Can Running Cause a Miscarriage? Exploring the Risks and Benefits for Expecting Mothers

Discover the truth about running during pregnancy. Explore the potential risks of a miscarriage and benefits for expecting mothers to make informed decisions for a healthy journey.

Benjamin Bunting BA(Hons), PgCert., AAPTI.

11/29/20247 min read

Understanding Miscarriage

Miscarriage (clinically termed spontaneous abortion) refers to the early loss of a fetus prior to 20 weeks gestation, an event which unfortunately occurs in an estimated 10%-20% of known pregnancies.

Though exact figures vary greatly, miscarriage remains an integral aspect of reproductive health that impacts many families.

Its emotional and physical repercussions have far-reaching ramifications on women both physically and psychologically, negatively affecting both physical health and their psychological well-being.

Miscarriage risks can vary, including genetic abnormalities, hormonal imbalances, anatomical issues with the uterus and chronic health conditions such as diabetes or thyroid disorders.

Lifestyle factors like smoking, excessive alcohol consumption and severe obesity have also been shown to increase miscarriage risk.

Expecting mothers should be aware of all possible factors to make informed decisions regarding their health and activities during their pregnancies.

Miscarriage can have an enormous emotional toll, often leaving partners and family members reeling with grief, loss and guilt.

Exercise During Pregnancy: The Science Behind It

Understanding the physiological changes that take place during gestation is integral to understanding how exercise impacts maternal and fetal health.

Women experience hormonal fluctuations, increased blood volume, and changes in cardiovascular fitness during their pregnancies. These adaptations support growth and development while simultaneously preparing their bodies for childbirth.

Research consistently shows the many benefits of exercise during pregnancy. Physical activity has been linked with lower risks of gestational diabetes, hypertension, and excessive weight gain.

Exercise also alleviates common discomforts like back pain and fatigue during gestation. Experts recommend that pregnant mothers engage in moderate exercise, such as walking, swimming, or low-impact aerobics, for at least 150 minutes each week during their gestation period.

Risks Associated With Running While Pregnant

Running during pregnancy can be beneficial, yet it is essential to be mindful of its potential risks. One primary risk is injury: pregnant women experience physical changes that alter balance, joint stability and posture.

These factors increase the chance of falls or injuries, especially in the later stages of gestation. To minimise such risks, women who run are advised to choose safe environments and be wary of uneven surfaces.

Dehydration poses another significant risk during gestation. Ensuring that pregnant runners remain adequately hydrated is especially essential, since dehydration can increase body temperature and have adverse consequences for both mother and fetus.

Pregnant runners must drink ample fluids before, during, and post runs to remain well-hydrated and avoid dehydration as much as possible.

Overheating during pregnancy is also a serious risk, with elevated body temperatures having the potential to compromise fetal development in the first trimester.

Pregnant women should therefore avoid running during extreme heat; in such instances, they should look for cooler times of the day or indoor running options when temperatures increase.

A 2012 study found that those who would train at an intensity above 90% of their maximal heart rate could reduce the blood flow to the fetus and reduce their well-being.

Furthermore, certain medical conditions, including preterm labour history or high blood pressure, increase risks when it comes to running (for instance prior preterm labour or complications may make running riskier).

Women without contraindications should engage in regular pregnancy exercise while being monitored frequently during gestation. Warning signs for ceasing exercise could include:

  • Regular painful contractions lead to vaginal bleeding

  • Amniotic fluid leakage and dyspnoea prior to exertion have been reported

  • Dizziness/syncope, headache, chest pain, muscle weakness and calf pain or swelling.

Does Running Lead to an Earlier Delivery?

In this study published in the British Medical Journal, no significant differences were noted in gestational age at delivery or birthweight centile between women who discontinued running during gestation and those who continued running.

This was regardless of distance covered or gestational stage, suggesting that recreational running per se has limited effects on placental function or mechanisms that initiate labour onset.

Pressure or impact effects on cervical integrity from running during gestation do not influence when labour will commence, although continuing running during gestation increases your risk of assisted vaginal delivery, relative to those who stop running before gestation begins.

Overall, assisted vaginal delivery rates were relatively high (25%). Although most women reporting their first pregnancy reported assisted vaginal delivery as being part of their plan, overall this statistic may reflect that these primiparous women may have higher assisted vaginal delivery rates due to being primiparous women themselves.

One likely explanation for an increase in assistance among runners may lie within their pelvic floor muscles.

Exercise may provide soft tissue resistance against crowning of the fetal head during the second stage and result in delayed second-stage labour and therefore an increased need for assisted vaginal delivery assistance.

Overall, these findings and previous work can give pregnant women who wish to continue running during gestation the confidence that it will not negatively impact the birth weight of their baby or increase its likelihood of preterm delivery.

However, expecting mothers should listen to their bodies and prioritise safety when it comes to both their own health and that of their unborn child.

Running While Pregnant Can Have Multiple Benefits

Regular physical activity such as running can improve cardiovascular fitness, strengthen muscles and increase endurance.

Furthermore, running can assist expectant mothers in maintaining a healthy weight during gestation which is beneficial given potential complications associated with excessive weight gain during gestation.

Running not only has physical benefits but has been demonstrated to help boost mental well-being. Pregnant mothers frequently experience mood swings and anxiety due to hormonal shifts and anticipation of becoming parents.

Regular running can help soothe these emotional fluctuations by releasing endorphins (also referred to as 'feel-good hormones") which have the power to alleviate emotional instability by producing endorphins - biochemical responses known for relieving tension levels and improving emotional well-being.

