Exercise responses in pregnant sheep: blood gases, temperatures, and fetal cardiovascular system

Publisher Website
Google Scholar
Abstract
To examine of maternal exercise on the fetus, maternal and fetal temperatures and blood gases were measured and uterine O2 consumption was calculated in response to 3 different treadmill exercise regimens in 12 chronically catheterized near-term sheep. Fetal catecholamine concentrations, heart rate, blood pressure, cardiac output, blood flow distribution, blood volume and placental diffusing capacity were also measured. Maternal and fetal temperatures increased a mean maximum of 1.5 .+-. 0.5 (SE) and 1.3 .+-. 0.1.degree. C, respectively. Maternal and fetal blood gas values were corrected for the temperatures in vivo. Maternal arterial partial pressure of O2 (PO2), near exhaustion during prolonged (40 min) exercise at 70% maximal O2 consumption, increased 13% to a maximum of 116.7 .+-. 4.0 Torr; PCO2 decreased by 28% to 27.6 .+-. 2.2 torr. Fetal arterial PO2 decreased 11% to a minimum of 23.2 .+-. 1.6 Torr, O2 content by 26% to 4.3 .+-. 0.6 ml .cntdot. dl-1, PCO2 by 8% to 49.6 .+-. 3.2 torr, but pH did not change significantly. Recovery was virtually complete within 20 min. During exercise total uterine O2 consumption was maintained despite the reduction in uterine blood flow because of hemoconcentration and increased O2 extraction. The decrease of 3 Torr in fetal arterial PO2 and 1.5 ml .cntdot. dl-1 in O2 content did not result in major cardiovascular changes or catecholamine release. Maternal exercise does not represent a major stressful or hypoxic event to the fetus.