Pregnant Elite Athletes Face Training Dilemmas as Review Maps Exercise Risks and Benefits

Elite female athletes often reach the peak of their sporting careers at the same time they reach the peak of their fertility, and a new review argues that the generic exercise advice given to most pregnant women does not serve this group well. The review, published in Physiological Reports, synthesizes evidence on how pregnancy reshapes maternal physiology, how exercise alters those changes, and where high-level training may carry risks that ordinary pregnancy guidelines never address.

The authors conducted two independent literature searches in September 2025 using PubMed and medical subject headings including “pregnant athletes,” “female elite athlete,” “maternal health,” and “exercise pregnancy.” Studies were eligible if they contained primary data on athletes who were pregnant or had recently delivered, with non-pregnant women included as controls in some cases. Case reports and non-human studies were excluded. From 56 candidate studies, the review included 40 studies with clinical data on more than 4,163 women, among them elite athletes.

Pregnancy transforms nearly every maternal physiological system, and these changes directly constrain training. Metabolic demand rises, contributing to weight gain and an elevated resting heart rate, yet maximal heart rate capacity decreases as gestation progresses, shrinking the heart rate reserve available to adapt to exercise stress. After roughly 20 weeks of gestation, the enlarging uterus can press on the aorta and inferior vena cava, reducing venous return and potentially lowering cardiac output, a phenomenon known as supine hypotensive syndrome. Shifting posture also matters: as the center of gravity moves with uterine expansion and breast enlargement, gait biomechanics change, particularly after the first trimester. These anatomical shifts may require modifications in the type and intensity of physical activity across different stages of pregnancy.

For the general pregnant population, the evidence base is comparatively strong. The American College of Obstetricians and Gynecologists recommends moderate exercise, such as aerobic and strengthening activities, throughout pregnancy in the absence of medical contraindications. According to the review, non-high-intensity exercise is associated with improved cardiorespiratory fitness and reduced risks of gestational diabetes mellitus, hypertensive disorders, excessive gestational weight gain, lumbopelvic pain, urinary incontinence, and fetal macrosomia. Lowering the likelihood of obesity and gestational diabetes in turn reduces the risk of preterm birth. Exercise has also been shown to reduce anxiety and prenatal depression, and moderate, safe exercise does not increase the risk of adverse outcomes; the risk of low birth weight and small gestational age is unrelated to exercise. Greater benefits have been observed with higher frequency and moderate intensity, often achieved in supervised classes because structured routines improve adherence.

Specific mechanisms appear to underlie some of these effects. Exercise interventions lasting 12 to 24 weeks improve cardiorespiratory fitness, which otherwise declines through pregnancy, while countering the risks of sedentary behavior, including thromboembolism and bone demineralization. Greater exercise volume and duration lower gestational weight gain, which often persists postpartum and raises long-term cardiovascular risk. Exercise reduces maternal and fetal leptin levels, hormones that contribute to fetal adiposity and are elevated in early pregnancy among women who gain excessive weight, and it reduces the likelihood of delivering a large-for-gestational-age infant. Maternal exercise has also been linked to improved fetal vascular function, with greater blood flow through the thoracic aorta and better endothelial function, and regular exercise can modestly increase the likelihood of a normal delivery. Cytokines released during exercise may reduce the risk of hypertensive disorders, and aerobic exercise combined with pelvic floor muscle training can help prevent stress urinary incontinence, a condition that persists postpartum in up to one-third of women with uncomplicated pregnancies.

The picture changes when intensity climbs to athletic levels. The review reports that exercising above 90 percent of maximal heart rate can lead to diminished fetal heart rate, a high uterine artery pulsatility index, and mean uterine artery blood flow falling below half of its initial volume, changes that can result in fetal growth retardation. The authors stress that this 90 percent threshold still needs further study to clarify its clinical significance, and they note that research is needed on acute fetal bradycardia and elevated umbilical artery pulsatility at high intensities. High-altitude training such as skiing or mountain biking carries a hypoxia risk that could compromise fetal oxygenation, and scuba diving and collision sports are among the activities pregnant athletes should avoid.

