The benefits of prenatal exercise are well-established, both for parent and child. A few of these benefits include fewer pregnancy aches and pains, shorter labors, fewer interventions during labor, and a quicker postpartum recovery.
Despite the overwhelming amount of evidence supporting its efficacy, exercise during the earlier stages of pregnancy — specifically during the first trimester — tends to cause uncertainty for those fearing a miscarriage. This can be especially true for those who may have experienced a prior pregnancy loss.
Let’s set the record straight so you can proceed with knowledge rather than fear. This article will point out how common miscarriage is, the known causes to date, and some evidence-based exercise guidelines that will help you navigate the uncertainty of the first trimester.
Miscarriage Fast facts
- Miscarriage is a form of pregnancy loss that occurs up to 20 weeks gestation (after 20 weeks, it is referred to as stillbirth).
- Miscarriage occurs in about 10-20% of known pregnancies (Wilcox et al., 1988).
- The primary cause of miscarriage is chromosomal abnormalities – with one study finding this to be the cause of 82% of first trimester miscarriages (Ozawa et al, 2019).
Think about that last point: About 8 in 10 miscarriages are due to factors outside of one’s control. Hopefully, this will help you to reframe any blame or guilt you may feel if you’ve already experienced early pregnancy loss, or allay fears that you could cause a future miscarriage.
Exercise is NOT a Causative Factor
Some factors have been found to potentially increase the risk of having a miscarriage, such as maternal age, obesity, and alcohol consumption (Mayo Clinic, 2021). However, at this time, exercise does not appear to cause a miscarriage (Davenport et. al., 2019).
Of course, because the specific cause of a miscarriage often goes undetermined, many people are quick to blame themselves for something they did, especially exercise. This can create a lot of hesitancy and fear around exercise. So, below are some guidelines to help you move your body in a safe way and minimize risk to the fetus.
Safe Exercise Guidelines
It’s important to start by recognizing the official guidelines put forth by the American College of Obstetricians and Gynecologists (ACOG). ACOG advises those with uncomplicated pregnancies to engage in aerobic and strength-training activities before, during, and after pregnancy — with a goal of at least 20-30 minutes per day of moderate intensity activity on most, if not all, days of the week.
Activities to Avoid
ACOG advises people to avoid the following activities:
- Contact activities with high risk of abdominal trauma
- Scuba Diving
- Exercise in High Heat and Humidity
Additional Tips for Safe & Effective Exercise
ACOG also provides the following tips to minimize risk to the fetus:
- Use RPE to gauge your intensity (not a heart rate monitor). To understand what RPE is and how to use it to find a safe and effective intensity during exercise, see this article on finding a safe intensity to work at. Those who were sedentary before pregnancy should begin at a lower intensity and follow a more gradual progression.
- Stay well hydrated and avoid high heat and humidity to protect against heat stress, particularly during the first trimester.
Tips to Get You Started
Here are a few resources that can help you exercise safely and effectively during pregnancy:
Warning Signs to Stop
ACOG lists the following as signs to stop exercise. You may wish to consult your medical provider as well:
- Vaginal bleeding
- Abdominal pain
- Regular painful contractions
- Amniotic fluid leakage
- Dyspnea before exertion
- Chest pain
- Muscle weakness affecting balance
- Calf pain or swelling
The Bottom Line
The important takeaway is that there is no evidence to date that says that exercise causes miscarriage (the primary cause is chromosomal abnormalities). Moreover, ACOG strongly urges regular physical activity for the benefit of the pregnant person and the fetus. Be sure to follow the guidelines above to ensure you are exercising in a way that minimizes stress to the fetus.
If you are interested in safe and effective total body workouts for all stages of pregnancy, check out our prenatal training programs and services. Or, if you are a health and fitness professional interested in learning how to coach pre & postnatal clients, explore our pre & postnatal professional education.
Davenport, M.H., Kathol, A.J., Mottola, M.F., et al. (2019). Prenatal exercise is not associated with fetal mortality: a systematic review and meta-analysis. British Journal of Sports Medicine. 53, 108-115.
Ozawa, N., Ogawa, K., Sasaki, A., Mitsui, M., Wada, S., & Sago, H. (2019). Maternal age, history of miscarriage, and embryonic/fetal size are associated with cytogenetic results of spontaneous early miscarriages. Journal of assisted reproduction and genetics. 36(4), 749–757.
Wilcox, A.J., Weinberg, C.R., O’Connor, J.F., Baird, D.D., Schlatterer, J.P., Canfield, R.E. (1988). Incidence of early loss of pregnancy. New England Journal of Medicine. 319, 89-94.