Pregnancy is a great time to start exercising. This is a time when there is often an increased motivation to maintain or start a healthy lifestyle, while at the same moment the regular frequency of medical appointments facilitates the monitoring of the physical condition and health of the mother and fetus.
Regular physical exercise during pregnancy is associated with numerous benefits:
- Reduced incidence of gestational diabetes
- Reduced hypertensive disorders
- Fewer operative deliveries
- Treatment and prevention of urinary incontinence
- Lumbar pain reduction
- Prevention of excessive weight gain and weight maintenance after the postpartum period
- Reduction of fetal macrosomia
- Stress control
- Reduction of prenatal and postpartum depression, etc.
The fact that pregnant women are not properly informed about this issue, together with various concerns about the possible risks associated with exercise, contribute to abandoning or refusing to start exercise during this period.
A systematic review of 57 articles including meta-analyses, systematic reviews and randomized controlled trials found that exercise was not associated with an increased risk of maternal or perinatal adverse outcomes. Exercise in pregnancy is safe for both mother and fetus, helping to prevent pregnancy-related disorders. The type and intensity of exercise should be adjusted to the woman’s previous fitness level, medical history, and characteristics of the ongoing pregnancy.
Exercise prescription for pregnant women is defined by various international guidelines. In terms of frequency and duration, it is recommended to complete 150–300 minutes of exercise per week, with sessions on most days of the week (≥3 days) of at least 20–30 minutes. In general, greater health benefits are observed with more intense and frequent exercise sessions, in compliance with current international guidelines.
In terms of safety margins, available evidence suggests that low, moderate, and vigorous physical activity is safe. Previously sedentary women should begin their program with light intensity exercise, followed by a more gradual progression. In women with a previously high level of fitness, moderate intensity is recommended, although there is no evidence so far to suggest that vigorous exercise is harmful.
More generally, in pregnancy the resting heart rate increases, but the maximum heart rate decreases. This leads to a reduced reserve capacity of the woman to adapt to exercise-related stress.Measuring the mother’s heart rate is a less accurate way to estimate intensity and to guide exercise – it overestimates the intensity of lower work rates and underestimates the intensity of higher work rates.
In terms of type of exercise, there are activities that have been found to be safe in pregnancy, such as: walking, stationary cycling, aerobic dance, resistance exercises (light weights, body weight, resistance bands), stretching, swimming and water aerobics. Variety in aerobic and resistance exercises yields greater benefits.
Contact sports and sports with an increased risk of injury should be avoided. Exercise in the supine position should be approached carefully, avoiding long periods of training, especially after the first trimester. After 20 weeks, cardiac output is affected by changes in position (especially supine) as the native uterus can press on the abdominal aorta and inferior vena cava, potentially affecting the type of exercise women can do.
In addition, all women should also be aware of the warning signs that will prompt them to stop physical activity: vaginal bleeding, abdominal pain, regular uterine contractions, leakage of amniotic fluid, persistent excessive shortness of breath, dizziness, headache, severe pain in the chest, muscle weakness, pain or swelling in the calf.
Prior to an exercise program, a thorough clinical evaluation should be performed to ensure that there are no medical or obstetric reasons for either avoiding exercise or modifying the exercise routine.
According to the 2019 Canadian Guidelines, absolute contraindications to exercise are: rupture of membranes, preterm labor, unexplained persistent vaginal bleeding, pulmonary embolism, intrauterine growth restriction, multiple pregnancy, uncontrolled type I diabetes, uncontrolled hypertension, uncontrolled thyroid disease and other serious cardiovascular, respiratory or systemic disorders.
In addition, relevant contraindications are: recurrent miscarriages, twin pregnancy after the 28th week, mild/moderate cardiovascular or respiratory disease, symptomatic anemia, malnutrition, eating disorders, and other significant medical conditions.
- Ribeiro MM, Andrade A, Nunes I. Physical exercise in pregnancy: benefits, risks and prescription. J Perinat Med. 2021 Sep 6;50(1):4-17. doi: 10.1515/jpm-2021-0315. PMID: 34478617.
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