Cardiac dysrhythmias
Severe anemia
Chronic bronchitis, heavy smoker
Poorly controlled DM, HTN, seizure d/o, thyroid dz
Extremes of weight
Orthopedic limitations
PIH/preeclampsia—this IS currently on the list for absolute contraindications, however recent research is showing that exercise may be an adjunctive treatment for PIH…though jury is out and this is current recommendation.
Incompetent cervix and/or cerclage
2-3rd tri bleeding should be persistent to preclude exercise.
Multiple gestation at risk for preterm labor.
Heart disease that is hemodynamically significant (not just floppy mitral valve dz), can always ask your neighborhood cardiologist if significant murmur or sx during preconception counseling.
For relative—IUGR during this pregnancy, any undiagnosed or unevaluated cardiac arrhythmias; poorly controlled DM Type 1 –no mention of type 2, but poorly controlled type 1, in combo w/ pregnancy and exercise, can precipitate severe DKA and fetal demise or miscarriage.
For extremes of weight—extreme morbid obesity w/ hx of extremely sedentary lifestyle (bedridden secondary to wt), or extreme underwt, BMI <12.

34. Warning Signs Vaginal bleeding Dyspnea prior to exertion
Dizziness or presyncopal symptoms
Headache, muscle weakness
Chest pain, calf pain or swelling
Preterm labor, leakage of fluid
Decreased fetal movement
Some of these are relative…but should be discussed w/ patients who are exercising or contemplating exercise during pregnancy, AND should be part of preconception and early pregnancy counseling.

35. Breastfeeding and Exercise
Integral role in post-partum weight loss
Does NOT reduce milk production
Increased lactate levels in breast milk after exercise
Breastfeed before exercise!
Breastfeeding increases post-partum wt loss—we’re all aware of that.
Exercise does not reduce milk production—as many physicians and laymen alike believe—as a matter of fact, there is now research indicating that not only does exercise not decrease milk production, but it may even increase the quantity and quality of breastmilk.
Increased lactate levels—why is this important? Because after exercise, the lactate level in breast milk increases, and many babies don’t like the taste and may decrease their intake during those times. In addition, who wants to exercise when breasts are full? It makes for a very uncomfortable workout. So feed or pump before exercise.

36. Return to Competition No specific recommendations
Guided by symptoms, ability to get back into training
Husbands play a big role
Really no specific recommendations—obviously if you have a c/s the recovery is longer than w/ a vaginal delivery, but most women w/ nl pregnancies and labor can get back into serious training or their regular exercise routine a week or so after delivery. This is where husbands come in—they have a big role.

37. Summary Pregnancy is a good time to establish healthy lifestyle habits
Those adopted during pregnancy could affect a woman’s health for the rest of her life
Be aware of contraindications/warning signs
Almost all women can safely exercise (or begin an exercise program) during pregnancy
Women that cannot exercise truly are the exception rather than the rule. Follow the ACOG guidelines. AND START TO PRACTICE WHAT YOU PREACH!

38. References
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39. Continued…
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