- Acute pyelonephritis is one of the most frequent medical complications of pregnancy, as well as a common cause of antepartum hospitalization. Interferon (IFN)-gamma inducible protein, CXCL10/IP-10, is a member of the CXC chemokine family with pro-inflammatory and anti-angiogenic properties. The purpose of this study was to determine whether maternal serum concentrations of CXCL10/IP-10 change in patients with acute pyelonephritis during pregnancy. This cross-sectional study was conducted to determine the difference in maternal serum concentrations of CXCL10/IP-10 in pregnant women with acute pyelonephritis (N = 41) and normal pregnant women (N = 89). Pyelonephritis was defined in the presence of a positive urine culture, fever, and maternal clinical signs; blood cultures were performed in 36 cases. Maternal serum concentrations of CXCL10/IP-10 were measured by a sensitive immunoassay. Non-parametric statistics were used for analysis. (1) The median serum concentration of CXCL10/IP-10 in pregnant patients with pyelonephritis was significantly higher than in normal pregnant women (median 318.5 pg/mL, range 78.8-2459.2 vs. median 116.1 pg/mL, range 40.7-1314.3, respectively; p < 0.001); (2) maternal median serum concentrations of CXCL10/IP-10 did not differ significantly among patients with acute pyelonephritis with and without bacteremia (positive blood cultures: median 362.6 pg/mL, range 100.2-2459.2 vs. negative blood cultures: median 298.9 pg/mL, range 108.5-1148.7, respectively; p = 0.3). Pyelonephritis in pregnant women is associated with an increased maternal serum concentration of the chemokine CXCL10/IP-10.