Physical Activity and Pregnancy

Original Editor - Mariam Hashem

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Introduction

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 to vigorous physical activity (MVPA) are proven to be beneficial for both mother and fetus in most pregnancies with the necessary modifications.

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. 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.

Current recommendations

In women, physical activity during pregnancy and the postpartum period confers benefits for the following maternal and fetal health outcomes:

• Decreased caesarean births and operative vaginal delivery
• Better postpartum recovery
• Prevention of postpartum depression
• Prevention of excessive gestational weight gain (GWG)
• Reduced risks of obesity in pregnancy
• Reduced pregnancy complications such as pre-eclampsia, gestational hypertension, gestational diabetes (GDM), fetal marcosomia, low birth weight.

The following recommendations are from the WHO 2020 guideline - all pregnant and postpartum women (without contraindications) should aim to:

• Undertake regular physical activity throughout pregnancy and post partum period;
• Accumulate at least 150 min of moderate-intensity physical activity throughout the week. For substantial health benefits, it is best to incorporate a variety of aerobic (eg. brisk walking, swimming, stationary cycling, low-impact aerobics, jogging, modified yoga and modified Pilates) and resistance training activities (body weight exercises eg. squats, lunges, push-ups). ;
• Incorporate a variety of aerobic and muscle-strengthening activities. Adding gentle stretching may also be beneficial.

In addition:

• Women who, before pregnancy, habitually engaged in vigorous-intensity aerobic activity or who were physically active can continue these activities during pregnancy and the postpartum period.
• If pregnant and postpartum women are not currently meeting these recommendations, doing some physical activity will bring health benefits. They should start with small amounts of physical activity and gradually increase frequency, intensity and duration over time. Pelvic floor muscle training (Kegel's exercise) may be performed on a daily basis to reduce the risk of urinary incontinence.
• Pregnant and postpartum women should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.

Additional on safety considerations when undertaking physical activity for pregnant women are:

• Avoid physical activity during excessive heat, especially with high humidity;
• Stay hydrated by drinking water before, during and after physical activity;
• Avoid participating in activities which involve physical contact, pose a high risk of falling or might limit oxygenation (such as activities at high altitude, when not normally living at altitude);
• Avoid activities in supine position after the first trimester of pregnancy as this can lead to decreased cardiac output, aortal-caval compression and hypotension;
• Pregnant women considering athletic competition or exercising significantly above the recommended guidelines should seek supervision from a specialist healthcare provider;
• Pregnant women should be informed by their healthcare provider of the danger signs for when to stop, or limit physical activity and to consult a qualified healthcare provider immediately if they occur.

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. 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.

Absolute contraindications

• Ruptured membranes
• Active preterm labour
• Unexplained PV bleeding
• Placenta praevia after 28 weeks
• Severe 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
• Uncontrolled or severe arrhythmia
• Other serious cardiovascular, respiratory or systemic disorders

Relative contraindications

• Mild/moderate cardiovascular or respiratory disease
• Well-controlled type 1 diabetes
• Mild pre-eclampsia
• Preterm premature rupture of membranes
• Untreated thyroid disease
• Multiple nutrient deficiencies/ malnutrition
• Symptomatic severe eating disorder
• Placenta previa after 28 weeks
• Moderate to heavy smoking (>20 cigarettes per day)
• Other significant medical conditions

Prenatal exercise safety

Physiotherapists should educate pregnant women on specific safety precautions during exercise, activities to avoid, and when to consult their healthcare provider.

Safety precautions (see above)

Adverse reactions to exercise

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

• 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, syncope or faintness that does not resolve on rest
• decreased fetal movement
• muscle weakness affecting balance
• calf pain or swelling

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.

A high percentage of women exceed the recommended weight. Excessive GWG is associated with a high risk of developing gestational diabetes mellitus (GDM), hypertension, having a cesarean delivery and postpartum weight retention. Regular physical activity during pregnancy can reduce GWG by an average of 6.8 pounds compared to women who do not exercise regularly. 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.

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, Cardiac output and blood volume increase up to 50%.  Tidal volume and oxygen consumption (VO2) also increases to supply the oxygen requirements of the fetus.
   

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%.

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.

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. A general whole-body exercise program and lumbar stabilisation exercises can help to reduce the intensity of back pain.

Labour outcomes

Pregnant women who maintain a regular exercise routine may experience less pain and shorter labour. This is attributed to the exercise effect on inducing metabolic and hormonal changes that may impact uterine contractility and endurance. Exercise during pregnancy has also been associated with reduced risk for Cesarean birth.

Urinary incontinence  

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

Diastasis recti abdominis

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

Exercise recommendations

American College of Obstetricians and Gynecologists 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.

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 2-5 mph or a self-reported rating of 12-13 (somewhat hard) on the Borg scale of perceived exertion. 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.

FITT Recommendations for Pregnancy

• Frequency: 3 or more days a week for aerobic activities and 2-3 non-consecutive days per week for resistance activities.
• Intensity: moderate-intensity (12-13 on the 6-20 Borg scale) for aerobic activities, resistance activities should be performed to the point of moderate fatigue (8-10 reps or 12-15 reps). Begin with low weights with multiple repetitions.
• Time: 30 minutes of moderate-intensity aerobic activities, 2-3 sets of resistance exercises focusing on major muscle groups. (beginners should start with 1 set and progress as able)
• Type: 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).

Physical activities effects on the fetus and the newborn

Exercise is not associated with birth weight reduction and has been found to reduce the risk of preterm birth.. 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 non-physically active pregnant women.

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.

Resources

e FIT and Safe ADVICE FOR MOTHERS-TO-BE AND NEW MOTHERS

2019 Canadian guideline for physical activity during pregnancy

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

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

• Part 1: Exercise in women planning pregnancy and those who are pregnant
• Part 2: Effect of having exercised (physical fitness) on labour and neonatal/fetal outcomes
• Part 3: Guidance on returning to exercise in the postpartum period
• Part 4: Future research directions for athletes and pregnancy
• Part 5: Recommendations for health professionals and active women

Summary of the international guidelines for physical activity after pregnancy

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