Aerobic exercise such as running has been shown in studies to improve their sleep patterns. Pregnancy often disrupts sleeping patterns, but engaging in moderate-intensity workouts can contribute to better quality and duration of restful slumber.

Thus providing essential restful recovery to both physical and mental well-being during gestation.

Additionally, developing and sticking with a running routine during pregnancy is known to boost self-esteem and body image at a time when many women may feel insecure with their changing bodies, relieving anxiety and depression symptoms.

Furthermore, running provides a sense of routine during gestation, providing women with precious alone time during this transformative phase in their lives.

Expert Advice and Guidance for an Economic Future

Some medical professionals and health organisations have expressed serious concern over running during pregnancy and its potential risks.

According to the American College of Obstetricians and Gynecologists (ACOG), moderate physical activity during gestation is both safe and encouraged by doctors.

ACOG specifically notes how engaged exercise like running can bring numerous physiological advantages, including improved mood, improved sleep quality and decreased gestational diabetes or weight gain risks.

ACOG guidelines suggest that pregnant individuals should aim to engage in at least 150 minutes of moderate-intensity aerobic activity per week, such as walking, swimming or running based on individual fitness levels before pregnancy.

Running enthusiasts may continue their practice but should listen to their bodies and adjust routines as necessary; pregnant individuals with preexisting conditions or complications must consult healthcare providers prior to engaging in running or other forms of physical exercise.

ACOG recommendations emphasise the importance of being properly prepared before engaging in physical activity.

Always selecting suitable footwear, staying hydrated and avoiding overly strenuous environments or extreme temperatures are all ways that mothers-to-be can minimise risks related to running during gestation.

Furthermore, adjustments may need to be made as gestation progresses to accommodate changes in body mechanics and energy levels.

Insights of Athletes during Pregnancy

An increasing number of elite female athletes reach their peak performance and desire to continue competing during years with optimal fertility.

At the 2016 IOC expert group meeting in Lausanne, evidence reviewed and recommendations made were highlighted as showing an overall lack of high-quality evidence specific to pregnant elite athletes.

The lack of evidence is specifically around the impact of high-intensity training or extreme doses of exercise during gestation on maternal, newborn and return-to-competition outcomes, along with athlete recovery post-birth.

These recommendations and advice are grounded in scientific evidence when available, and derived by reaching consensus among 16 experts from diverse countries, healthcare systems, and disciplines.

Many female runners have engaged in running while pregnant, providing invaluable insights that demonstrate the relationship between physical activity and maternal health. Each athlete's journey varies depending on individual circumstances, the nature of their sport, and personal health considerations.

Here we look at a couple of studies that investigate the behaviours and outcomes of professional runners training during pregnancy.

This 2023 study published in the Medicine and Science in Sports and Exercise journal reported forty-two elite middle/long distance runners underwent data collection to examine their training before, during, and after pregnancy as well as competition data.

That data showed that running volume steadily declined during gestation and returned to prepregnancy training volumes by three months postpartum for most participants (6 weeks postpartum).

Participants aiming to return to equivalent performance levels during postpregnancy reported no significant decline in performance one to three years of postpregnancy compared with prepregnancy; instead 56% improved performances during postpregnancy.

A study published in 2015 looked at the habits of competitive runners during pregnancy. The study found that 70% of pregnant runners ran sometime during their gestation(s), yet only 31% ran during the third trimester.

On average, women reduced training during gestation to approximately half the intensity they used when running before gestation.

Only 3.9% reported running injuries while pregnant; just under one-third (29.9%) indicated maintaining fitness through running during gestation as their reason.

Women who breastfed reported running during breastfeeding. Most felt it had no negative impact on their ability to breastfeed.

Women who ran while breastfeeding were less likely to report postpartum depression compared with those who did not, although we did not observe an association between running during gestation and postpartum depression.

Does Exercise During Pregnancy Cause Miscarriage?

Light to moderate intensity leisure-time physical activity does not increase miscarriage risk; indeed it may even lower it.

One study revealed an increased risk of miscarriage after higher than usual physical strain on days 6-9 after the estimated date of ovulation.

A large epidemiological study revealed an increased risk of miscarriage among women engaging in high-impact exercise for over 7 hours a week during their first trimester, specifically.

However, there is currently insufficient data available to pregnant elite athletes about miscarriage risks when engaging in high-intensity, speed, endurance or weight training in their first trimester.

Conclusion: Making Informed Decisions

As pregnant mothers contemplate whether running can cause miscarriage, they must make an informed decision tailored to their circumstances.

While moderate exercise - including running - may provide significant advantages during gestation, its outcomes depend on each woman's unique medical history and her pregnancy itself.

So before beginning or continuing any running routine during this vulnerable time, it is essential that risks and benefits are carefully considered before making a commitment to engage in a running routine.

Consulting your NHS is key in the decision-making process. A doctor or qualified healthcare professional can offer customised recommendations based on an expectant mother's health status, fitness level before gestation and any existing complications that require modifications to your exercise routine.

Communicating openly with healthcare professionals helps clarify risks while leading them towards safe practices.

As well, it's essential to recognise the changing nature of pregnancy itself when planning physical fitness exercises during gestation.

Variations in energy levels, body mechanics and overall comfort may alter an expectant mother's ability to run, so listening to one's body and making appropriate modifications to exercise plans is key for having a satisfying pregnancy journey.

By striking a balance between staying active while protecting both mother and baby's health during this journey with greater ease and confidence.