A study carried out 2 to 12 months after women discovered to have bacteriuria during pregnancy were delivered of their infants has shown the following: (1) bacteriuria persisted in 90 of 111 untreated women; (2) bacteria were present in urine obtained from one or both ureters in 17 of 23 patients; and (3) pyelographic abnormalities were detected in 61 of 131 patients. These findings suggest that in many instances asymptomatic bacteriuria first noted during pregnancy persists following delivery and is associated with active renal infection.
Whalley PJ, Martin FG, Peters PC. Significance of Asymptomatic Bacteriuria Detected During Pregnancy. JAMA. 1965;193(11):879-881. doi:10.1001/jama.1965.03090110017004