Key result
Pregnancy progression from first to third trimester does not alter exercise capacity in healthy volunteers.
Why the study?
Although pregnancy involves cardiopulmonary changes, few studies have quantified exercise capacity across trimesters in healthy pregnancies.
Does exercise capacity change between the 1st and 3rd trimesters in healthy uncomplicated singleton pregnancies?
Cohort
Does exercise capacity change between the 1st and 3rd trimesters in healthy uncomplicated singleton pregnancies?
Absolute Event Rate: 11.7% vs 11%
p-value: p=0.39
In healthy pregnancies, exercise capacity measured by CPET remains stable from the 1st to 3rd trimester despite expected physiological changes in hemoglobin and lung capacity.
Supports counseling on stable exercise tolerance in healthy pregnancies; leaves open mechanisms and generalizability to complicated cases.
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.
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Dwyer et al. (2026) conducted a cohort in Uncomplicated singleton pregnancies. 3rd trimester vs. 1st trimester was evaluated on Pulse (mL/beat) (p=0.39). Pregnancy progression from the 1st to 3rd trimester did not significantly alter exercise capacity, including pulse (11.0 vs 11.7 mL/beat, P=0.39), in healthy volunteers.
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