Gestational Changes in Exercise Capacity in Uncomplicated Singleton Pregnancies

BACKGROUND: Pregnancy is associated with well-characterized changes to the cardiopulmonary systems, yet few studies have quantified exercise capacity across trimesters in healthy pregnancies. OBJECTIVES: This study aimed to prospectively assess exercise capacity throughout pregnancy via cardiopulmonary exercise testing (CPET). METHODS: Healthy pregnant volunteers underwent ramp-protocol cycle-ergometer CPET in the 1st and 3rd trimesters. Volunteers were followed through delivery to record delivery mode, gestational age at delivery, fetal birth weight, and pregnancy complications. The mean CPET measures were summarized and compared between the 1st and 3rd trimesters with paired t-tests. RESULTS: pulse (11.0 vs 11.7 mL/beat, P = 0.39), and mean ventilatory efficiency (minute ventilation/volume of carbon dioxide produced and exhaled by the body per minute slope 31 vs 33, P = 0.28). The mean resting and peak heart rate increased significantly (P < 0.01), whereas the mean maximal voluntary ventilation (105 vs 98, P = 0.004) and hemoglobin concentration (13.0 vs 11.8, P < 0.01) decreased. No complications occurred during the CPETs or during labor and delivery. CONCLUSIONS: Despite the expected changes in hemoglobin and lung capacity, exercise capacity remained unchanged between the 1st and 3rd trimesters of pregnancy in healthy volunteers.