Additional antibiotic use and preterm birth among bacteriuric and nonbacteriuric pregnant women

Objective: To determine the risk of preterm birth related to use of additional antibiotics.Methods: Women with Group B streptococcal (GBS) bacteriuria and women with negative urine cultures in a hospital-wide research registry were included. The impact of prenatal antibiotics in addition to those used to treat GBS bacteriuria was assessed. Logistic regression was used to determine the risk of preterm birth among bacteriuric women who received “other antibiotics”.Results: A total of 203 women with GBS bacteriuria and 220 women with negative cultures were included. The frequency of preterm birth was 16% (35/220) for women in the control group, 16% (19/120) for women with bacteriuria not receiving additional antibiotics, and 28% (23/83) for women with bacteriuria who received antibiotics for “other indications”. Among women with GBS bacteriuria, the risk of preterm birth was increased with the use of “other antibiotics” (adjusted odds ratio, 2.7; 95% confidence interval, 1.2–6.1).Conclusion: Among women with GBS bacteriuria, exposure to additional antibiotics is associated with an increased risk of preterm birth.