Maternal and fetal cardiovascular responses to strenuous bicycle exercise.

In a longitudinal study we investigated some cardiovascular responses to strenuous bicycle exercise in 33 healthy women during pregnancy and the postpartum period. The exercise electrocardiogram demonstrated depression of the ST segment in 12% of women in the absence of clinical signs of ischemia, and the incidence of these changes was unaffected by pregnancy. In spite of slightly different blood pressures at rest during the first and second trimesters of pregnancy, the blood pressure response to exercise at approximately 75% Vo2max was virtually unaffected by pregnancy. After a maximal bicycle test, the fetal heart rate was increased by an average of 4 beats/min, without a change in pattern. Tocodynamometry suggested a transient increase in uterine activity after maximal exercise in 6% of the tests. These findings support the view that strenuous exercise of limited duration is not harmful to the healthy mother and fetus.