Moderate Intensity Exercise in Pregnant Patients with Cardiovascular Disease: A Pilot Study.

BACKGROUND: Exercise in pregnancy has proven health benefits, yet the safety of exercise in patients with pre-existing cardiovascular disease (CVD) has not been established. Our aim was to determine the feasibility and safety profile of moderate intensity exercise during pregnancy in patients with CVD, compared with those without CVD.

METHODS: This is a prospective single center pilot study of a moderate intensity exercise regimen, with data collection through wearable fitness trackers and personal exercise logs in pregnant patients with and without pre-existing CVD. The primary outcome was Doppler umbilical artery systolic to diastolic (S/D) ratio measured between 32-34 weeks' gestation. The secondary outcomes were adverse maternal and fetal events, trends in wearable fitness tracker data, C-reactive protein levels, and weight changes.

RESULTS: At baseline, the CVD group (62% congenital heart disease) took part in more pre-pregnancy walking, less weightlifting, and had a higher body mass index compared to the control group, and on average walked 539 fewer steps per day during pregnancy than the control group. Resting heart rate (HR) was found to increase in both groups up to 30 weeks' gestation. The cardiovascular disease group displayed an overall lower exercise intensity, as measured by the ability to increase HR with exercise over resting heart rate one hour prior to exercise at study baseline (45% vs. 59% P<0.001). Umbilical artery S/D ratio was normal in both groups. No differences were seen in adverse events between groups.

CONCLUSIONS: This pilot study of moderate intensity exercise in pregnant individuals with pre-existing CVD demonstrated that patients with CVD were not able to increase their HR during exercise throughout pregnancy compared to those in the control group. Although a small study group, this data supports the hypothesis that exercise interventions during pregnancy for patients with CVD are feasible without evidence abnormal fetal Doppler profiles. Further studies using wearable fitness trackers may provide the opportunity to understand how to safely tailor exercise programs to pregnant individuals with CVD.