Risk factors for recurrence of group B streptococcus colonization in a subsequent pregnancy.

Objective: To document rates of recurrent group B streptococci (GBS) colonization in women with previous GBS colonization in an initial pregnancy and to assess maternal risk factors associated with recurrence.

Methods: A retrospective, longitudinal study was performed in a teaching hospital on women with GBS colonization who were pregnant between 2002 and 2006 and had at least one subsequent pregnancy during the same time period. When only the index and first subsequent pregnancy were analyzed, the cohort included 251 women. The rate of recurrence was estimated for GBS colonization in the pregnancy after the index pregnancy for GBS colonization. Multivariable regression models were constructed to model recurrence of GBS colonization in a subsequent pregnancy as functions of potential predictors to estimate relative risks and confidence intervals.

Results: The rate of recurrence of GBS colonization in the pregnancy subsequent to the index pregnancy was 38.2% (95% confidence interval 33.5-42.9%). Multivariable regression models showed that the time interval between the two pregnancies and the intensity of GBS colonization from the index pregnancy were predictive of recurrent GBS colonization.

Conclusion: More than one third of women had recurrent GBS colonization in a subsequent pregnancy. These findings should assist clinicians in counseling women with GBS colonization about their risk for recurrence, the importance of appropriate prenatal GBS screening in a subsequent pregnancy, and intrapartum antibiotic prophylaxis for unknown GBS status.