Exercise in Pregnancy

Jennifer Hale, M.D.

Valley Baptist Family Practice Residency

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 !

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

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

Fun Facts

• ↑ HDL, ↓ triglycerides

• ↓ blood pressure

• Improved endothelial function

• Improved glycemic control

• ↓ risk of CAD

• ↑ longevity

• ↓ cancer risk

• ↓ proinflammatory cytokines

• ↓ oxidative stress

• Improved psychological well-being

Continued…

• ↑ energy

• ↓ weight gain

• ↑ strength/endurance

• ↓ back pain

• Improved sleep

• Improved sense of well-being

• ↓ risk GDM

• ↓ risk pre-eclampsia

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

(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

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

Where We’ve Come From

Zahereiva et al.• From 1952-1972

-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.”

Physiologic Adaptations during Pregnancy and Exercise

• Cardiovascular

• Pulmonary

• Thermoregulatory Control

• Musculoskeletal

Cardiovascular

Rest

• ↑ plasma volume

• ↑ baseline heart rate

• ↑ cardiac output

• ↑ stroke volume

• ↓ systemic vascular resistance

Exercise

• ↓ BP

• ↓ vagal tone as pregnancy advances

• Blunted HR response to exercise

Continued…

ACOG Recommendations:

• Avoid exercise in supine position after 1st trimester

• Avoid prolonged standing

• HR > 140 now allowed

Pulmonary

Rest

• ↑ tidal volume

• ↑ oxygen uptake

• ↑ resting oxygen requirements

• ↑ work of breathing

Exercise

• ↓ oxygen available for exercise

• ↓ maximum performance

• SOB with less exertion

Continued…

ACOG Recommendations:

• No specific recommendation, except…

• Exercise intensity should be based on symptoms

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?

Continued…

• Clap et al.- 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

Continued…

ACOG Recommendations:

• Avoid hot, humid conditions, high altitudes

• Wear appropriate clothing

• Stay hydrated!

• Innate physiologic protection against hyperthermia

Musculoskeletal

Rest

• 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?

Continued…

ACOG Recommendations:

• No specific guidelines

• Adjust activity based on gestational age, symptoms

• Stretching/strengthening exercises

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

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 35%- light/mod vs. vigorous 24% vs. 54%- brisk walking (≥ 3mi/hr) 30-33%- vigorous exercise year prior 60%- stair climbing (1-4 flights/d) 29%

Other Benefits

• No ↑ risk of miscarriage

• Possible ↓ risk preterm birth

• ↓ risk of cesarean section ?

• Faster recovery post-partum

• Labor duration ?

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

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

Exercise Prescription

Where to Start:

- Gather information for History & Physical Exam

- Gestational age

- Goals

- Grade

- “F I T T”

“F I T T”

• Frequency- “most days of the week”

• Intensity-THR vs. Borg scale

• Type-walking/biking/running/swimming

• Time-30-90min/day

Borg Scale

“F I T T”

• Frequency- “most days of the week”

• Intensity-THR vs. Borg scale

• Type-walking/biking/running/swimming

• Time-30-90min/day

Sample

Sedentary Recreational Elite

Frequency ≥ 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

Continued…

• Stretching

- static, not ballistic

- hold for at least 1min

• Weight Lifting

- 10-15 repetitions

- low weight

NutritionFour F’s:

• Food ↑ 150cal/day 1st - 2nd trimester ↑ 300cal/day 3rd trimester

• Fluids ↑ 30ml/day1 lb = 500cc

• Fe (Iron)

• Folate

Contraindications

Absolute

• 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

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

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!

Return to Competition

• No specific recommendations

• Guided by symptoms, ability to get back into training

• Husbands play a big role

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

QUESTIONS?

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Continued…

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