In the past, pregnant women were often advised to avoid physical exercise during pregnancy because of the risk to the fetus. At the same time, they were advised to increase their calorie intake during pregnancy. Because of these misguided recommendations, women often retained some of the weight they gained during pregnancy later on. Higher maternal body weight is linked to a higher birth weight and contributes to the intergenerational spread of obesity. As a result, pregnancy has contributed to the global obesity epidemic and to other fetal and maternal conditions, some of which have long-term consequences.
The American College of Obstetricians and Gynecologists (ACOG) emphasizes that a sedentary lifestyle poses a major risk to women’s health. They published their exercise guidelines for pregnancy back in 1985, and the latest update was published in 2015. Unfortunately, only a small number of women reach a satisfactory level of physical activity during pregnancy, partly because they are unsure about the type and amount of exercise that can be done during pregnancy.
Is exercise during pregnancy safe?
Doctors have “traditionally” been concerned about the possibility of fetal stress and preterm birth that could be caused by physical exercise during pregnancy. However, a recent meta-analysis including 2,059 women shows that in women with a normal body weight and no pregnancy complications, moderate-intensity aerobic exercise (stationary cycling, water aerobics, aerobic dance) and strength training (60%–80% of maximum heart rate; 220 minus age in years), 3 to 4 days a week (35–90 min per session; 60 min on average), started late in the first trimester (between weeks 8 and 13) or in the second trimester (between weeks 16 and 22) and continued until the end of pregnancy, did not increase the risk of preterm birth (before <37 weeks) and did not increase the risk of low birth weight.
Another question that comes up is whether exercise is also safe for women who did not exercise and were not physically active before pregnancy.
Contrary to previous beliefs, pregnancy can now be defined as an ideal time not only to continue, but also to start an active lifestyle. Evidence from a recent study of 634 previously sedentary women shows that a combination of moderate-intensity aerobic dance and muscle-strengthening exercises (<70% of maximum heart rate; 3x per week for 50–55 min; from weeks 9–11 until the end of pregnancy) does not compromise the well-being of the mother or the fetus in terms of gestational age, does not affect the type of delivery, does not affect the incidence of preterm birth, does not affect birth weight, nor neonatal head circumference, APGAR score, or umbilical cord blood pH.
Exercise is also considered safe for women with risk factors such as chronic hypertension, diabetes, or overweight/obesity. A meta-analysis of 722 women with at least one of these conditions showed that moderate-intensity aerobic exercise (walking, stationary cycling, aerobic dance, water exercise) (70% of heart rate reserve—”maximum heart rate minus resting heart rate”) and strength training are safe for the fetus.
Pregnancy is a time of major physical and emotional changes, but physical activity and movement should still be a normal part of everyday life during pregnancy. In 2002, the American College of Obstetricians and Gynecologists stated that 30 minutes or more of moderate physical activity per day, on most days of the week, is recommended for pregnant women, provided there are no medical or other pregnancy-related complications. Moderate exercise means a woman should be breathing through her mouth rather than her nose, but still be able to talk without difficulty (the so-called talk test) (Šćepanović, n.d.).
The goal of physical activity during pregnancy is to maintain or moderately improve fitness, and after birth to restore and then improve fitness again. Women have different fitness levels before pregnancy. The fitness level they want to achieve during pregnancy and after birth also varies from woman to woman. That is why women should be given a questionnaire before joining an exercise program (Šćepanović, n.d.).
Benefits of exercise during pregnancy.
According to a 2009 report by the U.S. Institute of Medicine, excessive weight gain during pregnancy is common across all categories of women: 19.5% of underweight women gained approx. 18 kg, 38.4% of women with normal body weight gained approx. 16 kg, 63.0% of overweight women gained approx. 11.5 kg, and 46.3% of obese women gained approx. 9 kg. A major benefit of exercise during pregnancy is preventing excessive weight gain. A meta-analysis of multiple studies (7,096 participants) provided high-quality evidence that moderate aerobic exercise (walking, dancing, aerobics), with or without diet, is associated with a significantly reduced risk of excessive gestational weight gain (average risk ratio 0.80 [95% confidence interval 0.73–0.87]). Exercise during pregnancy is also associated with a lower risk of the following conditions: fetal macrosomia, diabetes, preeclampsia, cesarean section, low back pain, pelvic girdle pain, and urinary incontinence.
During exercise, a pregnant woman should learn to:
- Correctly activate the deep abdominal muscle, the transversus
- Correctly perform pelvic floor muscle exercises
- Breathe correctly
- Lift loads correctly
- Get up correctly
- Adopt correct posture
- Body position and a functional pattern for effective bowel movements
- Learn to observe herself
WHICH EXERCISE IS RECOMMENDED?
