Four studies were included in this review: three prospective cohort studies (n=1,156) and one case-control (n=316). One study explicitly addressed duration of the antibiotic intervention; the other three examined efficacy without specifically focusing on duration.
The quality assessment in terms of the study's ability to evaluate the impact of duration on the outcomes was judged to be poor for two studies and fair for two studies in terms of high-risk women. For low-risk women the quality of all four studies was deemed to be poor
Duration and neonatal GBS colonisation: in the three cohort studies, prophylaxis was associated with a reduced likelihood of colonisation compared with no prophylaxis, but the duration at which this occurred varied from 1 to 2 hours to >4 hours. The case-control study reported prophylaxis of 2 hours or more significantly reduced the likelihood of neonatal GBS sepsis, but prophylaxis of less than 2 hours had no effect. In all studies the majority of patients received no prophylaxis.
Duration and early-onset GBS disease of the newborn: data on this outcome were reported from four studies.