Renal infection and pregnancy outcome.

To evaluate the impact of renal infection on pregnancy outcome, we studied a group of pregnant women with asymptomatic renal bacteriuria and another group who had acute pyelonephritis. In 248 women with asymptomatic bacteriuria, infection was localized by the antibody-coated bacteria method. These women were prospectively matched with abacteriuric control subjects and we found no adverse effects of treated renal or bladder infection. Specifically, the number of women with hypertension and anemia in each group was similar, and infants born to these women were comparable regarding perinatal mortality, mean gestational age, and birth weight, as well as indices of maturity. A total of 487 women with acute pyelonephritis were evaluated in a case-control study and observations of the correlation of maternal anemia and pyelonephritis were confirmed. Women with antepartum infection had no increased adverse perinatal outcome; however, in some women with intrapartum infection, pyelonephritis appeared to have initiated premature labor. We concluded that treated renal infection, whether symptomatic or asymptomatic, does not significantly modify pregnancy outcome.