Effects of pregnancy and exercise on concentrations of the metabolic markers tumor necrosis factor α and leptin,

Objective: Pregnancy and exercise have opposite effects on fat mass and insulin resistance. We therefore designed this study to test the hypotheses that exercise during pregnancy alters the pregnancy- associated increases in the levels of tumor necrosis factor α and leptin and that the changes in tumor necrosis factor α and leptin concentrations during pregnancy continue to reflect changes in fat mass. Study Design: The levels of tumor necrosis factor α and leptin were measured longitudinally in a control group of physically active women, a group of women who performed endurance exercises ≥4 times a week throughout pregnancy, and a group of women who initially performed endurance exercises but then stopped exercising during midpregnancy. Exercise was monitored, and longitudinal estimates of maternal total mass and fat mass were obtained. Results: Tumor necrosis factor α levels were lower during pregnancy in the women who exercised, and the same was true for leptin levels. When women stopped exercising, however, both tumor necrosis factor α and leptin concentrations rose at rates comparable to those seen in the physically active control group. Changes in leptin concentration but not those in tumor necrosis factor α concentration correlated with the pregnancy-associated increases in total body and fat mass. Conclusions: Regular weight-bearing exercise during pregnancy suppresses the pregnancy-associated changes normally seen in both tumor necrosis factor α and leptin. The decrease in leptin reflects decreased fat accretion, and we speculate that the changes in tumor necrosis factor α may reflect a change in insulin resistance. (Am J Obstet Gynecol 2000;182:300-6.)