Bacteriology, antibiotic treatment effect and adverse birth outcomes in pregnant women with and without bacteriuria: a registry study.

PURPOSE: To investigate bacteriology, antibiotic treatment and adverse birth outcomes (ABOs) in pregnancies with and without bacteriuria and urinary tract infections (UTIs) based on urine cultures and clinical diagnoses.

METHODS

Registry-based cohort study.

POPULATION: Pregnancies with at least one urine culture analysed at one of two hospitals in the Capital Region, Denmark, between 2015 and 2021. Data were collected from clinical and national health registries. Descriptive statistics, t-tests, and logistic regressions were applied.

MAIN OUTCOME MEASURES: Odds of ABOs (low birth weight (LBW), small for gestational age (SGA), prematurity), and the impact of antibiotic treatment.

RESULTS

74,253 pregnancies in 62,439 women with 178,599 urine cultures were included; 3,498 (4.7%) with a positive urine culture, of whom 2,786 had bacteriuria (no UTI/ASB diagnosis), 533 with a UTI diagnosis, and 179 with an ASB diagnosis, and 70,755 pregnancies without a significantly positive urine culture (comparison group). Escherichia coli (9.3%) was the most common uropathogen. Of included pregnancies, 43% received antibiotic treatments, and the average treatment timing was empirical. Bacteriuria and UTIs in pregnancy increased the odds of ABOs, and antibiotic treatment was associated with reduced odds. ASB was not associated with ABOs.

CONCLUSION

Bacteriuria and UTIs in pregnancy, but not ASB, were significantly associated with ABOs and a lowering of odds of LBW when antibiotically treated. Our findings highlight the importance of pregnancy diagnostics, the consequences of bacteriuria, but also that further research on ASB is highly needed.