Physical Activity and Pregnancy

Original Editor - Mariam Hashem

Top Contributors - Nicole Hills, Mariam Hashem, Wendy Walker, Lucinda hampton and Kim Jackson  

Introduction

Physical activity is defined as any bodily movement produced by skeletal muscles that result in energy expenditure.[1] Exercise is a subset of physical activity that is planned, structured, repeated and has a final or an intermediate objective to the improvement or maintenance of physical fitness.[1]

Physical activity is considered safe and beneficial for pregnant women without contraindications to exercise. Pregnancy can be seen as a great time for lifestyle modifications. Moderate intensity exercises are proven to be beneficial for both mother and fetus in most pregnancies with the necessary modifications.[2]

Exercise improves the health and wellbeing of both the mother and infant during pregnancy and in the postpartum period. Pregnancy and the postpartum period are viewed as “teachable moments” where women are motivated to change their habits to improve the health of their babies and themselves. [3] This unique period of time provides an opportunity for health care professionals, specifically physiotherapists, to educate women on the importance of adopting healthy lifestyle interventions, which includes exercise. [3]

Current recommendations

All women without contraindications (see below) should be physically active during pregnancy. The following six recommendations are from the Canadian guideline for physical activity throughout pregnancy[4] that was informed by an extensive systematic review and input from pregnant women, exercise professionals and obstetric health care providers.

  1. All women without contraindication should be physically active throughout pregnancy
  2. Pregnant women should accumulate at least 150 minutes of moderate-intense physical activity each weak to achieve health benefits and a reduction in pregnancy complications
  3. The physical activity should be accumulated over 3 days per week (being active daily is encouraged)
  4. A combination of aerobic and resistance training achieves greater benefits and including yoga and/or gentle stretching is encouraged
  5. Pelvic floor muscle training (PFMT) should be performed on a daily basis to reduce the risk of urinary incontinence (refer to a pelvic floor physiotherapist for assessment and PFMT when possible)
  6. Pregnant women who become light-headed, nauseated or feel unwell when exercising on their backs should modify their exercise programs to avoid the supine position.[4]

Contraindications

During pregnancy women who present with absolute contraindications to exercise may continue with their usual daily activities but should avoid moderate and vigorous activities.[4] Women with relative contraindications should discuss their potential participation in these activities with their obstetric care provider prior to beginning or continuing with their exercise programs.[4]

Absolute contraindications

  • Ruptured membranes
  • Premature labour
  • Unexplained PV bleeding
  • Placenta praevia after 28 weeks
  • Pre-eclampsia
  • Incompetent cervix
  • Intrauterine growth restriction
  • Higher-order multiple pregnancy (e.g., twins, triplets etc.)
  • Uncontrolled high blood pressure, type 1 or type 2 diabetes or thyroid disease
  • Other serious cardiovascular, respiratory or systemic disorders[4]

Relative contraindications

  • Recurrent pregnancy loss
  • Gestational hypertension
  • A history of spontaneous preterm birth
  • Mild/moderate cardiovascular or respiratory disease
  • Symptomatic anaemia
  • Malnutrition
  • Eating disorder
  • Twin pregnancy after the 28th week
  • Other significant medical conditions[4]

Prenatal exercise safety

Physiotherapists should educate pregnant women on specific safety precautions, activities to avoid and on signs and symptoms that indicate they should stop exercising and consult their healthcare provider.[4]

Safety precautions

Pregnant individuals should be advised to:

  • avoid physical activity in excessive heat, especially when high humidity levels are present
  • avoid activities that involve physical contact (e.g., sports such as hockey, soccer (football) or danger of falling (e.g., non-stationary cycling, skiing, snowboarding).
  • avoid scuba diving
  • avoid physical activity at high altitude (>2500 m) if they are a 'lowlander' (ie, living below 2500 m). Individuals considering physical activity above those altitudes consult an obstetric care provider who is knowledgable about the impact of high altitude on maternal and fetal outcomes.
  • consult their obstetric care provider if considering athletic competition or exercising significantly above the recommended guidelines. Individuals should seek supervision from an obstetric care provider with knowledge of the impact of high-intensity physical activity on maternal and fetal outcomes.
  • maintain adequate nutrition and hydration (e.g., drink water before, during and after physical activity.
  • understand the reasons to stop physical activity and consult a qualified healthcare provider immediately if any adverse reactions to exercise occur (see below).[4]

Adverse reactions to exercise

Women should be advised to stop exercising and consult their healthcare provider immediately if any of the following occur:[4]

  • persistent excessive shortness of breath that does not resolve with rest
  • severe chest pain
  • regular and painful uterine contractions
  • vaginal bleeding
  • persistent loss of fluid from the vagina indicating the rupture of the membranes
  • persistent dizziness or faintness that does not resolve on rest
  • decreased fetal movement[4]

Benefits of physical activity during pregnancy

Exercise and weight management


Weight gain during pregnancy is known as gestational weight gain (GWG). Women who begin pregnancy:

  • underweight should be expected to gain 12.5-18kg over the course of their pregnancy
  • normal weight should gain between 11.5-16kg
  • overweight should gain 7-11.5 kg and
  • obese should gain between 5-9 kg[5].
A high percentage of women exceed the recommended weight.[6] Excessive GWG is associated with a high-risk of developing gestational diabetes mellitus (GDM), hypertension[7], having a cesarean delivery and postpartum weight retention.[8] Regular physical activity during pregnancy can reduce GWG by an average of 6.8 pounds compared to women who do not exercise regularly.[9] A recent randomized control trial (RCT) suggests behavioural-lifestyle intervention supported by a smartphone app among pregnant women improved dietary, physical activity, and motivation outcomes[10].