GENERAL EXERCISE RECOMMENDATIONS
According to the latest ACOG guidelines, it makes sense to encourage all pregnant women without obstetric or medical problems to follow the same exercise guidelines as women who are not pregnant. This means including moderate-intensity aerobic exercise and muscle strengthening for at least 20 to 30 minutes a day (see TABLE), on most days of the week. Most high-quality studies used aerobic exercise and strength exercises starting after the first prenatal visit (weeks 9–12) and lasting almost until the due date (weeks 38–39). Clinical trials have not been able to prove the benefits of yoga and Pilates, which many people recommend today. However, yoga is believed to be effective for improving mental health and reducing pain. The intensity of each workout must be individualized and can be monitored using the Borg Rating of Perceived Exertion (RPE) scale (lowest score 6 [very, very light effort]; highest score 20 [very, very hard effort]). According to ACOG guidelines, pregnant women should exercise at moderate intensity (RPE 13–14).
A more practical method, also recommended by ACOG, is to monitor exercise intensity using the “talk test”—as long as a woman can talk while exercising, the exercise should not be too strenuous for her.
- Before starting exercise, a pregnant woman should always warm up gradually and cool down after exercise.
- She should never exercise right after a large meal (there should be 2 hours between a larger meal and the start of an exercise program). She should also make sure her stomach isn’t completely empty, as she would quickly become hungry during exercise and wouldn’t be able to exercise safely and effectively.
- She should not exercise in an extremely hot, cold, humid, or poorly ventilated room.
- She should not exercise if she has an elevated body temperature or is acutely ill.
- She should wear light, breathable clothing. Her footwear should be comfortable and non-slip.
- During exercise, she must replace fluids regularly. She should drink a few sips of water or a non-alcoholic, non-carbonated drink.
- The type of exercise should be chosen appropriately. A pregnant woman should avoid learning new sports and high-risk sports. She should do exercise/sport that she already knows and is comfortable with.
- Exercise intensity should match the pregnant woman’s fitness level, i.e., such that she can still talk during exercise. It’s important to listen to her body. Moderate-intensity exercise is most recommended.
- Exercise duration should be around 45–60 minutes.
- As pregnancy progresses, the pregnant woman should reduce exercise intensity and duration, as well as the load weight and the number of repetitions and sets.
- Heart rate should not exceed 140 beats/min, or 60–70% of max heart rate.
- One rest day is recommended between exercise sessions.
- She should avoid exercises with jumping and excessive loading of the abdominal muscles.
- She should be moderate and careful with stretching exercises.
- She should avoid ballistic exercises such as bouncing, sliding, rocking, and thrusting.
- After week 16 of pregnancy, she should avoid exercises where she lies on her back for more than 5 minutes at a time.
- Body position should be changed slowly, especially when moving from a low to a high position and vice versa.
- If she has issues with involuntary urine leakage, pain in the spine and pelvis and pubic symphysis, or a pathological separation of the rectus abdominis muscles, she should seek help from a gynecologist, who will refer her to a physiotherapist.
- If she is regularly physically active, she should consume an additional 200 to 300 kcal per day.
- She should never exercise alone or in a dangerous environment.
- She should watch for warning signs to stop exercising.
- During exercises, she should not hold her breath, but breathe evenly and relaxed.
- She should pay attention to correct posture during exercise and in everyday activities (Pogorevc 2012 after ACOG, 2002, RCOG, 2006; Drev and Drglin, 2010).
CONTRAINDICATIONS
Women should exercise in a pleasant and comfortable environment, ensure hydration, avoid high humidity and high temperatures, not exercise on an empty stomach, and prevent hypoglycemia. Exercise should be stopped when warning signs and specific symptoms occur, such as vaginal bleeding, regular or painful contractions, leakage of amniotic fluid, dyspnea before exertion, dizziness, headache, chest pain, muscle weakness affecting balance, calf pain, or swelling.
Higher-intensity exercise (above 90% of maximum heart rate) is not recommended, as it can increase the risk of overheating or dehydration and divert a large amount of blood to the muscles, affecting placental perfusion and potentially endangering the fetus.
Long-distance running, frequent lifting of heavier weights, or intense isometric exercises are also not recommended. The latter often involves repeated Valsalva maneuvers, which during this period pose a risk to placental blood flow and fetal heart rate (by increasing arterial and intra-abdominal pressure); it can also harm the pelvic floor, as it increases the risk of urinary and anal incontinence or pelvic organ prolapse.
Exercises performed lying on the back (face up) should be avoided from the second trimester until birth. Exercising in this position during this period can cause aortocaval compression, which can lead to hypotension and reduced cardiac output, which in turn can reduce fetal blood flow. Avoiding all types of exercise except movement and walking is recommended in the following conditions: hemodynamically significant heart disease, restrictive lung disease, incompetent cervix, bleeding in the second or third trimester, placenta previa after week 26, where there is a risk of membrane rupture (with the onset of uterine contractions and in multiple pregnancy where there is a risk of preterm birth), preeclampsia or pregnancy-induced hypertension, and in cases of severe anemia. ACOG guidelines recommend allowing patients with these conditions to move and walk to prevent venous thrombosis, which is more common during pregnancy.
