Vertical transmission of group B Streptococcus. Relation to intrauterine fetal monitoring.

A prospective study of 70 mother-infant pairs was designed to evaluate vertical transmission of group B Streptococcus (GBS) in relation to the use of intrauterine fetal monitors (IUFMs). Multiple-site cultures obtained from mothers during the intrapartum interval and those obtained from infants on day 1 and at discharge or day 4 were plated on a selective medium. Thirteen (27.1%) of 48 IUFM-exposed women vs seven (31.8%) of 22 non-IUFM-exposed women had GBS at one or more sites. The GBS colonization with maternally concordant serotypes occurred in eight (61.5%) of 13 infants born to GBS-colonized, IUFM-exposed women vs two (28.6%) of seven infants born to GBS-colonized, non-IUFM-exposed women. While this suggests that vertical transmission of GBS is enhanced by IUFM placement, the differences in these infant rates were not statistically significant.