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Exercise and Pregnancy

Physiological Changes

Musculoskeletal:
- Weight gain – due to growing breasts, uterus and fetus
- Increase in lumbar lordosis
- Stretching of abdominal musculature
- Shift in COG à challenge balance
- Increase in joint laxity à higher risk for strains/sprains

Maternal and Fetal Temperature:
- Metabolic rate increases à greater heat production

Cardiovascular:
- Hemodynamic changes à increased blood volume (avg. at term 40-50%)
- Purpose: facilitates maternal and fetal exchanges of respiratory gases, nutrients and metabolites; reduces impact of maternal blood loss at delivery
- Cardiac output increases 30-40%
- Stroke volume increases (~35%) and HR (~15%)
- Cardiac size and position
- Heart is enlarged by hypertrophy and chamber dilation
- Upper displacement of diaphragm causes heart to shift left and anteriorly
- Blood pressure never increases during NORMAL gestation à mid-pregnancy slight decrease in diastolic pressure

Oxygen Demands
- Upper displacement of diaphragm - only slight decrease in total lung capacity
- Due to compensatory increases in transverse and antero-posterior diameters of chest and flaring of the ribs
- Breathing is more diaphragmatic than thoracic
- Oxygen consumption increases gradually (~20% at term)

Energy Demands
- First two trimesters – increase caloric intake ~150 cal./day; third trimester ~300 cal./day
- ***Women who exercise during pregnancy may require more than 150-300 calories per day***

Contraindications
(DO NOT exercise if experiencing the following conditions)
Pregnancy-induced hypertension
Preterm rupture of membranes
Preterm labor during the prior or current pregnancy
Incompetent cervix or cerclage placement
Persistent second- or third-trimester bleeding
Placenta previa
Intrauterine growth retardation

Relative Contraindications
(exercise only with doctors approval)
Chronic hypertension
Thyroid function abnormality
Cardiac disease
Vascular disease
Pulmonary disease

Exercise Benefits
More favorable labor experience
Decreased need for obstetric intervention
Fewer signs of fetal compromise
Subjective experience:
- Less physical discomfort, nausea, decreased perceived exertion during labor
- Higher degree of control

Suggestions:
Safe Exercise Prescription:
- Discuss pre-pregnancy activity level
- Always understand from the beginning – this is MAINTENANCE!
- Intensity, duration and frequency of exercise should not result in pain, shortness of breath or excessive fatigue.
- Hydration – take regular breaks for them to intake fluids
- After first trimester, no exercise in supine position
- Avoid valsalva maneuvers with isometric exercises/weight lifting
- WATCH breathing patterns– (no holding breath/grunting)
- Do not exercise in hot or humid weather
- Most important – common sense and close interaction/communication with trainer and doctor