It is a common worry for expectant parents whether physical activity during early pregnancy could lead to a miscarriage. Understanding the underlying causes of miscarriage and appropriate exercise guidelines helps alleviate these anxieties.
Common Miscarriage Causes
Miscarriages, the loss of a pregnancy before 20 weeks of gestation, are common, with about 10-20% of known pregnancies occurring this way. Most miscarriages, especially in the first trimester, are due to chromosomal abnormalities. These issues, like missing or extra chromosomes, prevent proper fetal development. These genetic errors, accounting for 50% to 85% of early miscarriages, happen by chance during fertilization or early embryonic development.
Less common causes include structural abnormalities within the uterus, infections like rubella or listeriosis, or hormonal imbalances. Maternal health conditions such as uncontrolled diabetes, severe kidney disease, or immune system disorders also increase risk. Lifestyle factors like smoking, alcohol consumption, or drug use also contribute. Most miscarriages are not caused by something the pregnant person did or did not do.
Exercise and Miscarriage Risk
Scientific evidence indicates that regular, moderate exercise does not increase the risk of miscarriage in early pregnancy. The misconception that exercise causes miscarriage stems from miscarriages being most common in the first trimester, a period when many naturally reduce activity due to symptoms or fear. This can lead to a false association between activity and loss.
The developing fetus is well-protected by the uterine walls, amniotic fluid, and placenta. Maintaining physical activity throughout pregnancy offers benefits such as improved mood, increased energy, better fitness, and reduced back and pelvic pain. Exercise can also lower the risk of gestational diabetes and preeclampsia, and prepares the body for labor.
Some studies have suggested a potential link between high-impact, vigorous exercise and miscarriage risk, but researchers were cautious about drawing conclusions, and other studies found no such link. A more recent study indicated higher levels of physical activity were linked to a higher risk of very early pregnancy loss only in women with a history of miscarriage. However, for women with confirmed pregnancies, physical activity and miscarriage risk were unrelated. The consensus supports that exercise is safe and beneficial for most healthy pregnancies.
Guidelines for Safe Exercise
For most healthy people, at least 150 minutes of moderate-intensity aerobic activity each week is recommended during pregnancy. This can be broken into shorter sessions, such as 30 minutes daily or 10-minute intervals. Moderate intensity means you should be able to carry on a conversation while exercising, but not sing. Listening to your body and adjusting activity levels is key, as energy levels and physical capabilities change throughout pregnancy.
Staying well-hydrated with plenty of water before, during, and after exercise prevents overheating and dehydration. Wearing loose-fitting clothing and exercising in a temperature-controlled environment also helps manage body temperature. Avoid exercising outdoors during very hot or humid conditions.
Safe exercises during early pregnancy generally include:
Walking
Swimming
Stationary cycling
Modified yoga or Pilates
Low-impact aerobics
Activities to avoid include those with a high risk of falling or abdominal injury, such as:
Contact sports (e.g., basketball, soccer)
Downhill skiing
Horseback riding
Gymnastics
Scuba diving (due to decompression sickness risk for the baby)
After the first trimester, avoid exercises that involve lying flat on your back for extended periods, as this can compress major blood vessels.
When to Seek Medical Advice
Stop exercising immediately and contact a healthcare provider if you experience certain warning signs. These include vaginal bleeding or fluid leakage, which could suggest complications. Dizziness, lightheadedness, or feeling faint are also reasons to cease activity.
Other symptoms warranting immediate medical attention include:
Chest pain
Persistent headaches
Unusual shortness of breath not related to exertion
Calf pain or swelling, especially if in only one leg (could indicate a blood clot)
Painful uterine contractions
Abdominal cramping
Significant decrease in fetal movement