Concerns about exercise during pregnancy and its potential connection to miscarriage are common among expectant parents. Understanding the actual causes of miscarriage can help alleviate undue worry and provide a clearer perspective on physical activity during this time.
Understanding Miscarriage Causes
The majority of miscarriages are attributed to chromosomal abnormalities in the developing fetus, especially in the first trimester. These abnormalities typically arise by chance during fertilization, resulting in an incorrect number of chromosomes. For instance, having an extra or missing chromosome can lead to a pregnancy loss. Trisomy 16, where there are three copies of chromosome 16, is a common chromosomal abnormality found in first-trimester losses.
Other less frequent medical reasons can also contribute to miscarriage. These may include specific uterine issues, such as a septate uterus. Hormonal imbalances, certain infections, and clotting disorders like antiphospholipid syndrome are additional medical factors that can impact pregnancy viability. These underlying medical or genetic issues are generally beyond a person’s control and are not typically linked to everyday activities.
Exercise and Miscarriage Risk
Numerous studies have investigated the relationship between physical activity and the risk of miscarriage, consistently showing that routine, moderate exercise does not increase this risk for healthy pregnant individuals. A systematic review and meta-analysis of thirteen randomized clinical trials, involving 3,728 pregnant women, found no significant association between exercise during pregnancy and the occurrence of miscarriage. Similarly, a large six-year prospective cohort study in Denmark involving over 90,000 women found no significant increase in exercise-related miscarriage risk across various gestational ages and exercise durations, including low-intensity and high-intensity activities.
It is important to differentiate between general exercise and extremely high-volume or high-intensity activity, especially for women with specific medical histories. Some research has suggested a potentially higher risk of very early, subclinical pregnancy loss in women with a history of miscarriage who engage in very high levels of physical activity. However, for women with confirmed pregnancies, physical activity and miscarriage risk were found to be unrelated in these studies. This distinction highlights that for most healthy pregnancies, appropriate physical activity remains safe.
Safe Exercise During Pregnancy
Consulting with a healthcare provider before starting or continuing an exercise routine during pregnancy is a first step. This ensures that any individual health conditions or pregnancy complications are considered. The American College of Obstetricians and Gynecologists (ACOG) generally recommends at least 150 minutes of moderate-intensity aerobic activity each week for healthy pregnant individuals. This can be achieved through 30-minute workouts five days a week or shorter 10-minute sessions spread throughout the day.
Recommended activities that are generally safe include:
- Brisk walking
- Swimming
- Water workouts
- Stationary cycling
- Modified yoga or Pilates
When exercising, use the “talk test” to gauge intensity; you should be able to hold a conversation but not sing. Proper hydration is important, so drink plenty of water before, during, and after workouts.
Certain activities should be modified or avoided during pregnancy. Avoid high-risk activities such as:
- Contact sports like basketball or soccer
- Activities with a high risk of falling, including horseback riding, downhill skiing, or outdoor cycling
- Scuba diving
- Skydiving, due to changes in oxygen levels
After the first trimester, avoid exercises that involve lying flat on the back, as this position can restrict blood flow to the uterus. Also, avoid overheating, especially in the first trimester, by wearing loose clothing and exercising in temperature-controlled environments.
When to Consult a Doctor
While exercise is generally safe during pregnancy, be aware of certain warning signs that warrant immediate medical attention. These signs are not necessarily indicative of exercise causing a miscarriage but are general concerns during pregnancy. If you experience vaginal bleeding, persistent abdominal or pelvic pain, or fluid leaking from the vagina, stop exercising and contact your healthcare provider.
Other symptoms that require medical consultation include:
- Dizziness, lightheadedness, or feeling faint
- Unusual shortness of breath, chest pain, heart palpitations, or a racing heartbeat
- Sudden swelling in the face, hands, or feet
- Calf pain or swelling
- A noticeable decrease in fetal movement
These signs require prompt medical evaluation.