Exercise and cardiac and respiratory fitness

Pregnancy is accompanied by many cardiac and respiratory changes that begin during the fifth week of gestation and last until about a year after delivery[11], Cardiac output and blood volume increase up to 40%.[12] [13] Tidal volume and oxygen consumption (VO2) also increases to supply the oxygen requirements of the fetus.
   

Aerobic exercise such as swimming, static cycling and general floor exercise programs, at least two to three times per week is recommended to maintain cardiovascular fitness, reduces ventilatory demands, enhances the breathing pattern and eventually inhibits exertional breathing problems occur in pregnancy.

Exercise and psychological well-being

Pregnancy can also be a time of major emotional changes. Many women suffer alterations in mood and even prenatal depression. Recent studies have estimated the prevalence of depression during pregnancy to be between 10% and 20%[14][15].

The women who keep fit during pregnancy are more relaxed and cope better with the emotional and physiological strains of pregnancy, this is attributed to a number of positive effects from exercise such as weight management, better body image and self-esteem, improved sleep, and increased energy levels.

Exercise is also proven to be effective in treating antenatal depression[16].

Low back pain

Pregnant women may develop an increase in lumbar lordosis, which has been shown to contribute to the prevalence (50%) of low back pain in pregnant women.[17] A general whole-body exercise program and lumbar stabilisation exercises can help to reduce the intensity of back pain.[18][19]

Labour outcomes

Pregnant women who maintain a regular exercise routine may experience less pain and shorter labour.[20] This is attributed to the exercise effect on inducing metabolic and hormonal changes that may impact uterine contractility and endurance.[21] Exercises during pregnancy are also associated with reduced need for Cesarean section.[22]

Urinary incontinence  

Pelvic floor strengthening exercises during pregnancy are helpful in prevention and reducing the symptoms of urinary incontinence.[23]

Diastasis recti abdominis

There is no evidence to support the need to treat or prevent diastasis recti abdominis during pregnancy.[24]

Exercise recommendations

Swimming in pregnancy.jpeg

The American College of Sports Medicine (ACSM) recommends reviewing the overall health, obstetric, and medical risks before prescribing an exercise program to a woman who is pregnant. In the absence of contraindications, a pregnant woman should be encouraged to engage in regular, moderate-intensity physical activity.[25]

Pregnant women are encouraged to spend 30 minutes or more of moderate-intensity physical activity on most, and preferably all days of the week. Moderate-intensity physical activity is defined as an activity with an energy requirement of 3-5 metabolic equivalents (METS). For most healthy adults, this is equivalent to brisk walking at 3-4 mph. After the 13th week of pregnancy, about (300 kcal) per day are required to meet the metabolic needs of pregnancy. this energy requirement is increased further when daily energy expenditure is increased through exercise, especially with weight-bearing exercises, such as walking. Proper hydration and subjective feelings of heat stress are very important. The supine position should be avoided as much as possible during rest and exercise after the first trimester, as it can obstruct venous return. Motionless (static) standing should be avoided as it is associated with a significant decrease in cardiac output.

Of note:

  1. Exercises that use large muscle groups in a continuous rhythmic manner are beneficial and have not been associated with adverse effects eg aerobic exercises, walking, hiking, jogging/running, aerobic dance, swimming, cycling, rowing, cross country skiing, skating, dancing and rope skipping (extra caution should be taken with activities that increase the risk of falls).
  2. Resistance Training (low weights with multiple repetitions) is safe and effective during pregnancy.
  3. The recommended intensity of physical activity should be 60-90% of maximal heart rate, and rating of perceived exertion should be 12-14 ( somewhat hard) on the 6-20 scale for pregnant women who did not engage in regular exercise before pregnancy. Women who were regular exercisers before pregnancy and who have uncomplicated, healthy pregnancies should be able to engage in high-intensity exercise programs. Non-stress fetal heart testing and ultrasound to assess fetal growth should be considered if clinically indicated in high-intensity exercisers.[25]

Physical activities effects on the fetus and the newborn

Exercise is not associated with birth weight reduction[26] and has been found to reduce the risk of preterm birth.[2]. Exercise can boost the neuro-behavioral profile and orientation level of the newborn; they are more alert and interested in their surroundings, and less demanding on their mothers. Also, babies of physically active pregnant women are lighter and leaner than offspring from nonphysically active pregnant women.[2]

A study that compared placental growth and morphometric measurements found faster placental growth rate, and greater scores on the morphometric indexes of placental function with exercising pregnant women.[27]

Sedentary lifestyle during pregnancy

A sedentary lifestyle during pregnancy has been associated with:

Obesity during pregnancy carries elevated risks for major complications such as:[28]

  • More likely to suffer spontaneous abortions.
  • Higher risk of neural tube defects which include cleft palate, spina bifida, and hydrocephalus.
  • At risk for gestational diabetes, preeclampsia, sleep apnea, macrosomia, preterm birth and even stillbirth (the higher the women's BMI, the greater the risk) 

Resources

[29]

2019 Canadian guideline for physical activity during pregnancy[4]

American College of Obstetricians and Gynecologists committee opinion on physical activity and exercise during pregnancy and postpartum[30]

Exercise and pregnancy in recreational and elite athletes a 5 part series by Bø and colleagues (2016):

Summary of the international guidelines for physical activity after pregnancy[35]

The Motivate2Move website, created by Wales Deanery, has a useful page on Exercise During Pregnancy.

References

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