Not every demanding discipline is discouraged. Endurance training is described as among the most suitable forms for pregnant athletes, since moderate-to-high levels of exercise can maintain and even improve aerobic fitness, and endurance training has not been shown to harm pregnancy or delivery in athletes. Retrospective studies indicate that elite training levels are not necessarily associated with more complicated pregnancies, including higher rates of emergency cesarean section, prolonged second stage of labor, or severe perineal tears. Strength training is more contested: the Valsalva maneuver during intense weight training can decrease fetal blood flow, though this concern rests largely on expert opinion, and recent studies suggest high-intensity strength training is well tolerated by mother and fetus. Increased intra-abdominal pressure from heavy lifting can lead to incontinence or pelvic organ prolapse, but this is expected in non-pregnant women as well. Notably, athletes engaging in strenuous training show rates of low back pain, pelvic girdle pain, and urinary incontinence during pregnancy similar to non-athletes, and light-to-moderate strength training shows no adverse effects while producing strength gains. Some data even suggest heavy weightlifting during pregnancy is associated with lower rates of perinatal depression and cesarean section, and that women who maintained pre-pregnancy strength training levels had fewer reproductive and delivery complications, though support for Olympic weightlifting and supine lifting remains preliminary.

What happens after delivery is another open question, and one with career consequences. Because there is no definitive evidence on how pregnancy affects athletic performance, the review cites a study of 30 endurance athletes in which 11 percent achieved improved performance after pregnancy, 61 percent returned to the same level, and 28 percent did not. Breastfeeding, hormonal changes, and chronic fatigue can hinder the return to previous athletic potential, and returning to training too soon may raise injury risk because joint laxity remains elevated from pregnancy-related hormonal adaptations. Postpartum bodily changes have been linked to greater body dissatisfaction and drive for thinness among athletes than non-athletes, and these pressures, along with the possible end of an athletic career, fuel anxiety, frustration, and depression that are themselves associated with poor birth outcomes. Postpartum stress fractures also appear to increase, possibly from sudden increases in training load, prompting recommendations for adequate energy intake and calcium and vitamin D, particularly for athletes with a history of relative energy deficiency in sport or eating disorders.

The review’s authors are candid about the limits of the evidence. Fewer than a thousand elite-level athletes have been surveyed across the existing human studies, and the mechanisms by which exercise influences maternal weight gain and the likelihood of normal delivery remain undefined. Data are lacking on conditions more prevalent in athletes, such as relative energy deficiency in sport, whose long-term implications are unknown, and studies of eating disorders in pregnant athletes lack representative samples. Safe thresholds for strength training relative to aerobic capacity have not been established, and questions about supine exercise, high-altitude training, repeated Valsalva use, and long-term neurological outcomes in children repeatedly exposed to high-intensity exercise in utero remain unstudied. The authors call for randomized controlled trials and observational studies with sufficient power in female athlete populations, and for translating results into guidance for coaches, clinicians, and athletes.

Policy gaps compound the scientific ones. The review notes that professionals working with athletes, including sports medicine physicians and coaches, often lack knowledge about the physiology of pregnant athletes, which can delay returns to competition and even prompt sponsorship withdrawal, since paid leave during or after pregnancy is uncommon for elite female athletes. Qualitative studies show athletes hesitate to disclose pregnancies to coaches and organizations for fear of career damage, and a high rate of athletes end elite careers to focus on their children. The authors argue that sports organizations should allow more return-to-play time after childbirth, account for postpartum physical and mental changes in training plans, support breastfeeding, provide financial support, and adopt anti-discrimination policies, while advocacy should push for greater representation of women in the scientific literature. Until such evidence and policies mature, the review concludes that exercise regimens for pregnant athletes must be individualized, with input from sports medicine and obstetrics professionals, to protect both maternal and fetal health and the careers built on them.

Subject of Research: Exercise physiology, risks, and benefits of training during pregnancy in elite female athletes

Article Title: Exercise in pregnant elite athletes: Physiological considerations, risks, and benefits

Article References: Madera, I., Bhargava, V., Patel, J., Singh, K., Jawale, O., & Bachmann, G. (2026). Exercise in pregnant elite athletes: Physiological considerations, risks, and benefits. Physiological Reports, 14(20), Article e71148. https://doi.org/10.14814/phy2.71148

Image Credits: AI Generated

DOI: 10.14814/phy2.71148

Keywords: pregnancy, elite athletes, exercise physiology, fetal health, gestational diabetes, strength training, endurance training, heart rate threshold, postpartum recovery, sports policy, RED-S, maternal health