This cross-sectional study examined mechanisms through which exercise might alter preeclampsia risk by estimating the effects of acute and chronic exercise on angiogenic markers in healthy pregnant women with different amounts of regular exercise participation. Serum-soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and soluble endoglin (sEng) were measured before and after 20 min of moderate-intensity cycle ergometry in normotensive, nonsmoking pregnant (16 active, 9 inactive, 34.1+/-1.6 wk gestation) and nonpregnant (15 active, 12 inactive, midlate luteal phase) women. Inactive women did not regularly exercise at an intensity that was sufficient to cause sweating. Active women exercised for at least 3 h/wk. Inactive pregnant women had significantly lower PlGF concentrations [median (interquartile range): 268 (159, 290) vs. 278 (221, 647) pg/ml, P=0.014] and higher sFlt-1 [5,180 (4,540, 5,834) vs. 4,217 (2,014, 5,481) pg/ml, P=0.005] and sEng concentrations [9.1 (7.7, 16.7) vs. 7.8 (6.5, 10.1) ng/ml, P=0.025] than active pregnant women. This effect of regular exercise participation was not observed in nonpregnant women. Acute exercise in pregnancy was not associated with antiangiogenic changes that might contribute to preeclampsia; rather, there was a small, but statistically significant, increase in PlGF following acute exercise in active pregnant women [278 (221, 647) vs. 335 (245, 628) pg/ml, P=0.014]. sFlt-1 increased significantly following acute exercise in inactive nonpregnant women [90 (86, 100) vs. 106 (101, 116) pg/ml, P=0.012], but not in active nonpregnant women. Regular exercise during pregnancy is associated with higher serum PlGF and lower sFlt-1 and sEng concentrations in late gestation, a difference that is unlikely to have predated the pregnancy.