Absolute contraindications:
- Elevated BP (preeclampsia)
- Fetal distress
- Threatened preterm labor (shortened cervix)
- Placenta previa
- PROM (PPROM)
- Persistent bleeding in the second and third trimester
- Multiple pregnancy
- Uncontrolled type 1 diabetes, thyroid disease, other serious cardiovascular, respiratory, or systemic diseases
- Acute infectious diseases
Relative contraindications:
- miscarriage or preterm birth in previous pregnancies,
- twin pregnancy after week 28,
- eating disorders (anorexia, bulimia),
- chronic bronchitis
- IUGR
- anemia or iron deficiency (Hb<100 g/L),
- mild and moderate chronic cardiovascular and respiratory diseases (e.g., high blood pressure—but controlled, arrhythmias, bronchial asthma, and chronic bronchitis),
- extremely sedentary lifestyle,
- smoking (more than 20 cigarettes a day)
- orthopedic limitations,
- poorly controlled thyroid disease,
- obesitas (obesity),
- poor nutrition or eating disorders,
- poorly controlled seizures (ACOG, 2002; Kebler Zaletel, 2012).
When should exercise be stopped?
- Vaginal bleeding
- Difficulty breathing at rest
- Dizziness and lightheadedness
- Headache, visual disturbances
- Back or pubic pain
- Kidney pain
- Vena cava syndrome
- Chest pain and palpitations
- Muscle weakness
- Calf pain or swelling
- Contractions
- Reduced fetal movement
- Leakage of amniotic fluid (ACOG, 2002).
FITT PRINCIPLE (frequency, intensity, time, type of exercise)
- Moderate-intensity, aerobic-type activity
- Heart rate should not exceed 140 beats per minute, or 60–70% of max heart rate
- Regular exercise 3–4x per week, lasting 25–60 minutes
- One rest day is recommended between sessions
A pregnant woman should not exhaust herself; care should be taken that exercise is not too intense. She should not become overly out of breath and must be able to hold a normal conversation during exercise. The surface for physical activity should be wooden or cushioned floors, which reduce impact and provide reliable, non-slip support for the feet. Weather conditions should also be considered (Kebler Zaletel, 2012).
Why should a pregnant woman be active?
- Maintaining good physical fitness and flexible, firm, and strong muscles helps make pregnancy easier, improves childbirth, and supports more active participation.
- It reduces or eases pregnancy discomforts (edema, nausea, constipation, nausea, varicose veins, muscle cramps, BP….) and helps regulate body weight, supports correct posture, and prevents pain.
- It maintains and strengthens overall fitness, joint mobility, and muscular endurance and strength.
- It also has a positive effect on fetal development.
- Faster return to pre-pregnancy shape.
Women learn (relaxation) breathing techniques, get to know their body and its response to positions better, and learn to tense some muscles while relaxing others at the same time (Drev, Drglin, 2010).
Effect on the fetus
- Special attention in high-intensity exercise to blood circulation.
- During activity, the fetal heart rate increases so it gets more oxygen.
- With moderate activity, fetal movement temporarily increases, which indicates the fetus is not in distress.
- Smaller weight gain (approx. 300 g), which is still within normal limits.
QUALITIES OF A GOOD INSTRUCTOR
A properly trained instructor guides a woman safely through exercise during pregnancy and takes appropriate action or gives advice if problems arise. Pregnant women who attend group exercise classes sometimes don’t know whether the instructor has specific knowledge related to pregnancy and exercise during pregnancy, and they cannot verify it. This is why it is important to highlight the need to establish a mechanism that ensures that pregnancy exercise is led only by a suitably qualified instructor (Drev and Drglin, 2010).
The instructor must:
- understand and know all limitations related to high-risk and healthy pregnancy,
- be able to notice and assess changes and the pregnant woman’s abilities,
- distinguish beneficial from harmful exercise,
- stop exercise in time,
- be able to give appropriate and specific advice, perform and teach pregnant women different breathing techniques and relaxation methods,
- prevent possible pain and injuries, dehydration and overheating, and lack of oxygen for the fetus,
- know ergonomic principles and correct posture and positions,
- safely and correctly structure strength, endurance, and flexibility exercises,
- ensure that every pregnant woman feels safe, accepted, and relaxed.
- Before starting an exercise program, provide a questionnaire about your health status.
- perform a test for abdominal muscle separation,
- perform a pain assessment.
A pregnant woman should not join programs intended for non-pregnant women. The program can be adapted for her by a professionally trained aerobics instructor. If such an instructor is not available, she should take part in low-intensity groups and avoid lying on her back, jumping, and maximal stretching (Slovenc, 2009).
Pregnancy has long since stopped being just a state of childbirth and immobility; an active lifestyle during pregnancy is safe and beneficial. Most health and scientific organizations encourage physical activity at all stages of life, including pregnancy.
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