Cord blood gas patterns identifying newborns at increased risk of group B streptococcal sepsis.

The effect of group B streptococcal sepsis acquired in utero on umbilical cord gas values is not known. Hypothesizing that fetal acid-base balance may be affected, we sought to identify a pattern of cord gas values that might detect newborns at increased risk of group B streptococcal sepsis. This review encompassed all newborns from January 1, 1986 to March 31, 1990 who manifested group B streptococcal sepsis as confirmed by a positive blood culture. An increased-risk cord gas profile was identified as an arterial pH less than 7.18 with either an arterial carbon dioxide pressure less than 59 mmHg or bicarbonate level less than 19 mEq/L. This pattern was found in four of 11 newborns with group B streptococcal disease but in only 43 of 4290 controls, yielding a relative risk of 51.7 (95% confidence interval 13.1-224.9). Our results suggest that a mild metabolic acidosis characterized by these indices may serve as an indicator of increased risk of early-onset group B streptococcal disease.